Locked Breech and Slide Delay

[1911Tuner]

I'm gonna open this one with a couple flat statements and a couple questions...and then I'm goin' to bed to let ya'll stew on it, 'cause I'm old and it's been a long time since 0400. So shoot me...

(Hill...I ain't the pup you might think. Hint: My profile skinny ain't exactly accurate...if ya get my drift.) ;)

We've all come to understand that the 1911 and other similar designs achieve the locked breech via the locking lugs...and the lock actually occurs under pressure, when the gun fires. Or...at least we should know by now.

The barrel engages with the slide vertically...but it locks horizontally...when the gun fires. This can be confirmed by looking at the original patents, as dictated to the legal eagles by none other than John Moses Browning himself.

But...How many really understand that there's very little difference between the 1911's Locked breech/Recoil Operation and the straight blowback pistol?
And that the only real difference lies in the method used to delay the breech opening.

Both designs operate by the same mechanics...by the same forces. Both are recoil operated...and both are blowback. This study will show how much the two overlap in function.

The 1911 is almost...ALMOST...a true delayed blowback. The one minor feature that keeps it from being so is the fact that...in the blowback...the slide cycles independently of the fixed barrel, and in the 1911...the barrel is a connected part of the slide temporarily, during the short recoil part of the operation.

This short recoil phase lasts for nominally 1/10th of an inch of slide travel during which the barrel is dragged backward by the slide. What that means in elapsed time...I an't got a clue. It ain't long, though.

Now...for the 64-dollar question:

How many understand the bullet's influence in delaying the opening of the breech?

There's a clew contained in all the stuff that came somewhere in the above writings.

Beddy-bye time!

Good night Chesty...wherever you are!

[Hawkmoon]

I will venture to hypothesize that the answer lies in the realm of "opposing force vectors."

Let's look at what happens when the powder ignites. It burns ... rapidly. This creates a pressure spike. The pressure is exerted equally in all directions but, because in all but two axes it is restrained by the chamber surrounding the cartridge, the pressure is free to act in only two directions: forward, and back.

In the forward direction, it gives the bullet a shove and sends it down the barrel. In the back direction, it gives the slide a shove and starts the slide (and barrel, as they are locked together at this stage) moving backward.

In a free system, these two opposing movements would occur independently. HOWEVER ... they cannot be 100 percent independent because the nature of a rifled firearm requires that the bullet engage the rifling in the barrel. This creates friction. In other words, at the same time the slide is trying to haul the barrel backwards with it, the bullet is trying to haul the barrel forward. This will tend to slow down (or delay) the unlocking of the barrel from the slide incrementally. It does not, howver, produce enough force to prevent the slide from even beginning to move before the bullet has departed the barrel.

How did I do, Professor?

[log man]

Okay, I propose an analogy as that can help understand a problem by simplifying the elements of the problem. :D

Therefore I believe a grand tug of war be waged between the well equipped Mr. Breech and the braggart Mr. Bullet. To begin the contest the two will hold on too a rope with a knot on one end, which Mr. Breech gets to hold and the other unknotted end to be held by Mr. Bullet, with about 4”of loose rope. At the signal they both begin to pull with amazingly equal force. Mr. Breech is smiling as he has a good hold on the knot while Mr. Bullet begins too feel the rope slip in his hands, as the rope slips little by little Mr. Breech holds fast, but due too the slippage he leans back a bit (about .100”too be exact) at which time Mr. Bullet lets go completely as the rope slips thru his hands and falls back rapidly as does Mr. Breech due too the lack of support that Mr. Bullet had provided until his departure. Recoil. :)

LOG

[Hawkmoon]

I think it's just great that we folks here are so highly educated that we can always express concepts of natural law in such highly technical and scientific terms.

It's wonderful, is what it is ... truly wonderful. :appld:

[John]

Ah hemmm, Mr. Breach??

You two guys can be the technical gurus of this site but one of you is not going to get top grades for spelling.

:lm:

[1911Tuner]

I will venture to hypothesize that the answer lies in the realm of "opposing force vectors."

That's probably the simplest, most direct term that I've seen to date.

"Opposing" being the catchword. As in...Each component striving to have its own way.

Kudos, Hawk! Outstanding!

[1911Tuner]

Breach holds fast, but due too the slippage he leans back a bit (about .100”too be exact) at which time Mr. Bullet lets go completely as the rope slips thru his hands and falls back rapidly as does Mr. Breach due too the lack of support that Mr. Bullet had provided until his departure. Recoil.

That's awful close, log...with only one point of contention. That being:


Mr. Bullet lets go completely as the rope slips thru his hands

Don't know if what you meant was that the bullet let completely go while it was still in the bore, or after it left.

It can't "let go" while it's in the bore. As long as it's there, and moving...its frictional contact with the barrel remains. Since the coefficient of friction doesn't change, no matter how fast its moving...the magnitude of resistance between bullet and barrel are constant.

The chink is that...as it moves faster, it requires less force to keep it moving...and less force to accelerate it to higher velocity that it took to get it started into the rifling to begin with. This is the part where many people get lost.

[John]

Kudos, Hawk! Outstanding!

Why do you think I keep him locked in his basement 8 hours every day?? He is trying to become Tuner, in Tuner's place. The next level will be to become John Moses in John Moses place!!!! LoRL :D :) :p

[1911Tuner]

Keep him on a short leash, John! I hear from reliable sources that he bites...

[Greyswindir]

The barrel and the slide are locked together for a brief moment, caused by pressure, of course. As others have already stated, the barrel is being "dragged or pushed" forward by the bullet and the slide is being propelled backward by the recoil/pressure of the ignited cartridge, which in turn locks the barrel solidly to the slide. Newtonian physics...opposite reactions occurring, etc.

So the delay is caused by the bullets forward thrust on the barrel which causes the slide and barrel lugs to lock... horizontally, like Tuner explained, keeping the breech tightly locked.

Once the bullet leaves the muzzle the pressure drops to zero proportionally (it doesn't drop to zero instantly...it happens gradually...but very fast by our human perspective, which is limited by the design of the eye! ) and the barrel starts to link down because of the loss of pressure...the slide continues its rearward momentum at the same time and the breech begins to open.

Was that somewhat correct? :o

[John]

...and the barrel starts to link down because of the loss of pressure...

Not exactly. The barrel links down because the link is pulling it down. What is important is that the pressure inside the barrel has subsided when the link pulls the barrel down and unlocks it from the slide.

[1911Tuner]

Was that somewhat correct?


Almost completely correct! Very good, young grasshopper...but you didn't quite finish.

WHY...does the bullet's influence delay the slide's rearward acceleration?

[kel]

The bullet is pulling the barrel forward as it is swaged into the lands and grooves? You have mentioned that point a couple of times before. This somewhat helps to offset the pressure of the case against the breechface that is pushing the slide backwards. It influences th slides rearward acceleration because the when the barrel pulls forward it takes the slide with it as much as the slide takes the barrel backwards.

[1911Tuner]

The bullet is pulling the barrel forward as it is swaged into the lands and grooves?

Correct.

This somewhat helps to offset the pressure of the case against the breechface that is pushing the slide backwards.

mmmmm...dunno if "offset" is the right descriptive term.

It influences th slides rearward acceleration because the when the barrel pulls forward it takes the slide with it as much as the slide takes the barrel backwards.

That's closer.

In a nutshell...

Because the barrel and bullet are under powerful frictional forces...each one imposing a like measure of force on the other...and because equal and opposite works in both directions, pushing or pulling...

Whatever resistance that the barrel offers to the bullet, the bullet also offers to the barrel. Since the barrel is moving rearward while the bullet is moving forward...albeit for only a fractional brief instant...As the barrel resists the bullet's movement, the bullet resists the barrel's movement...and since the slide is pulling the barrel backward...whatever resists the barrel resists the slide.

This is easily demonstrated...either in actual practice, or hypothetically.

Attach a cork to a rope and push it into a length of pipe that's sized to make the cork a tight fit. Pull on the rope with one hand, and the pipe with the other...gradually increasing the force until the cork slips. The instant that the cork slips in one direction, the pipe slips in the other.

As you continue to pull and keep the pipe and cork moving...you feel resistance in both arms. The cork is pulling on the pipe and the pipe is pulling on the cork...in opposing directions. Each one is offering resistance to the other, and any length of the pipe between the two is suffering a tensile stress...stretching.

This tensile stress is what cracks slides and stretches revolver topstraps, leading to excessive endshake...and as it grows...to increasing headspace. Study the picture below, and visualize the stress imposed on the slide in the area between the first lug wall and the breechface. Then, imagine the hard, sudden "punch" of the recoil impetus.

Illustration courtesy of Dana Kamm

http://i40.photobucket.com/albums/e243/1911Tuner/StressCracks.jpg

[log man]

That's awful close, log...with only one point of contention. That being:Don't know if what you meant was that the bullet let completely go while it was still in the bore, or after it left.


After it left of course, do you think Mr. Bullet is a quitter? No! After he grabbed the rope there was 4" left and he held on right to the end. :appld:

LOG

[1911Tuner]

After it left of course, do you think Mr. Bullet is a quitter? No!

Thaaaaaat's right. As long as the bullet is in the bore and moving...it offers resistance to the slide. Of course, it's all over in a couple nanoseconds...but its influence remains as long as it remains.

It may be worth mentioning that Kuhnhausen understood this...and that may be partly where he came up with the balanced thrust theory. He was thinking that the pull resistance held the slide in place until the bullet exited...and the sudden release of mutual resistance allowed the slide to start moving...like two kids pullin' on a rope in a tug of war, with no one clearly the stronger...and then one suddenly lets go. I believe that's what he was thinking...

[Jerry Keefer]

As long as the bullet is in the bore and moving...it offers resistance to the slide. Of course, it's all over in a couple nanoseconds...but its influence remains.

Hmmmmmm...So, yesterdays thread that vehemently blasted and mocked the concept of trying to utilize, and influence bore time, had some merit after all... resistance is resistance, whether it is in the form of weight , sprung pressure, or opposing bullet forces... Months ago I mentioned another engineer, an aero space guy who was on the ground floor of "smart bomb" developement, and noted national ballistic expert, who writes that there are things that happen during the internal ballistic event, that are unknown and cannot be measured, or proven with out a doubt....many things are speculative, which does not necessarily mean they don't happen. Does that automatically negate innovative efforts to strive for an effect..?
Even the most novice shooter can feel the difference imparted by the small radius stop. So, there must be an altered event from the norm... " Time ", is the ultimate measure of the universe. It waits not for man nor thing.. gun powder conversion to gas is not instant and can be mearsured in time. Each powder reacts differently, and produces different pressure peaks at different times, which effects bullet release, engraving pressure, acceleration times, and accuracy.
Internal ballistic events are a study unto them selves. If the slide is resisted and moves slower, "time" is altered relative to the "complete event"..


Jerry

[log man]

If the slide is resisted and moves slower, "time" is altered relative to the "complete event"..
Jerry

Interesting statement Jerry, however I can't believe that "time" is altered. The slide, barrel, bullet, case, powder, and primer are all part of the same event.

LOG

[kcshooter]

Wow, I can't believe that question was so fully and completely answered before I even showed up.

This forum has to be filled with the smartest and sharpest members of any I've seen. Solidly impressed.

[Hawkmoon]

Wow, I can't believe that question was so fully and completely answered before I even showed up.

This forum has to be filled with the smartest and sharpest members of any I've seen. Solidly impressed.
Tuner keeps us ... tuned. ;)

[1911Tuner]

So, yesterdays thread that vehemently blasted and mocked the concept of trying to utilize, and influence bore time, had some merit after all...

No no! The thread yesterday was to show that the balanced thrust vector theory is incorrect. Balanced force and motion can't coexist within a closed system. The result of balanced force is equilibrium...not motion. If something is in motion, the forces are unbalanced.

Delay isn't taken to mean stopped. Delay in this case means slowed. Nothing stops once it's started, until the forces are brought back into balance by the application of an outside force of sufficient magnitude to equal or overcome the momentum of the object in motion. A brick wall will do that. Friction in the bore, or a recoil spring won't...assuming that the compelling force is sufficient. Squib loads will allow the bore friction to stop the bullet...but that doesn't always stop the slide.

Just like the small radius stop delays the slide...it doesn't keep it from moving. it just causes it to accelerate more slowly. The same goes for the bullet's influence.

Ever seen a squib stick a bullet part-way down the bore...but the slide completes its cycle and chambers another round? I have.

I believe that Kuhnhausen assumed that the delay resistance offered by the bullet prevents the slide from moving until the bullet is gone...and that he got this from the understanding that the bullet does, in fact, offer resistance. What he didn't understand...or maybe just didn't articulate clearly...was that there is motion in both directions in spite of the opposing frictional forces.


many things are speculative, which does not necessarily mean they don't happen.

Agreed...but Newton's dictum of equal and opposite action/reaction isn't one that's open to debate. If there's an action, there must be a reaction...and that reaction is without delay. If the forces involved are sufficient to set both sides of the equation into motion...both will move, and they'll both start at the same instant. One side may move slowly, and only for a short distance...but move it must, even if the eye can't detect it. It doesn't have a choice.

Internal ballistic events are a study unto them selves. If the slide is resisted and moves slower, "time" is altered relative to the "complete event"..

No argument there...on any of the above points. But altered time doesn't mean that the objects in an action/reaction event will start...then stop...then start again. It also doesn't mean that one will wait for the other to finish what it started...and then begin its own journey.

To sum it up...Kuhnhausen's description states that the slide doesn't move until the bullet is gone. That means that the action side of the action/reaction pair is missing.
If it goes missing before the reaction starts, it may as well have never been there...because if there's no action...there's no reaction.

All that's left is the residual powder gasses and particulate to impose force on the slide. In the case of the .45 ACP cartridge...that works out to 5 grains of mass at roughly the speed of sound. Or about 1/6th the impetus generated by a .22 Short fired in an aluminum J-frame Smith & Wesson revolver.

[log man]

:confused: Tuner I didn't say that, that's Jerry's quote, how did you do that? You clever devil you. :confused:

LOG

Good man, Tuner.

[1911Tuner]

Ain't got a clue how that happened, log. I fixed it, though...

[Iron bottom]

So, I'd bet on a full metal jacket tugging a little harder on the barrel and slowing the slide a little more than lead. Correct? Also, does the path, spin and mass of the bullet as it passes through the barrel contribute much in the way of diminishing the upward rise of a pistol in recoil?

[saltydog]

Admittedly, I can be thick headed.

If pressure is exerted on the base of the brass and trasfered to the face of the breech, how does a stationary bullet prevent the slide from moving?

I've read the words, but can't seem to get my head wraped around all that pressure doing nothing to move the slide rearward. :confused:

salty

[1911Tuner]

So, I'd bet on a full metal jacket tugging a little harder on the barrel and slowing the slide a little more than lead.

Tough call on that one, Gerald, but I'd have to say...a little. A lead bullet isn't as resistant as a jacketed bullet. That's a given...but because the jacketed bullet is tougher, it causes a faster pressure spike and higher pressures. Higher pressures mean higher forces....so one may work to cancel the other out to some degree.

Because lead is less resistant...and because a given powder charge will produce lower peak pressures than a jacketed bullet of identical mass...all else being equal...the lead bullet will be less stressful on the whole assembly. Another point on lead bullets is that they also produce higher velocities at lower pressures than same mass jacketed bullets...so something is going on.

Also, does the path, spin and mass of the bullet as it passes through the barrel contribute much in the way of diminishing the upward rise of a pistol in recoil?

Everything means something...so it would have to have some effect. In the autopistol, it won't make as much difference as it would in a fixed-breech weapon like a revolver. Muzzle flip comes mostly from the slide striking the impact abutment in the frame. By the time that happens, the bullet is long gone.

Rotational torque still applies in full force, though...and I'd be willing to bet that the lowered coefficient of friction of the lead bullet would produce a measureable, "feelable" difference on that.

[1911Tuner]

If pressure is exerted on the base of the brass and trasfered to the face of the breech, how does a stationary bullet prevent the slide from moving?


Because until something moves, nothing happens. There can be 30 million pounds per square inch of pressure...but if nothing moves, the gun will just sit there and do nothing. No action...no reaction.

Let's take a hypothetical cannon made from an open tube. Let's assume that the ID of that barrel is perfectly round and concentric from one end to the other, with zero variation.

Let's assume two canon balls that are of identical mass and weight...perfectly round and smooth, also with no difference in their diameters. Perfect identical twins.

Let's place a powder charge in the geographic center of the cannon barrel, and load each ball to precisely the same distance from their respective muzzles.

When the cannon fires, both will accelerate at identical rates, and will exit their muzzles at precisely the same instant at precisely the same speed...and the cannon barrel won't recoil in either direction.

Now, go back and make one ball hollow, so that it's mass/weight is 1/10th that of the solid ball. All else is equal.

When we light the charge this time, the lighter ball will exit first. It will accelerate 10 times faster, and it will exit at 10 times the speed of the solid one...and the gun will recoil in the direction of the slower, solid ball. All this difference in spite of the fact that the force exerted on both balls was equal.

Why did the gun recoil in the slower ball's direction of travel? Because it was in the barrel and exerting a drag on the barrel as it moved after the lighter, faster ball had left.

In the first firing, each ball was both breechblock and projectile, and each one acted as a breechblock for the other.

In the second, the heavier ball was a moving breechblock for the lighter one. The slide on a 1911 pistol is nothing more than a moving breechblock.

In either instance, had both balls been mechanically blocked and unable to move...nothing would have happened unless the charge was powerful enough to burst the barrel. The "gun" would have sat there and gone pffft as the pressure leaked down unless it was perfectly sealed.

I won't warp your head any further by tellin' ya that...in the first firing...the balls would have had equal but opposite velocities.

Whoops! I just did! :D

[saltydog]

Thanks.

If there were just one ball and it was spiked in a stationary position so as not to move, there would be no recoil?

salty

[berkbw]

So -- it's not the gas pressure holding the lugs in engagement, it's the continuing friction of the round in the bbl. Is that now correct?

b-

[1911Tuner]

If there were just one ball and it was spiked in a stationary position so as not to move, there would be no recoil?

No. Both must be unable to move before there would be no recoil. If only one is unable, the cannon then becomes a normal gun. The fixed ball is the breechblock and the movable ball the projectile. The cannon would fire like any normal cannon.

So -- it's not the gas pressure holding the lugs in engagement, it's the continuing friction of the round in the bbl. Is that now correct?

It's both. The pressure pushes the bulllet and the slide in opposite directions. The barrel suffers forward drag through friction, and tries to remain forward whild the slide exerts a rearrd pull on it. The lugs are engaged...meshed...and bear against one another in a shearing action.

Do the "Cork in a Pipe" demo in your mind. The cork is the bullet. The hand grasping the pipe is the slide. The grip exerted on the pipe represents the locking lugs.

[Greyswindir]

Thanks for the compliment Tuner! :D

But....you said:

Almost completely correct! Very good, young grasshopper...but you didn't quite finish.

Then:

WHY...does the bullet's influence delay the slide's rearward acceleration?

I thought the delay came from the locking of the lugs...Or did Log finish it up by adding:

After it left of course, do you think Mr. Bullet is a quitter? No! After he grabbed the rope there was 4" left and he held on right to the end.

So I'm still missing one little bit of information then?

[1911Tuner]

thought the delay came from the locking of the lugs

No. The lugs only tie the barrel and slide together. The delay comes from the frictional resistance between bullet and barrel...with each one moving in opposite directions...and each one resisting the other's movement. The slide is delayed because it's pulling the barrel via the lugs. Whatever resists the barrel also resists the slide.

It might help to think of the barrel and slide as one part while they're locked and moving backward instead of two. Once the barrel links down...then they become separate parts that can't influence one another.

[Greyswindir]

Ahhh...,

One more parameter of motion that I didn't think of...lots of things happening at the same time in subtle and relative ways.

Thanks Tuner!

[1911Tuner]

lots of things happening at the same time in subtle and relative ways.


Yup. That's a piece of the puzzle that most don't consider...or just flat don't believe...but it's there. The amazing thing is how Browning managed to figure all this out in his head...and get it to work within the short time frame that it takes the slide to move a 10th of an inch. The interesting thing about John Browning is that he didn't ahve an engineering degree, and according to the reports from the people who worked with him at Colt and FN...he was fairly proud of that fact.

When considering the physics of the event...keep one thing in mind.

Nothing means everything, but everything means something...and anything that can influence the acceleration of the bullet OR the slide will do just that.

"Objects in motion will remain in motion." Here, Newton is describing the conservation of momentum.

UNLESS...the object in motion is influenced by an outside force.

Outside force meaning anything outside the system that has the opportunity to influence the moving object.

Outside forces acting against the slide also include the recoil spring...rail friction...and even wind resistance and atmospheric pressure....or a gnat that lights on the slide at the instant of its rearward movement. It all means SOMEthing...to some degree, and nothing can be ignored or discounted.

[Greyswindir]

For some reason I failed to consider that the action of the bullet friction on the barrel effected the system on more than one level. The first effect that I knew was taking place (through our earlier conversations a few weeks ago) was the Newtonian axiom "Every action has an equal and opposite reaction", meaning the pressure of the powder igniting had an effect on both the barrel and slide at the same moment. Along with causing a dual effect in opposite directions I failed to think about the secondary effect that the bullet friction was having on delaying the slide's rearward motion.

I just failed to think more critically about the secondary effects, focusing more on the primary effects that I already knew were happening, which was the locking action that the bullets friction caused between the slide and barrel lugs; horizontal engagement and locking caused by Newton's axiom.

If I wasn't so focused on the primary effects I might have focused more on the more subtle aspects, which was actually what you were telling us to do by giving us that first hint! What was so easily missed by myself and others was the secondary effect of bullet friction, which was delaying the slide's motion besides locking the breech.

Slide and barrel become one unit until the moment unlocking begins.

Pretty awesome stuff Tuner! :appld:

P.S.,

The interesting thing about John Browning is that he didn't have an engineering degree, and according to the reports from the people who worked with him at Colt and FN...he was fairly proud of that fact.

Just goes to show that degrees aren't necessary...There are a lot of "paper tigers" walking around in this world. I'd go with experience over the general knowledge that is taught in most colleges any day. That doesn't mean degrees are useless, because they're not. But it does prove that a little piece of paper doesn't make a man an expert. Intelligence, innovation, experience, and genius are what really make a person a genuine expert.

[berkbw]

Thanks, Tuner..
b-

[1911Tuner]

I guess the best way to sum all this up is...

Nothing is everything, but everything is something.

That it's not easily seen or understood doesn't mean that it doesn't exist or that it's not an influence...no matter how seemingly insignifigant.

Newton's 3rd law of action and reaction applies in both directions...whether pushing or pulling.

No matter what unseen, misunderstood, or complex things take place during an internal ballistic event...none of them can override the laws of physics...or even suspend them for a brief, immeasurable instant. Those laws are not negotiable.

[Greyswindir]

Hi Tuner,

What is interesting to me is that Isaac Newton received the lion's share of the credit for discoveries and observations concerning gravity, heavenly bodies, and their orbits and motion and how they effect the earth.

Copernicus really laid down all of the ground work, then Newton came along and put it in terms people could understand. Don't get me wrong, Newton was a brilliant man and deserves all of the credit for his own research and his own discoveries, but doesn't deserve the credit for the discoveries and observations made by of all the great minds that came before him. Copernicus being at the top of that list, along with another fellow that I am not remembering right now.

Most don't realize that Newton was an alchemist, was obsessed with the Holy Bible and believed that the scriptures contained literally all of the knowledge in the universe, in a coded form. He spent a massive amount of his time trying to unlock and decode the secrets of the Torah and the other books of the Old Testament.

Thank God for men like Copernicus and Newton, without them we may not have had the opportunity to discuss all of the wonderful aspects of 1911 function and how physics help us to understand the mechanics involved in its operation.

[Hawkmoon]

Yeah -- And Newton didn't have to overcome the problems of having the Catholic Church label his writings "heresy." It was only in the very late stages of the 20th century that Rome finally backed off that position and announced that they no longer considered Copernicus' works to be heretical.

[Greyswindir]

Good point...He didn't have to worry about getting strapped into an Iron Maiden and enduring torture until he renounced his "heretical views"!

[beckman]

Hi, new guy here, and I'd like to say that I find both the forum in general, and this discussion, to be very interesting.

I've always wondered how much of an effect the added mass of the barrel had upon retarding the slide's rearward travel while the two are locked, in effect making the action similar to that of a delayed blowback. Or, is the short recoil, itself, the only important factor, providing reliable extraction without case bulging, etc? I've never really been convinced one way or the other.

I've read other threads here discussing that the barrel is pulled forward due to the bullet's forward travel. Honestly, I had never considered this factor before. It certainly makes sense that this would further retard the slide's rearward motion. The real question is one of proportion. How great are these factors compared to the total equation?

Interestingly, I found a description of an experiment conducted which may put the factor of bullet resistance in the barrel into perspective:

"I reamed an old barrel to .500 inch diameter, leaving only the chamber shoulder and a smooth bore that was roughly .0245 inch per side larger than the .451 diameter bullet.

I loaded a handloaded round consisting of 6 grains of Unique and a 230-grain JRN bullet...and fired the gun. The slide cycled normally. The felt recoil was also within normal range. The bullet disappeared in a hardwood tree. Another did likewise in hard, dry Piedmont NC clay. In this barrel, there was no gradual building of pressure. The bullet velocity was obtained in the chamber alone...with no resistance provided by any rifling. The gun felt and cycled in normally. It would have difficult to tell the difference in even a back-to-back blind test. The bullets would have ruined your day had you been hit by one."

The above was posted by 1911Tuner here:
http://forum.m1911.org/showthread.php?p=503374#post503374

Does the forward pull of the barrel, caused by the bullet's resistance, have an effect? Probably, but if the above experiment is relevant, the effect is relatively minor.

I would like to add that you have a really great forum here and it's good to see a mature discussion about the inner workings of the 1911 design. I'm very impressed with the knowledge and expertise of the contributors here.

[Greyswindir]

Hi Beckamn,

I agree with you bigtime! Some of the threads here are of a quality not found on other 1911 specific forums. Most of that is because of quality moderators (some of which are engineers and such) and some very knowledgeable members, like 1911Tuner, Jim Watson, Jerry Keefer, Log man, ect. Sorry if I left any of you guys out, there are just so many excellent guys that contribute here it is hard to remember all of you!

And last, but of course not least, John Cardimas, who started this forum and made it into a great place for mature discussion. He doesn't tolerate any form of trolling or name calling and runs the cleanest forum in the western hemisphere!

Nice to meet you and I hope you add to the great atmosphere of this forum beckman!

-Grey.

[log man]

Does the forward pull of the barrel, caused by the bullet's resistance, have an effect? Probably, but if the above experiment is relevant, the effect is relatively minor.

Welcome. First, I believe you would have to understand what was the relevance of the experiment. Whether the pressure builds initially or as the bullet travels through the bore. And it did show that the greater percent of pressure is built up in the beginning, as the gun cycled normally.

However this is not too say, nor was said, that the bullets velocity or accuracy was effected by this experiment. Improved accuracy is a result of the delayed blow back, and is controlled by the bullets forward pulling of the barrel by the friction it incurs. This is not to say that it reduces recoil, just retards it enough to exit on target. And that is relevant. :appld:

LOG

[1911Tuner]

Welcome aboard, Beckman. Very good questions.

I've always wondered how much of an effect the added mass of the barrel had upon retarding the slide's rearward travel while the two are locked, in effect making the action similar to that of a delayed blowback.

It would be in direct proportiin to the ratio of barrel mass to slide mass. The slide weighs about 15ounces. The barrel...about 5-6, depending on the actual steel alloy and the caliber. A 9mm 5-inch barrel is heavier in proportion to the slide than a .45 barrel.

Or, is the short recoil, itself, the only important factor, providing reliable extraction without case bulging, etc? I've never really been convinced one way or the other.

Ned Christiansen once conducted an experiment not related to the slide delay, but essentially anwered your question...at least in part...when he repeatedly fired a pistol with no recoil spring present. No problems were reported, though I'm unsure of whether he checked for case bulge. If there had been any signifigant bulging, I'm sure he'd have noticed.

The above was posted by 1911Tuner here:
http://forum.m1911.org/showthread.p...3374#post503374

Does the forward pull of the barrel, caused by the bullet's resistance, have an effect? Probably, but if the above experiment is relevant, the effect is relatively minor.

Of course it did. It would have to, since the reamed barrel wouldn't undergo any slowing/delaying drag effect from the bullet. That demo was done to ilustrate the point of the greatest recoil impulse...and that it's not dependent on total muzzle velocity.


Does the forward pull of the barrel, caused by the bullet's resistance, have an effect? Probably, but if the above experiment is relevant, the effect is relatively minor.

Well...The effect would be fairly signifigant, probably causing at least as much delay as the mass of the slide itself. Try manually pushing a bullet through a barrel from breech to muzzle. This drag effect is very short, however...lasting only until the bullet separated from the muzzle...lasting for less time than the barrel's added mass, which continues to be a part of the slide until the two are completely separated by the link. That distance hasn't really been measured, but you can figure it at around .150-.160 inch of slide travel and not be too far off the mark. My bet would be that the initial resistance offered to the bullet in entering the barrel would have the greatest influence at that phase, since it overshadows the resistance of all the other factors combined...and that resistance would continue for as long as the bullet was preset.

The key is to remember that nothing is everything, but everything is something. No one thing determines the function, but the combined effects of many. Slide/barrel mass. Recoil spring load and mass. Mainspring load and hammer mass. Even larger, more massive sights change the whole effect. Anything that has the opportunity to get in the way WILL get in the way.

[berkbw]

I would think (dare I use that word here?) that the period of greatest resistance between bullet and bbl would be during the swaging of the bullet by the lands. I have no feeling what the differences in chamber dia., shape of round, and the profile of the start of the lands would affect the resistance. I WOULD expect that the initial resistance would fall off and remain mostly constant for the remainder of the trip out of the muzzle.

This is technically (tho maybe not practically) interesting and measurable. I do not have the resources to perform these measurements. Just designing and debugging the test bed would be an interesting challenge.

Berk

[log man]

Hey. Berk, it's okay to think, and pretty darn hard not too.The idea of a bullet being engraved and spun up to speed immediately being the moment of most resistance is sound thinking. An attempt to ease the bullet into the engraving process and spinning it up with minimal reduction in velocity is the intension of the AET barrel. Where the lands begin parallel to the bore axis and spin up the bullet after engraving, gradually. Looking through one of these barrels makes just about everyone who does so smile.

LOG

[beckman]

Tuner,

Thank you for reply and for your welcome. Although I have great respect for your knowledge, experience and troubleshooting wisdom, I have some issues with the points that you raised.

Ned Christiansen once conducted an experiment not related to the slide delay, but essentially anwered your question...at least in part...when he repeatedly fired a pistol with no recoil spring present. No problems were reported, though I'm unsure of whether he checked for case bulge. If there had been any signifigant bulging, I'm sure he'd have noticed.

I fail to understand how the above experiment could have anything to do with the question about whether the short recoil system's main feature is that it provides easier extraction and/or prevents case bulging compared to straight blowback. My understanding of the above experiment is that an otherwise standard 1911-type pistol was used and the only modification was that there was no recoil spring.

In the above experiment, the barrel and slide were still locked normally. The short recoil system operated almost normally. The lack of a recoil spring probably has only a minor effect upon the initial unlocking phase of the cycle, after ignition, given that the action of cocking the hammer requires more energy than does the initial compression of the recoil spring. This is obvious to anybody who racks the slide both with and without the hammer cocked. As you've pointed out in other threads, this effect is even more pronounced with a small radius FPS.


Of course it did. It would have to, since the reamed barrel wouldn't undergo any slowing/delaying drag effect from the bullet. That demo was done to ilustrate the point of the greatest recoil impulse...and that it's not dependent on total muzzle velocity.

I'm not clear about what you are referring to when you say, "of course it did." The fact remains that in your experiment, you've observed that the pistol will function normally without "any slowing/delaying drag effect from the bullet," when you ream out the barrel. You have, according to your own claims, eliminated the one variable under discussion -- the bullet's resistance in the barrel -- with little effect upon the functioning of the weapon.

This reminds me of the controversial Blish Lock in the early Thompsons. Maybe it did have some effect, but later Thompsons functioned without them.

Frankly, I'm not completely convinced that your barrel-reaming experiment did completely eliminate bullet resistance in the barrel. Although your experiment is probably relevant to our discussion, I would be more certain if the barrel was a tight-fitting smooth bore, with very little gas blow-by.

Well...The effect would be fairly signifigant, probably causing at least as much delay as the mass of the slide itself. Try manually pushing a bullet through a barrel from breech to muzzle...

I'm not clear about how you determined the delay-effect of bullet's resistance. Is this simply a guess? You may be correct, but I would like to know how you arrived at this estimate.

As far as manually pushing a bullet, I've done this -- in a few pistol calibers, but only partway. I've also fired a Glock 9mm with my palm pressing the back of the slide, keeping it closed. What I've felt in both instances is subjective and meaningless. I felt less on my palm when I fired the Glock than the subjective about of pressure required to manually push a 9mm bullet through the rifling. The reality is just the opposite. What I felt on my palm when I fired the Glock was equal to the energy required to push the bullet through the barrel PLUS whatever muzzle energy the bullet attained. My subjective impression was wrong.

This raises an important point we KNOW that the 1911 will develop some 370 FPE at the muzzle -- after the rifling. As a proportion, how much has it been reduced due to the rifling? 5%, 10%, 1%? This is the basic question that I've discussed before. Is the bullet-resistance effect significant, or is it similar to putting on a more massive rear sight? Most importantly, how do we know?

[1911Tuner]

I fail to understand how the above experiment could have anything to do with the question about whether the short recoil system's main feature is that it provides easier extraction and/or prevents case bulging compared to straight blowback. My understanding of the above experiment is that an otherwise standard 1911-type pistol was used and the only modification was that there was no recoil spring.

Ned's demo was aimed at showing the effect...or the lack thereof...of the recoil spring in determining barrel unlock timing. That the pistol functioned normally...albeit with higher slide velocity rearward...suggests that the recoil spring is actually more of an action spring than anything else.


n you ream out the barrel. You have, according to your own claims, eliminated the one variable under discussion -- the bullet's resistance in the barrel -- with little effect upon the functioning of the weapon.

My experiement was designed to show that the bulk of the total recoil impulse comes early, and not...as some believe...builds up as the bullet traverses the bore. That the delaying effect of the bullet in the barrel had no adverse function was due partly to the fact that it didn't need peak pressure to function. Pressure was likely far below the normal levels. Had the bore offered the normal amount of resistance to the bullet with pressures that low...short recoil would have likely caused a malfunction. To sum it up...The demo was intended to show that about 90% of the recoil impulse and total velocity occurs in the first half-inch of bullet travel. Later chronographing with a revolver with just the forcing cone in the frame has borne this out.

I'm not clear about how you determined the delay-effect of bullet's resistance. Is this simply a guess? You may be correct, but I would like to know how you arrived at this estimate

No. It's a physical fact. Newton's 3rd law works in both drections...pushing or pulling. It's also a fact that whatever frictional resistance exists between two objects in contact is imposed on both in equal measure. If you drag a heavy object across the floor...both the floor and the object "feel" equal frictional forces.

So...by natural extrapolation...we can state that whatever resistance that the barrel offers to the bullet, the bullet also offers to the barrel. Because the barrel is moving backward at the same time that the bullet is moving forward...each one "feels" the resistive force imposed by the other.

Frankly, I'm not completely convinced that your barrel-reaming experiment did completely eliminate bullet resistance in the barrel.

t probably didn't completely eliminate it...but it probably brought the actual frictional forces to a level that would mean next to nothing in comparison what they would be in a normal barrel.

As far as manually pushing a bullet, I've done this -- in a few pistol calibers, but only partway.

To get a better understanding as to how much resistance that really is, simply repeat it with the muzzle on a bathroom scale...and if you can push a jacketed bullet through a rifled barrel from chamber to muzzle...by hand...Well, yer a better man than I am, Gunga Din.


This raises an important point we KNOW that the 1911 will develop some 370 FPE at the muzzle -- after the rifling. As a proportion, how much has it been reduced due to the rifling? 5%, 10%, 1%? This is the basic question that I've discussed before.

None...unless the compelling force from the expanding gasses drop to the point that the bullet actually starts to slow down...and that can happen. I read of an experiment once in a magazine article in which the author started with a 26-inch rifle barrel in .308 caliber, and chronographed several handloads with varying powder burn rates. Each time he finished, he lopped off an inch of barrel...recrowned it...and repeated the tests. With a few of the faster powders, he was able to get higher velocities as the barrel got shorter. Of course, this eventually reached a point of diminishing return, and below a certain length...the velocities began to drop. In addition, he was also able to get higher velocities with the fast powders in the shorter lengths than with the slow powders that produced top velocities when the barrel was long.

As long as the powder gasses are expanding, and accelerating the bullet...it will be moving as fast as it's ever going to at the point of exit, assuming a powder burn rate that's suitable for the application. In order for the bullet to lose energy, it would have to lose velocity in the barrel. As to the question: "Is there a point in the barrel that the bullet is actually moving faster than it is at the muzzle?" We'll probably never know unless we conduct a similar experiment. Not as easy with an autopistol...but doable.


I felt less on my palm when I fired the Glock than the subjective about of pressure required to manually push a 9mm bullet through the rifling. The reality is just the opposite. What I felt on my palm when I fired the Glock was equal to the energy required to push the bullet through the barrel PLUS whatever muzzle energy the bullet attained.

I think you're confusing force required to overcome friction with slide momentum.
You imposed another outside force on the system. Since the slide's momentum must be equal to that of the bullet...minus the outside forces that are trying to bring it to a stop...you got a jolt that was somewhat less than what the bullet was carrying...or conserving, if you prefer.

Momentum must be conserved. An object in motion will remain in motion unless and until it encounters an outside force. Since everything was working to destroy the slide's momentum and restore equilibrium...the recoil spring...the striker spring...and the bullet's delay in allowing the barrel to move backward...while the only signifigant outside forces working against the bullet were friction and air pressure ahead of it in the barrel.

You can demonstrate the bullet's delaying effect pretty simply. Attach a rope to a cork that fits tightly in a plastic pipe. Pipe in one hand and the rope in the other...apply gradually increasing force until the cork slips. At the same instant, the pipe will slip in the other direction...so that while the cork is moving through the pipe, the pipe is being pulled off the cork. This is essentially how recoil works. While the bullet is being driven through the barrel, the barrel is being pulled off the bullet.

Once you've got both cork and pipe in motion,continue to pull them apart...and you'll feel resistance in both directions.

Because...

Whatever resistance is offered to the cork BY the pipe, is also offered to the PIPE by the cork.

[beckman]

Tuner,

Thanks for your reply. I appreciate the your input. Unfortunately, it appears that we are not communicating very well. Let me try to clearly repeat my main points, so as not to further confuse the matter:

1. I agree that the bullet resistance must have some effect. I have agreed from my very first post. My question is: How much in proportion to the total energy involved and how has this proportion been determined?

2. Your own experiment with the reamed barrel gave some indication as to how much the bullet resistance affected function. It doesn't matter what the experiment was "designed" to show, what matters is what it DID show, given your own statements that:
a) There was no resistance in the barrel.
b) The bullet achieved an estimated 90% of normal velocity.
c) The pistol functioned normally.

If the bullet achieved 90% of its normal energy without rifling, then how much of the normal, 100%, is used to overcome the rifling's resistance?

The effects from your experiment are very similar to those old stories about how a 1911 will still function with a completely pitted bore. In those stories, there was no rifling and little resistance, but the pistol still functioned.

3. How did you determine that the delay effect is "fairly significant, probably causing at least as much delay as the mass of the slide"? How did you calculate that it is at least equal to the delay caused by the mass of the slide?

4. Regarding your claim that one can somehow estimate the amount of the bullet's resistance by subjective feel through pushing a bullet through a barrel, my point was that this does not give us an idea about the energy required. More importantly, it doesn't give us an idea of the proportion of energy involved in relation to to entire system.

As I stated before, I HAVE pushed a bullet through a barrel and I've felt it. Now, in order for you to give me an idea of the amount of energy involved, tell me how it "feels" when you've thrown that a similar bullet at 830fps (a 100mph fastball moves at 147 fps or so). Subjective feeling in these experiments tells us nothing. It is comparing donuts to trucks. That was my point when I discussed the feel in my palm when I pushed the slide closed and fired the Glock. It told me nothing, but it was definitely MUCH MORE energy than was required to push the bullet through the barrel.

5. Do we at least agree that Ned's demo has no relevance to our discussion?

Again, I do not dispute that there is some effect, the question is one of proportion. You say that it's significant. I ask, "How significant, and how do you know?" Pulling a cork through a tube or pushing a bullet through a barrel (even a barrel on a bathroom scale) doesn't give me a realistic quantifiable answer, nor does it give me a sense of proportion in relation to the entire amount of energy involved.

[1911Tuner]

If the bullet achieved 90% of its normal energy without rifling, then how much of the normal, 100%, is used to overcome the rifling's resistance?

When pondering this one, remember that without the resistance incurred by swaging down and being engraved by the rifling that the pressures never reach normal peak levels. Since the violent rise to peak pressure is where the driving force comes from...for both bullet and slide. Whatever force is required to propel the bullet is visited on the slide. If it takes X units of force to accelerate the bullet, then X units of force are imposed on the slide. Force forward equals force backward. Always.


3. How did you determine that the delay effect is "fairly significant, probably causing at least as much delay as the mass of the slide"? How did you calculate that it is at least equal to the delay caused by the mass of the slide?

Logic. It requires more force to break the brass case's grip on the bullet than it takes to get the slide moving. Niemi proved that several months ago. It requires many times more force than that to start the bullet into the rifling...and the bullet to bore resistance probably accounts for more than the slide's effect...much more. Half was a conservative estimate, mainly intended to avoid comments of: "No way!" Yes...Way.

Again...force an unmarked bullet though the bore from chamber to muzzle. You can yank the slide fully rearward as fast as it moves when firing without garguantan effort. You can't accelerate the bullet from zero to 800+ fps manually...unless you're a MUCH better man than I am...or any that I've ever seen.


It told me nothing, but it was definitely MUCH MORE energy than was required to push the bullet through the barrel.

You're still confusing frictional resistance and force applied with momentum. When you push a bullet through, all you feel is pressure against your hand from the resistance. The momentum developed by the bullet at...what...2 inches per second is tiny compared to the slide's momentum when operating at full speed. Kumquats to tangerines. Momentum is Mass X Velocity.

Bear in mind, too that the force required to accelerate an object slowly is a much different matter than trying to accelerate it quickly, and it requires much more force to accomplish that. Any 10 year-old can throw a baseball from the pitcher's mound to home plate. Throwing that same baseball the same distance hard enough to cross the plate at 100 mph is a different ball game...if you'll excuse the pun.

See Newton 1A: Objects at rest tend to remain at rest. The harder and faster you try to accelerate the object, the more it resists that acceleration. This also applies to overcoming frictional resistance and can can be observed with a rifle...handloaded ammunition...and a chronograph. A bullet that exits a rifle barrel at 3,000 fps will lose a greater percentage of its initial velocity at 100 yards than the same bullet that exits at 2500 fps. The reason being that it hits the air harder, and the resistance of the air is greater on the faster bullet.

Pulling a cork through a tube or pushing a bullet through a barrel (even a barrel on a bathroom scale) doesn't give me a realistic quantifiable answer, nor does it give me a sense of proportion in relation to the entire amount of energy involved.

It wasn't intended to give you a "quantifiable" answer. It was intended to give you an idea of the forces involved. One more time...you can move the slide by hand as fast as it moves when you fire the gun. You can't accelerate that bullet from chamber to muzzle to a velocity of 800 fps by hand.

The cork and pipe demo is only intended to show that there is a resistance in both directions.

[beckman]

Tuner,

Thanks again for your reply.

I apologize for taking up so much of your time and distracting you from providing your very valuable advice and troubleshooting to the forum members. It may not seem so, but if I did not value your knowledge and expertise, I would not engage you in an internet discussion about the functioning of the 1911.

However, I still have significant issues regarding our discussion.


It requires more force to break the brass case's grip on the bullet than it takes to get the slide moving. Niemi proved that several months ago. It requires many times more force than that to start the bullet into the rifling...


Any handloader who has accidentally loaded a round without powder has seen EXACTLY how much energy, relatively speaking, is required to move a bullet partway through the barrel -- it is very little. Maybe it feels like allot when you have to push the bullet manually but, as I've said before, that test is irrelevant because it does not give an idea of proportion. Proportion is the main issue in this disussion.

You can't accelerate the bullet from zero to 800+ fps manually...unless you're a MUCH better man than I am...or any that I've ever seen.

That's my point, exactly! You CAN'T manually propel a bullet to 830fps. Even if you could, you wouldn't get an idea of the relevance of the "manually push a bullet through barrel test." You can't realistically compare the amount of energy used in a handgun with the same task performed manually. It is a meaningless comparison. How things "feel" does not put it into proportion.

Again, this entire discussion is one of proportion. You claim that the bullet's resistance through the barrel is a significant and important aspect of the functioning of the 1911-type weapon, and most likely all short recoil weapons. I agree that the resistance has an effect, but I question the claim regarding its importance, based partly upon your own experiment with the "no rifling" barrel which still provided normal functioning and 90% velocity. If the rifling resistance effect was important, a 1911 with no rifling would not function properly.

In addition, as stated above, a primed-only case provides enough energy to move a bullet partway through a barrel. I think that we can all agree on this point. It is clear that a primer-powered projectile has very, very little energy, relative to a full-power load. This gives us another idea of the importance of the rifling resistance effect in the entire system: It is minor.

[1911Tuner]

Any handloader who has accidentally loaded a round without powder has seen EXACTLY how much energy, relatively speaking, is required to move a bullet partway through the barrel


How do you determine exactly how much energy is expended by a squib load? I think you'd be a bit surprised at how much is generated by just the primer. Again...Niemi showed that it requires about 100 pounds psi to get the bullet to break free of the case's grip...and that from a handloaded round without an asphalt cement sealer. Add a grain or so of a quick pistol powder, and you can probably figure at least 2-3 times that generated by the primer.

It is clear that a primer-powered projectile has very, very little energy, relative to a full-power load.

Based on what comparison? Compared to a fully charged case...yes...but there's still enough to drive it into the rifling part-way. I'll suggest again that you go push a bullet through a barrel while the muzzle is pressing on a bathroom scale to see how much sheer force is required. No hammering. Just push it.

All we know for sure is that the frictional resistance imposed by the barrel will overcome the force driving the bullet and bring it to a halt...at some point. Lead bullets will go deeper than jacketed bullets. Bullets with thick jackets will stop sooner, as will bullets with hard cores...all else being equal.

It seems that you've made several assumptions on force delivered and resistance offered. We can guess all we like...but until we put it to the test, we don't know exactly what magnitudes we're dealing with. Or...as a wise, wise man once said:

"I only know what I can measure."

All else is conjecture.

[log man]

BECKMAN, Would you please explain how the 1911 functions in regard to delayed blow back, and how that is accomplished by design. If the bullets frictional drag in the barrel isn't significant what is? And since you propose that it isn't significant, then why have upper lugs on the barrel and slide? What purpose or function could they serve if not too delay the slides rearward movement, through the barrels forward thrust generated by the frictional forces of the bullet? Or as it seems by your posts you believe the 1911 is a delayed blow back firearm, retarded only by the weight of the barrel being pulled to the rear for the .250" it takes to link down?


LOG

[1911Tuner]

Log...Before we pounce, let's have a look at the only real difference between the two. Namely...The method in delaying the breech opening.

Back in the 80s, Llama made a miniature 1911 in three calibers. .22 Rimfire... .32 Auto...and .380 ACP. The .380 pistol was available in two versions.
One was a straight blowback, and the other a true-to-Browning locked breech/short recoil pistol with a tilting barrel and falling link. Outwardly, the two were identical.

The major difference that everyone noticed was that the blowback version had a ridiculously strong action/recoil spring, making it difficult for even strong hands to manipulart...while the other was a creampuff in that function.

Since the slides were identical in mass and weight...there were even some blowback models that apparently used slides from the LB/SRO model, because the lug cuts were present...the spring was necesarily far stronger than would have been needed had the slide mass been greater. So...The diminutive little pistol depended solely on spring strength to effect the delay.

The other thing that was apparent in the blowback pistols after some use was that...as the spring started to grow weaker...bulged cases started to appear. The conclusion was that...because the spring was all that stood between safe function and a dangerous condition was a pound or two in spring strength. You could scarcely feel the difference in hand-cycling one of the guns with a new spring, and one with a spring tired enough to allow a slightly early breech opening.

Since Ned Christiansen has long since put the spring argument to bed concerning the locked breech/short recoil pistol...we can safely draw the obvious conclusion that something signifigant is at work there...because if the slide moved so fast that the barrel reached the point of linkdown while the bullet was still present and the pressure still at a dangerous level...the link would stretch and the corners of the barrel and slide lugs would show damage.

So...the recoil spring is only a small part of the slide's delay. We've seen that the preload on the static slide is in the neighborhood of 8-10 pounds. A 10th inch f compression would add very little to that resistance.

Neither would the mainspring alone be a signifigant factor in achieving sufficient delay.

Neither would adding an extra 30% of mass to the slide via the barrel be enough for a .45 caliber pistol...even though it probably would be for the little 9mm Kurz. The recoil impulse for that caliber is low enough to make that viable...but not for the 9mm Parabellum or the .45 ACP.


So...What else is there, except the bullet's drag on the reciprocating assembly?

[log man]

So...What else is there, except the bullet's drag on the reciprocating assembly?
Exactly!

Exactly!

I understand completely and have come too more fully understand the why of the differences. I have several small caliber direct blow back pistols and they are as hard to pull back as a 1911 .45. I've also felt/compared the recoil spring on a HK P7M8, which is a gas delayed direct blow back, to a 9mm 1911, big difference, the 9mm 1911 is much easier to pull back. This of course is evidence of the effect/benefit of the 1911 locked breach delayed blow back design.And the effects of the frictional drag of the bullet in the barrel. :)

LOG

[niemi24s]

Here's some forces needed to slowly move some bullets starting with a clean, dry barrel. The barrel was (unfortunately) not cleaned between tests. The bullets are an H&G 130 (BHN = 14 16 or so) and a CCI BB JRN, both in Federal cases. Only one of each was tested.

The first number is the force needed to just begin moving the bullet out of the case. The second, is the range of forces needed to get the bullet into the leade, past the leade, free of the case and into the rifling. The third is the force needed to move the bullet once completely into the rifling.

H&G 130: 140lbs; 180 to 200lbs; 155lbs
CCI BB JRN: 110lbs; 120 to 170 lbs; 90lbs

Don't know whether the forces for the CCI BB JRN are lower because the bullet was a pull or because the barrel was not cleaned prior to its test. Could be due to both, I guess. May be due to something else too!

Also don't know if this has much to do with what's being discussed, but I see a lot of references to "bullet drag on barrel" and I already had the info.

Cheers

[Edited to change BHN in paragraph 1]

[1911Tuner]

It has a lot to do with it, Dan...and thanks again for the effort. Your inquisitive mind is invaluable.

The gap from 170 to 90 pounds for the CCI bullet is most likely due to the core alloy...softer than the other. Jacketed bullets with swaged lead cores vary as to antimony and tin content. The CCI Blazer line...being a bargain basement line...probably has a nearly pure lead core in order to hold cost of production down. Costwise...A few tenths of a percent is neither here nor there for a single cartridge. For 30 million cartridges , the savings is meaningful.

So...Going to the H&G hardcast bullet that required 180-200 pounds to start it into the rifling. Because Newton 3 is in full force whether pushing or pulling...and because force is equal in both directions...that means there's an equal resisting force imposed on the slide. If it had been a jacketed bullet with a harder core than the CCI...those numbers would have gone up...and depending on jacket thickness...they may have jumped a signifigant amount.

180-200 pounds pretty well trumps any resistance offered by the recoil spring...which imposes only about 10 pounds at the outset, and precious little extra with a 10th inch of compression. Factor in the mainspring with maybe 15 pounds at static preload...and that leaves slide and barrel mass. Cock the hammer to eliminate the mainspring. Yank the slide as fast as you can against the recoil spring's resistance...and you'll notice that there's little if any difference in the slide's acceleration than when the gun is fired with a standard hardball-spec round. (Go stand to the side and observe the slide with a friend firing the gun. You can see it move.

So...If you can accelerate the slide to near-operational velocity by hand...and a strong hand can do it even with the hammer down...that leaves bullet drag as the major player in this equation.

You may draw your own conclusions. I already have.

[Greyswindir]

Hi guys,

I'm kinda at a loss as to what beck is trying to argue in relation to what has already been posted by pretty much all of us. Not that majority is right simply because it is majority, but because physics and a little common sense prove out what is happening during the cycling of a 1911 pistol.

Primers are very powerful and have actually killed people. An actor during either the '50's or '60's died from just a primer going off and a small fragment of primer hitting him in the head...well the guy is dead. That proves that primers are powerful and dangerous!

Tuners experiment /example with the cork and the tube does adequately explain what is going on between the bullet and the barrel. The action is simply slowed down; the "feel" is relevant and shouldn't be discounted out of hand. Proportion is the wrong word to use, scale would probably be more accurate in this situation. And scale models are used in many various industry tests, whether we're trying to learn something about a stationary object or we're trying to learn something about a moving object.

If I'm wrong than Goddard was wrong, so was Da Vince and countless other brilliant inventors. Scale models, whether we're talking size, weight, friction models, whatever, are extremely valuable and often produce data that reflects how the "real" model will behave. Past experiments give us a good base line to postulate from and form new hypothesis' and theories.

Back to the primer, a squib load, and the rifling. It's not a question of whether or not the resistance is minor, but how the resistance effects the system as a whole. A car traveling at speeds up to and over 200 miles per hour will launch off of the road because of hitting a small stone.

Let's use a current example floating around on the History Channel:

Scientists are thinking up lots of different ways to deflect, destroy, etc., a meteor or comet that is on a crash course towards earth. Meteors are pretty massive and dense, even the smaller ones. Most of the ideas have been geared towards changing the trajectory of the meteor rather then trying to blow one up.

The scientists have concluded that removing a minute amount of material from the meteor would be enough to change the trajectory enough so it would miss the earth. Small idea that causes a big effect. A small amount of material is removed yet it changes the trajectory of massive, dense object moving at speeds far faster than a bullet.

Other ideas include solar sails, remote controlled "diggers", rocket propulsion, etc. Either way, the point is that a small change in any system can result in large changes to said system. So though the effect of the bullet on the barrel may seem small it can and does effect the function of the gun in major way.

Understanding these effects depends largely on personal perspective. Regardless if we're dealing if fact, or a very accurate hypothesis based on past data, questions and/or arguments will always remain for those who cannot or do not wish to interpret the data based on a solid understanding of physics or direct experience. Basically it's called nit picking!

It's possible that somewhere out there in the universe there is a moon orbiting a planet that is made of green cheese. It may be possible but that doesn't mean it is probable. It is not something that can be disproved, even though all of the current theories on how planets and stars form have nothing to do with green cheese. You can argue almost anything but without a solid basis in reality (the science of physics) you're really getting into philosophy. And philosophy doesn't have a place in this discussion, at least I don't think philosophy is relevant to this discussion.

[niemi24s]

Just changed the BHN for the H&G 130 in Post #56 from 14 to 16 after a quick check of my records.

And, FWIW, the BHN for a CCI BB JRN from the same box tested at BHN = 11, the test done on the base with the 0.005 inch thick jacket/cladding/plating intact. However, I'm not sure about the validity of a Brinell test on a composite material such as this.

Did not test the hardness of just the lead core, but will do so if the info might be of some use. Just let me know. Oh, what the heck - now my curiosity's been piqued - I'll test it after I get some sleep. Stanley Cup finals play hob with my beauty rest! :)

Cheers

[beckman]

Tuner,

I really think that we are having a problem communicating here.

It is clear that a primer-powered projectile has very, very little energy, relative to a full-power load.
Based on what comparison?

The comparison is of the energy generated by a primer alone compared to the energy produced by the combination of the primer and powder. The primer may generate a "surprising" amount of energy, but it is minor compared to that generated by a full charge. A million dollars may be allot, but it is a very minor part of the annual U.S. budget. I will say again, it is all a matter of proportion: the energy required to push the bullet through the barrel relative to the total energy.


Compared to a fully charged case...yes...

Finally, we are in agreement on something!!!


We can guess all we like...but until we put it to the test, we don't know exactly what magnitudes we're dealing with. Or...as a wise, wise man once said:

"I only know what I can measure."

OK, let's look at Niemi's claim that it takes a maximum of 200lbs to move a bullet through the barrel. I'm not clear whether this is PSI or total pounds, but in order to give you a break, I'll assume that it's total pounds and I'll convert to PSI. The sectional area of a .45 bullet is .160" so we multiply 6.25 by 200lbs in order to get PSI, 1250psi. Is that allot? It might "feel" like allot if you try and push it manually. But not in comparison to the 21,000psi at work in the .45 ACP, it's only 6% of the total pressure, and that's my entire point.

You wanted a measurement, I gave you one -- using data which you've already accepted.

Again, I have NEVER argued that there is no forward thrust in the barrel due to the bullet's resistance through the rifling, there clearly is such a thrust. However, I do not consider this factor to be an important part of the the short recoil system for the following reasons:

1. The experiment conducted with the reamed barrel:

a) This barrel provided no resistance to the bullet due to rifling.

b) The gun functioned normally.

c) The bullet achieved 90% of the normal velocity.


2. The fact that a primed-only cartridge can propel a bullet partway through the barrel. Sure, the primer is powerful, but the amount of energy released is very minor compared to a full powder charge. Remember, the full powder charge represents the total amount of energy, it is much more than energy in a large pistol primer.

3. Niemi's experiment showed that 1250psi is required to move the bullet through the barrel. This is only about 6% of the 21,000 psi at work in the .45ACP.

Perhaps it is best that we simply agree to disagree?

[1911Tuner]

OK, let's look at Niemi's claim that it takes a maximum of 200lbs to move a bullet through the barrel.

First...It's not a "claim." He proved it to my satisfaction and everyone else's.


but in order to give you a break,

:D

I'll assume that it's total pounds and I'll convert to PSI.

He did that already. The reading was done in PSI.

However, I do not consider this factor to be an important part of the the short recoil system for the following reasons:

Think about what you're saying.

You know and admit that the bullet exerts a forward drag on the barrel. WE know that that forward drag is equal to the force that was required to get it started INTO the rifling because it's a direct 1:1 connection with no multiplying or reduction device.
Straight push. (If you apply X units of force on a wooden block...and that wooden block is bearing against a wall...you're imposing X units of force against the wall. No?

If the barrel is "feeling" 200 pounds of force in a forward direction, and the slide is pulling on the barrel...which it is...then the slide "feels" an equal/opposing force.

Again...Ned Christiansen showed that the recoil spring has very little effect on slide delay. You may assume that the mainspring/hammer assembly has even less, except at the very beginning of the slide's movement...which is where it does the most good. The recoil spring's effect is small at the outset of the event, and imposes the bulk of its will later...after the bullet is long gone.

Incidentally...the bullet drag/delaying effect is also imposed at the beginning of the event...where it does the most good...even though the drag/delay is in force for as long as the bullet is present and moving.

Thus, the recoil spring is more accurately described as an action spring, the primary purpose of which is in returning the slide/bolt to battery...and secondarily in opposing the slide's movement.

I'm starting to suspect that...rather than seeking understanding...you simply want to argue. That's fine. I enjoy a good debate as well as anyone...but this one has been up for debate many times, and I'm a little weary of trying to convince those who have their minds made up in advance, and won't allow anything factual or logical to interfere with that.

So...I'll suggest that you study Newton's 3 laws governing motion and the conservation of momentum...while bearing in mind that the 3rd Law applies in both directions...pushing and pulling...and that there is no physical way to have less force in one direction than in the opposite direction. Force forward is equal to force backward...pushing OR pulling.

Finally...an historical note on the fitting of barrels.

In the early days, before the slides and barrels were harder than what we use today...the practice of fitting and equalizing the lugs in the horizontal plane was accomplished by fitting the first lug wall, and leaving the forward pair with a small gap.
The target was .001-.002 inch. The equalizing was accomplished by firing the gun with two proof rounds to deform the first lug and allow the others to come into play.
This was known a "Recoil/Pressure Equalization" and it worked well. Still does, in fact, though a slightly different technique is required.

You don't get even soft steel to deform like that...even with proof-level pressures...unless there's a lot of opposing force on those lugs...or resistance, if you prefer. If that resistive force weren't pretty signifigant...pressure equalization couldn't occur.

In short, you believe what you believe...regardless of experimental data that shows otherwise. It's been written: "When the theory doesn't agree with the results of the experiment...go with the results."

So...Believe what you will. I've seen strong evidence to the contrary.

[Iron bottom]

Yep, JB probably would have used only one lug if he hadn't suspected something was going on with that barrel and bullet thing.

[1911Tuner]

JB probably would have used only one lug if he hadn't suspected something was going on with that barrel and bullet thing.


Bingo. One lug would've been much simpler in both the design and the execution.

I'm pretty sure that ol John Mose was well aware of it. ;)

Another bit of data that supports this is the good, old revolver and the stretching of topstraps that leads to excessive endshake and increased headspace. You can't stretch ordnance steel without having some pretty heavy opposing forces at work.

[berkbw]

I'm, from time to time, sorry that I have been a participant in this thread. But - what-EVER.

I think that gas operated pistols, tho a nice thought at 1st, in the end answer a question which nobody asked. They are designed to work when the gas system is fouled, which happens at each firing, and have to be over-engineered in unlock power to do so. Therefor the nasty experience in shooting one.

Pushing a bullet through a bbl by hand does not come close to live fire . One can not get the initial gas flow around the bullet, the short term memory after the round is compressed, and "stiction" vs. "friction.

I don't reload any more - it's been decades, but I have a couple of those super-cheap Sarco Roto bbls 1 is 18", so I might be able to vary powder amounts and such, searching for an answer. If someone here would like to do testing, I'd loan the bbls.

b-

[CO1911Carry]

After reading this thread, I am awed by the intelligence on display by the posters. All the more, I am astonished that John Moses was able to design and assemble such a magnificent symphony of metal parts in different shapes, hardnesses and angles, plus springs, in concert with immutable physical forces to produce his famous semi-automatic pistol. You call it science, but I'm unconvinced that it's not magic. I stand in awe.

[niemi24s]

FWIW, the core of a CCI BB JRN from the same box tested and mentioned in Post #56 tested BHN = 8.6. That figure is the average of four BHN's using four different sizes of indenter balls.

WIW? Probably the square root of zero point squat! :D

Cheers

[Greyswindir]

Amazing! :butthead:

Now you are the the one arguing Tuner! Because you have failed to agree with beckman's staggering powers of observation, prose, and physics!

I think I'm going to take a nice, long drive and forget about all the problems in this world, including, but not limited to, stubborn people who refuse to keep an open mind and argue (yet call it debating! :rolleyes: ) from a place of ignorance. Must be comfy in there! :dead_hors

Sunday morning coming down!

[beckman]

In short, you believe what you believe...regardless of experimental data that shows otherwise. It's been written: "When the theory doesn't agree with the results of the experiment...go with the results."

I find this to rather interesting, considering that you have never explained why YOUR OWN experiment with a reamed-barrel 1911 could possibly function "normally." If the delayed-blowback/forward-thrust effect was an integral part of the short-recoil system, your experimental 1911 should NEVER work because, according to your own comments, barrel resistance had been eliminated. You have never even bothered to squarely address this issue.

On the other hand, I have accepted yours and Niemi's data about the amount of pressure required to push a bullet through a barrel. I put this into context by comparing it with the total pressure in the .45ACP. You did not address the implications of this proportion.

When I mentioned that a primer, alone, is enough to propel a bullet partway through a barrel, you even admitted that a primer is very minor compared to a full-power round. Yet you then claim that I'm ignoring the effects of bullet restance in the barrel and I should study Newton.

I have provided three items to illustrate that compared to the TOTAL ENERGY, the bullet's resistance in the barrel is minimal. Sure, 200lbs means something, but it is minor compared to the rest of the equation. On the other hand, you've provided little experimental evidence to support your claim that forward thrust is important. Yes, Ned's experiment MIGHT show that forward thrust is important, but the force required to cock the hammer is still at work.


I'm starting to suspect that...rather than seeking understanding...you simply want to argue.

I asked that we agree do disagree. You don't even want to agree to that. Instead, you reply with a borderline insult, claiming that I only want to argue. I've tried to keep this conversation civil. I've acknowledged your expertise and knowledge, but you accuse my of doing nothing more than arguing. OK, I'll put that one to rest and I will not "argue" any further.

Remember, if Kuhnhausen could be wrong, so could any of us, including you.

[Hill]

Hmmm, sumptin' tells me that I'd better take the time to read this thread after all...

[niemi24s]

OK, let's look at Niemi's claim that it takes a maximum of 200lbs to move a bullet through the barrel. I'm not clear whether this is PSI or total pounds, but . . .
Each of those figures is the force in pounds (as you subsequently and correctly assumed) - not the pressure.

[niemi24s]

In Post #41, Beckman gives a synopsis (and a link to) Tuner's experiment with a smooth-bore, 50 calibre 1911 barrel in which the gun functioned normally.

While it may be convenient to imagine the bullet being propelled down this oversized barrel, cushioned all around by propellant gases blowing by between the bullet and bore and preventing contact and the resulting friction between the bullet and bore - is this what really happens?

Perhaps (instead of whizzing cleanly down the tube) the bullet yaws by about the 9° allowed by the geometry of the situation, makes contact with opposite sides of the bore, and goes down the bore yawing from side to side (or some other form of motion) - contacting the barrel either intermittently or continuosly until it exits the muzzle.

Maybe this "ricochetting down the barrel" is what allowed the gun to function (or contributed to how well it functioned) - maybe.:p

Regards

[Iron bottom]

Well, if bullet and barrel friction are nominal, ought to be easy enough to shoot a squib out of a barrel. Pushing a bullet through a barrel and firing one through it are most likely two different animals. When firing a bullet through there will be high pressure combined with heat and expansion of the bullet and barrel.

[1911Tuner]

Beckman...I really ain't tryin' to bust your chops, but so far your points are based on your belief. Belief and theory are fine, but until you back it all up with proof...or at least something more tangible than just theory...it's no more than theory.

We can believe that the moon is made of green cheese if we wish...but until somebody goes and cuts off a chunk...brings it back...subjects it to chemical analysis and shows conclusively that it is in fact made of green cheese...it's theory and no more than that.

So, go devise and perform an experiment that supports your belief and come try again.
If you can't or won't do that...then we really don't have any more to say than we've already said.

Sorry that you can't understand what my reamed barrel experiment showed. I've explained it three different ways, and I can't seem to find the right words to make you understand it.

Sorry that you can't accept that it takes about 10 times more force to start the bullet into the rifling than it takes to move the slide against all other resistive forces...and how that force requirement may actually be greater than under normal firing. See "Bullet Obturation" for an explanation of the plastic deformation that bullets undergo when subjected to high pressures applied over a millisecond or two.

Sorry that you can't grasp the fact that force forward equals force backward...pushing or pulling...and whatever resistive force is applied in one direction is applied in the opposite direction in equal measure. No room for much debate there. That's why the 3 dictums governing motion and the conservation of momentum aren't called "Newton's Theories of Motion."

So...your beliefs will remain just that. Your beliefs. At this point, I get the feeling that if the ghost of John Browning himself appeared and explained it...you wouldn't believe him either.

Cheers

[1911Tuner]

Whoops! Almost forgot...

I asked that we agree do disagree.

I never agreed to agree OR disagree...and that's not what you asked for. You asked me to explain the function in greater detail. I did that...or at least I tried...by offering phusical evidence. You're the one who started trying to disprove it with nothing except theory.

Incidentally...you keep referring to proportional forces. That has nothing to do with it. If it requires 100 ft pounds of force to move an object...it requires 100 foot pounds, regardless of how much is actually applied, or how quickly it's applied...unless you believe that because 10,000 foot pounds is used, or that the force is applied over a very short time frame...that the force requirement to move the object magically changes.

[twin oaks]

Geez, take a haitus, and look at all I've missed.
Tuner, thanks for bringing up this topic, it's been an exhilarting read. I'd like to throw my own bit of onion in the stew, too.
In the Tripp video, we saw conclusive evidence that the barrel begins movement before bullet exit ( at something like 4000 frames per second). Then it's movement slows, the bullet exits, and the slide completes recoil. That first umpteenth of a second and Nth of an inch movement when the slide slows is proof of the bullet's forward exertion of force on the barrel, keeping it locked to the slide. Once the bullet exits and the forward force is gone from the barrel (and since I'm way under qualified to calculate the frictional exertion of expanding expended gasses on the walls of the barrel as they move parallel to said barrel, in converse to any propusory effect in the opposite direction, I'll just leave those out; you'll need Niemi for that), the preserved energy of the slide pulls the barrel into link down. For naysayers, the preserved energy retained by the slide, until acted upon by forces such as the mainspring, through mechanical disadvantage of the FPS, action spring, impact of the lower lugs at the VIS, and the conversion of lateral energy to rotational energy through the tortion of the wrist (and of course the resistance to it) is the same as the energy that launches the bullet.

Mike

[1911Tuner]

Mike...To answer the question that you asked on the PM...

Yes. The gas and particulate ejectiva following the bullet does exert an "aftershock" recoil impetus on the breechface. It doesn't offer much in a pistol cartridge, though.

The expanding gas...even if the powder is completely consumed...has mass. That mass is equivalent to the mass of the unburned powder, or so nearly equivalent that the difference can be ignored for all but the most precise purposes.

In bottlenecked rifle catrtridges which powder capacity is close to or equal to the mass of the bullet...it can be signifigant...and "feelable." The rifle continues to push for a brief instant after bullet exit. The jet effect is enhanced by the venturi effect of the shoulder and neck. More velocity equates to more momentum (Mass X Velocity)

Because the momentum and energy established by the bullet's impulse...and the time frames involved...you won't be able to detect when one ends and the other begins.

In the .45 ACP...with the typical 5 grain powder charge at low operational pressures...it's not a signifigant push, and the already established recoil momentum will mask it. It's there...but you'll never be able to detect it. The actual numbers are...and this is a close estimate...5 grains mass X Mach 1. Or about 1/6th the recoil impetus that you'd get from a standard velocity .22 Short.

Jump to a .30-06 cartridge, with 50 grains of powder at close to Mach IV gas velocity, and the impetus is roughly equivalent to the impetus generated by a hot-loaded .220 Swift firing a 50-grain bullet.

Before bullet exit, the mass of the gasses are figured in...and thus a .45 caliber round's recoil is generated by 235 grains total. The gas velocity doesn't exceed the bullet's velocity until after the bullet exits...rifle or pistol.

[Iron bottom]

Just remembered something. I heard that the bullet, upon firing, was released, or maybe partially released, by the brass expanding from the pressure of the gas in our powder, primer, case and bullet packaging system. May be why brass is thinner at the case mouth and why we see that little puff of smoke before the bullet exits. Anyway, if there is anything to this idea, barrel and bullet friction would seem to play a larger role in delaying the slide. Any thoughts, Gentlemen?

[twin oaks]

Thanks, Tuner, I wasn't sure if that particular sub-topic was at place in this discussion, hence the PM.

[1911Tuner]

Just remembered something.

Gerald...Yes. It's a factor that plays into the whole, and can't be discounted...but not related directly to the resistance encountered upon entering the rifling. That event creates a "new" outside force, that...depending on the physical dimensions of the chamber and leade...can begin before the case releases its grip.

Guys...I've studied on this thread, and in an attempt to heal a few wounds...and quell some of the anger that's been inccurred...and in hopes of educating beckman..I'll try one more time by putting it in the simplest terms that I can come up with. He seems to be stuck on the question of proportional forces...or the disparity of force. The proportions and disparity of force is irrelevant.

Note that I will susbsitute "weight" for mass...in the interest of simplicity.

A 100-pound barbell is on the floor. If you exert 100 pounds of lifting force, the weight won't move because balanced forces create equilibrium.

If you exert 101 pounds of lifting force...the barbell will move off the floor. I will move slowly...but it'll move.

If you exert a 1,000 pounds of lifting force, it will move fast...but it still weighs 100 pounds, and it will still exert a resistive force of 100 pounds. This holds true if you exert a million or a billion or a trillion pounds of lifting force. The weight/mass of the barbell will remain constant. Only its rate of upward acceleration changes.

Because the conservation of momentum dictates that, as the weight mover faster, it requires less net force to keep it moving than it took to get it moving in the first place...BUT IT STILL WEIGHS A HUNDRED POUNDS, and it will still resist a change from a constant velocity with that same inertial resistance.

[Greyswindir]

Beck,

Would the their still be frictional forces at work on the barrel, even if the rifling was non-existent? Since the cartridge is in the barrel chamber there should still be substantial friction occurring, enough to drag the barrel forward and keep the system functioning as it normally does.

If anyone has been a little combative its been you and I. Don't let a little beef stop you from thinking all this stuff out. You did make a good point, every single one of us is capable of making mistakes, including Tuner. Though I still feel Tuner's argument or whatever you'd like to call it is correct and rooted in factual information and not theory or conjecture.

If I made some offensive comments towards you Then I apologize.

P.S.,

Obturation probably did have an effect on forward drag between bullet and barrel. Something to think about anyway. So the .50 cal experiment does not necessarily prove there was no contact with the barrel walls and the bullet. Bullet yaw is also a good possibility, obturation, depending on the alloy used, is pretty much a given.

[gans]

Maybe someone can help me understand the forward barrel force a bit better.

I seems to me that increasing the friction of the bullet in the barrel would increase the camber pressure. That in turn would increase the pressure rewards on the slide as well. Wouldn't the two opposing forces cancel each other out? If they did, then how would there be a delay in the slide travel?

[1911Tuner]

Wouldn't the two opposing forces cancel each other out?

Nope. If they cancelled each other out, you'd have equilibrium...and nothing is moving.
Force can't be cancelled out. Even if no motion exists...the force is still there.
So long as motion exists, you have unbalanced force...and outside forces that are working to restore balance and equilibrium. In order for equilibrium to exist, both the compelling forces and the resistive forces must be equal. If the outside/resistive forces can't equal compelling force...then the object will keep moving in the direction that it started, albeit at a slower pace.

[Hawkmoon]

Maybe someone can help me understand the forward barrel force a bit better.

I seems to me that increasing the friction of the bullet in the barrel would increase the camber pressure. That in turn would increase the pressure rewards on the slide as well. Wouldn't the two opposing forces cancel each other out? If they did, then how would there be a delay in the slide travel?
Force has a magnitude component. "Stuff" has a mass component. Force acts on and is resisted by mass. The combined mass of a slide and barrel (which is what a ballistic event is pushing backwards) greatly exceeds the mass of a bullet -- which is what the ballistic event is trying to push forward.

An increase in barrel friction, which would increase the pressure, would not cancel anything out because the higher pressure would still be acting in both directions -- pushing the bullet forward while pushing the slide/barrel backward.

Where it "cancels out" is the special case of a squib load, where the pressure drops below what's needed to overcome the friction and the bullet remains lodged in the barrel. But -- there have been instances in which squibs produced sufficient energy to cycle the slide, eject the spent case, and load another round. Those are the ones that create bulged barrels.

[1911Tuner]

Hawk...Outstanding explanation!

[gans]

I am referring to the INCREASE of forces being cancelled out.

I can see an increase in the forward force of the barrel that the bullet causes as the bore gets tighter as compared to a bored out barrel. It seems to me that a tighter bored barrel would increase the forward force on the barrel. It would also constrict the bullet more and cause higher chamber pressure. If you have higher chamber pressure, then there should be an increase of the rearward force on the slide. Would not the INCREASED forward pressure on the barrel be cancelled out by the INCREASED reward force on the slide to bring it into equilibrium?

If the barrel is locked into the slide, how can the forward force on the barrel slow the slide down? Yes you have the barrel being forced forwards, but you also have the pressure forcing the slide rewards. Any INCREASE in the barrel forward force should be equalized by an INCREASE force rewards to the slide. So how is the slide being delayed since the barrel and slide are locked together?

I can see how the forward force of the barrel will delay the slides movement, but only if the increased reward force on the slide is ignored. Where am I going wrong?

[1911Tuner]

I am referring to the INCREASE of forces being cancelled out.

Can't do it unless the resistive force EQUALS the compelling force.


Would not the INCREASED forward pressure on the barrel be cancelled out by the INCREASED reward force on the slide to bring it into equilibrium?

Nope. The proof is that the bullet moves and accelerates through the barrel. We're not dealing with a hard, mechanical blockage. We're dealing with a set coefficient of friction that eventually lets things slip.

If the barrel is locked into the slide, how can the forward force on the barrel slow the slide down?

Because whatever resists the barrel resists the slide...because the slide pulls the barrel backward.

Let this sink in:

Whatever frictional resistance that is imposed onto the bullet BY the barrel, is also imposed on the BARREL by the bullet. Cork on a rope in a pipe. Pull them apart.
You feel resistance in both directions. The pipe resists the cork...and the cork resists the pipe.

Newton 3 works in both directions...whether pushing or pulling. In this instance...pushing and pulling are in operation at the same time.

[1911Tuner]

I can see how the forward force of the barrel will delay the slides movement, but only if the increased reward force on the slide is ignored. Where am I going wrong?

Like Beckman, you're concentrating on the proportional force...and that's irrelevant.

Back to the barbell. It doesn't matter how much force that you apply...it still weighs the same as it did before the force was applied....even while you're lifting it. More force only means a faster rate of acceleration. Mass is constant, and so is the coefficient of friction.

[niemi24s]

FWIW (my last, I promise) it took about 270 pounds of force to slowly push a USGI 235gn JRN Ball bullet (Federal) with a 0.018 inch thick jacket down the same barrel used in previously reported tests. The barrel was clean and dry.

[1911Tuner]

FWIW (my last, I promise)

Don't make promises, Daniel my brother. You've got one more. I promise. :D

Do it again with the GI bullet...but this time...shove it through as fast as you can...and watch the needle jump way yonder past the slow reading.

[Iron bottom]

I'd be willing to bet very few mens or womens could hold a pistol with their strongest grip while standing in their most intimidating stance and let somebody or some machine jerk a bullet through the barrel without losing their grip or being pulled off balance. :D

[kcshooter]

I'd be willing to bet very few mens or womens could hold a pistol with their strongest grip while standing in their most intimidating stance and let somebody or some machine jerk a bullet through the barrel without losing their grip or being pulled off balance. I do it all the time.


(Of course, the machine is the 1911 itself, but that counts, right?)

[1911Tuner]

I'd be willing to bet very few mens or womens could hold a pistol with their strongest grip while standing in their most intimidating stance and let somebody or some machine jerk a bullet through the barrel without losing their grip or being pulled off balance.

Yeppers.

Let's take it a step further in the hypothesis, and imagine a pistol with a bullet stuck in the barrel...about halfway through the leade...so that it still has a bit of swagin' and engravin' left to do before it gets into the bore.

Lets hypothetically drill a hole through the bullet and insert a threaded rod...and put a washer and nut on the rod at the base of the bullet.

Let's lock the gun into a vise, and have a high-school wrestler pull forward on the rod as hard as his muscular little body will allow...while we try to hand-cycle the slide.

Any takers on the bet that you won't be movin' that slide until the bullet starts to slip?

Anybody wanna make an estimate of how much resistance you'd get when you pull on the slide as the bullet slips forward?

I can tell you precisely how much. The same level of resistance that the young lad on the rod will feel. Exactly. On a slow pull, Niemi's test results indicate that will be about 270 pounds AFTER the bullet gets though the leade.

Try lifting 270 pounds to get an idea of how much resistance the bullet imposes on the slide and barrel.

[gans]

I always like to look at things differently to try and learn more. As an example, I don't see 270 pounds as very much compared to 40,000PSI or more pushing back on the slide. Not to mention the chamber and locking lugs of the slide and barrel.

I have not noticed the bullet friction on the barrel slowing the slide down that much. Not that it even matters, since a rifled barrel is necessary anyway. Talk about adding weight to the barrel, changing the timing of the barrel lockup and varying the weight of the slide; now there is where we can see some real results.

It has been interesting reading everyones information on the great 1911 design.

[Greyswindir]

The result may seem small but is a vital part of the overall function of the system. Think of it in the terms of balance...a massive object balancing on the edge of a great abyss can be toppled into the abyss by a very small force acting upon it.

The barrel does slow it down, and enough so that if it wasn't present everything would be thrown out of balance. Remember, opposite and equal reactions.

[1911Tuner]

I always like to look at things differently to try and learn more. As an example, I don't see 270 pounds as very much compared to 40,000PSI or more pushing back on the slide.


You're still hung up on that proportional thing. It doesn't matter what the proportional difference is. The resistance is still the same...and the delay that results from it is the most signifigant of any of the outside forces that resist the slide...regardless of how much or how little that delay is in terms of proportion. And, with the .45 ACP, it's 20,000 psi...not 40,000.

Not to mention the chamber and locking lugs of the slide and barrel.

Has nothing to do with the delay, other than the fact that the lugs tie the barrel and slide together for a brief instant.

I have not noticed the bullet friction on the barrel slowing the slide down that much.

That's not surprising...seeing as how it all happens in a few milliseconds, and there are several sensory inputs going on at the same time. Your brain can't process it that fast. You can't tell the difference between the felt recoil that comes from the spring and that which comes from the slide impacting the frame, either...and that happens much slower than the internal ballistic event...even though the two are completely separate occurrences with two distinctly different impulses.

[Iron bottom]

We'll let that count, KC. My sister could probably hang onto it, but she bear hunts with a switch. :)

[log man]

I always like to look at things differently to try and learn more. As an example, I don't see 270 pounds as very much compared to 40,000PSI or more pushing back on the slide. Not to mention the chamber and locking lugs of the slide and barrel.

I have not noticed the bullet friction on the barrel slowing the slide down that much. Not that it even matters, since a rifled barrel is necessary anyway. Talk about adding weight to the barrel, changing the timing of the barrel lockup and varying the weight of the slide; now there is where we can see some real results.

It has been interesting reading everyones information on the great 1911 design.

The 270# noted is the static force required to push the bullet through the bore by hand. And that is all the bullet feels. However if you put a dynamic pressure of 40,000 PSI (whoa! that's HOT) against the breech face you are also putting 40,000PSI of pressure against the bullet base, which it feels for the period that it is in the barrel and that's why it doesn't hang around too long.

While it's in the barrel the bullet is subject to this pressure just as the breech and entire barrel and chamber are. And since the bullet is slipping in the bore the balance of pressure is upset, and explains the slides slight movement before the bullet exits, but remember the bullet is, while it's slipping still pulling on the barrel with this pressure of 40,000PSI.

The fact that the bullet takes 270#of force to push through the barrel demonstrates that it has resistance, and that is all that is required to hold the slide back from full recoil, while the bullet is still in the bore.

LOG

[kcshooter]

My sister could probably hang onto it, but she bear hunts with a switchSee, now that brings the sport back into hunting!

[1911Tuner]

while it's slipping still pulling on the barrel with this force of 40,000PSI.

20,000...and its force against the barrel is limited by its coefficient of friction. Not sure what the net coefficient is with ordnance steel and cupro-nickel...but ordnance steel alone offers .16 coeffiecient with another piece of ordnance steel.
So...20,000 X .16 is 3200 X the surface area of the bullet base. 3200 x .203 comes to about 650 pounds. That leads me to think that I've left something out because that seems to be too high...but that force applied over the span of 3-4 milliseconds with nearly 4500 pounds of net force against the slide...it may be pretty close.

Hmmmm

Anybody got any other numbers to plug in?

[log man]

Yes, of course 20,000psi is still at the high end but just using gans numbers.The point I was making is the full force is on the bullet base while it's in the barrel and has resistance( sealed in the bore).

I'm thinking of an example of a truck on a hydraulic jack. Let's say too keep with gans numbers that the 20 ton jack is holding up one end of an 80,000# truck. So the jack has 40,000# on it, when you crack the valve to let it down slowly(the resistance) and it's coming down the 40,000# is pushing down on the jack head the entire time.


LOG

[1911Tuner]

Log...Yup.

Let me restate...again...that I never claimed that the bullet-induced slide delay is a huge factor. I said...and I stand by it because of physical evidence that supports it...that the bullet was the single most signifigant factor of all the delaying forces. Namely...The recoil spring...Slide to frame rail friction...Slide inertial mass...The barrel's mass...The hammer's mass...and the mainspring.
You may add wind resistance if you wish, but that's splittin' hairs one too many times.

Why do I say this? Because you can hand-cycle the slide as fast or nearly as fast as it moves when the gun fires. This one is easily demonstrated.

Moreover...Ned Christiansen's timing experiment/demo showed that it has a greater delaying effect than all the other factors combined.

Remember...The delay doesn't have to last long. It only needs to last long enough for the bullet to clear the muzzle and allow pressures to drop so the breech can open safely. Any added delaying force serves to give the bullet another millisecond or two to reach the muzzle.

[log man]

I don't see the coefficient of friction as important as the fact that the bullet is sealing in the bore and therefore feeling the full pressure of the charge. As long as there is resistance. And the indisputable fact that a period of time elapses while the bullet travels from chamber to muzzle. The coefficient of friction will have an effect on the amount of pressure developed. As a 230gr. bullet will generate more pressure than a 200gr. bullet with the same charge. But the greater pressure will be felt by all, and won't change the delaying of the slide to full recoil. As long as the bullet is in the bore, the slides movement will be restrained to the .100" of movement.

Just as in my analogy, post#2, Mr.Breech and Mr. Bullet could be wimps or bodybuilders the result would be the same.

And I'm standing right behind you on this (don't worry it's safe)I'm just trying to re-state in different ways to spark understanding.

LOG

[1911Tuner]

I don't see the coefficient of friction as important as the fact that the bullet is sealing in the bore and therefore feeling the full pressure of the charge.

Because the coefficient of friction and the bullet's inertial mass ultimately determine how much force is required to set it into motion. Once it's in motion, the force requirement drops due to Newton's law governing the conservation of momentum.

Like a car moving at a constant velocity of 60 mph. You can maintain that speed with a light touch on the gas pedal. But if you accelerate it from 0 to 60 as quickly as possible...the force requirement is much higher.

If you hypothetically developed a miracle alloy that was friction free...no matter what the other surface offered, and no matter how much vertical loading was placed on it...then the bullet wouldn't delay the slide at all, and the force required to accelerate it from a standing start to 800+ fps in 4.1 inches of barrel would only be determined by the bullet's inertial mass.

In Niemi's experiment...instead of 270 pounds of force to push it through...it would require almost none.

Note that a steel plate with .16 coefficient of friction has a much different acceleration force requirement when that friction is multiplied by its own weight and mass...and when there's an additional hundred-pound weight placed on it...even though the coefficient remains the same. The force requirement varies with vertical loading.

The squeeze imposed by the bore and the rifling lands places a vertical load on the bullet...that is...90 degrees to its axis and direction of travel. Thus, a badly worn bore will offer less frictional resistance to the bullet's entry...but the coefficient of friction will be constant.

[log man]

I don't see the coefficient of friction as important as the fact that the bullet is sealing in the bore and therefore feeling the full pressure of the charge. As long as there is resistance.
LOG

The point being that as long as there is resistance there is a coefficient of friction, but that coefficient of friction can vary from bullet type and bullet weight without changing the mechanics of the cycle, and the delaying of the slide.

LOG

[1911Tuner]

The point being that as long as there is resistance there is a coefficient of friction


Kinda backward, Log. As long as friction exists...regardless of the precise coefficient figures...there will be a resistance.

but that coefficient of friction can vary from bullet type and bullet weight without changing the mechanics of the cycle, and the delaying of the slide.

If one thing changes...it changes other things. If the coefficient of the bullet material goes up or down...so goes the net resistance offered by that change. The reason that the variation doesn't alter the function of the gun is because as goes the resistance...so goes the force requirement also...and since force forward equals force backward...if the net force on the bullet is lower, the net force on the slide is lower. The slide doesn't accelerate as quickly, so the delay is proportionally in sync.

Also...have you noticed that a given powder charge will produce higher velocities with cast lead bullets than with jacketed bullets of identical mass? It's a fact. So, not only does the lower resistance induce less force requirement...the bullet gets out earlier relative to the slide's position for a given force imposed.

[niemi24s]

Anybody got any other numbers to plug in?

• The net force required to uniformly accelerate the mass of a 235gn bullet from zero to 835fps in 4.41 inches = 989lb (average).
• Assuming the 270lbs of frictional resistance when moved slowly is the same when fired, the force on the base of the bullet to accelerate it down the barrel must then be 989 + 270 = 1259lbs (average).
• The pressure on the 0.1541 0.1578 square inch bullet base (once in the rifling) to create this 1259lb force is 6118 7,978psi.
• In order for the bullet to go from zero to 835fps in a distance of 4.41 inches, it must be accelerated at an average of 1,207,095ft/sec/sec (or 37,487 g's)
• The amount of time it takes the bullet to just be clear of the muzzle is 692µsec (0.692msec or 0.000692sec)
• In this same amount of time, the mass of the 17¾oz slide, barrel and bushing will move aft under the same average force of 1259lbs and the distance moved aft will be 0.098 inch - at which time the bullet will have just departed the muzzle. [Edited: unless the net aft force on the slide, etc, is only 989lbs, in which case the aft movement will be 0.077 inch]

Several things assumed and several things ignored, but that's the only way I could do the figuring.

[Hawkmoon]

The 270# noted is the static pressure required to push the bullet through the bore by hand. And that is all the bullet feels. However if you put a dynamic force of 40,000 PSI (whoa! that's HOT) against the breech face you are also putting 40,000PSI of force against the bullet base, which it feels for the period that it is in the barrel and that's why it doesn't hang around too long.
Whoa!

I was going to let that 270# thing slide, but now you're messing up all the units so I have to clarify.

In fact, you have the terminology exactly reversed. The 270 pounds is not a pressure, it is a force. "Pressure" is force acting on area, as in PSI (pounds-per-inch-squared). Which means that the 40,000 (or 20,000) psi is not a "force" but a "pressure." How much work any given pressure can do is incalculable until you know how large a surface it is acting upon. In the instance of a .45 ACP bullet, if we assume a bullet diameter of 0.451 inches, the base of the bullet has an area of 0.1597 square inches. If the chamber pressure is 20,000 psi, the amount of force exerted on the bullet at maximum pressure is 20,000 x 0.1597 = 3,194 pounds.

Keep the terms consistent or this discussion is going nowhere except where that proverbial handbasket is headed.

[niemi24s]

Do it again with the GI bullet...but this time...shove it through as fast as you can...and watch the needle jump way yonder past the slow reading.

Sorry, no can do. My scale was already within about 5 or 10 pounds of being maxed out when taking some of the slow readings to get the average.

Would probably need a scale with at least a 500lb capacity - and a peak recording/indicating feature to do this.

Cheers

[log man]

Kinda backward, Log. As long as friction exists...regardless of the precise coefficient figures...there will be a resistance.

Well, I kinda thought that's what I said, in the context of a bullet in a barrel you can't have one without the other, if, you have friction between the bullet and barrel, you have resistance, and there exists a corresponding coefficient of friction, which can vary from bullet to bullet and barrel to barrel. And the beauty is it still works the same. :)

Yes, I certainly have noticed that a given bullet in plated, jacketed, or moly coated of the same weight and charge have different velocities.

We, are maybe using different words, but I don't see a difference of meaning on this topic.

LOG

[1911Tuner]

The net force required to uniformly accelerate the mass of a 235gn bullet from zero to 835fps in 4.41 inches........

Dayumm! Niemi...you is good! Hmmm. Makes me think that maybe my figures weren't that far off after all.

On the other hand...Assuming that the net force on the bullet's base is constant isn't gonna hold true as the bullet accelerates to higher velocity. As the velocity increases, the conserved momentum dictates that the force requirement will drop. How you're gonna plug that one in is gonna be interestin' to say the least. :D

Hawk...When I figured the base area...I plumb fergot to use Pi.
Dagnab this gettin' in a rush! :rolleyes:

[Greyswindir]

I'm curious guys,

Will a bullet obturate if it is excessively smaller than the bore it is shot from...even if the alloy is harder than normal or if the copper/bronze jacket is thicker than normal? I'm also talking average 1911 pressure here, not 38 Super.

Thanks.

[niemi24s]

As the velocity increases, the conserved momentum dictates that the force requirement will drop. How you're gonna plug that one in is gonna be interestin' to say the least.
Got no idea how to plug that in, so was forced to base everything on averages - as if the force on the bullet was constant from start to finish. Have forgotten all of what little I ever new about stuff like integral and differential calculus - except how to spell them! :D

When I figured the base area...I plumb fergot to use Pi.


Pi R square? NO! Pie R round!!

FWIW, my figure of 0.1541 0.1578 square inch for the bullet base is simply the midspec value of the cross-sectional area of the hole down the middle of the barrel - the bore area plus the area of the 6 spaces between the lands (from bore to groove diameter). I then assumed the bullet filled this area completely.

[I calculate nit-noy stuff like that just to keep my little grey cells from atrophying - too much, anyway. :)]

Cheers

[log man]

HAWKMOON,Thanks for the clarification, I cleaned up my mess.

I believe, PSI stands for Pounds per Square Inch not Pounds per Square Inch Squared. Or were you thinking PSIG Pounds per Square Inch Gauge, in regards to chamber pressure I've only seen CUP and more lately PSI.

LOG

[1911Tuner]

Will a bullet obturate if it is excessively smaller than the bore it is shot from...even if the alloy is harder than normal or if the copper/bronze jacket is thicker than normal? I'm also talking average 1911 pressure here, not 38 Super.

If it encounters a resistance at the front with overwhelming force from behind...it would have to. How much...and whether it would seal the bore depends on how much too small and how hard the metal is.

Niemi...I took one look at calculus and decided that I'd rather eat worms...

:lh:

[niemi24s]

I took one look at calculus and decided that I'd rather eat worms...
Thinking back on it, I probably should have done the same thing! :D

Cheers

[niemi24s]

. . . Pounds per Square Inch Squared.
That'd work out to "square pounds per four-dimensional space"!!

Now, that's something a fella could really sink his teeth into!!!:lm:

[1911Tuner]

Now, that's something a fella could really sink his teeth into!!!

You and emilio jump on it! I'll go put the coffee on and wait...

[1911Tuner]

Since we've hit a short lull in the action...I thought I'd take the opportunity to toss out a couple other physical facts that a lotta folks have trouble with.

Air has mass. Yep...and I ain't talkin' smoggy/smoky air...which has more mass than clean air. Air has mass.

If you scribe a circle around the base of the Eiffel Tower, and construct a cylinder of that diameter that encloses the tower...and only take into account the mass of the air contained in the cylinder...The air in the cylinder will weigh more than the tower itself. True.

If you go into the weightless vacuum of outer space and throw a ball, the ball will continue to travel at the speed that you threw it until it either hits something, or encounters the gravitational field of another body. True.

Weight and mass are related only when under the effect of a gravitational field. In outer space, the Empire State Building and a baseball weigh exactly the same. Nothing. BUT...You can easily throw a baseball in outer space. You can't do that to the building.
Hence the difference between weight and mass.

Einstein's Theory of Relativity is nothing more than a theory...and although widely accepted for decades...has yet to be proven, largely because it's impossible to disprove with the technology that we have available. As this is written, there are literally hundreds of very sharp people who are feverishly working to disprove it...but they haven't been successful to date.

[Swampfox]

Tuner - Don't you think we need a pop quiz on posts 1-117 before you start covering new material?

[1911Tuner]

Tuner - Don't you think we need a pop quiz on posts 1-117 before you start covering new material?

Nah. Except for a couple impenetrable belief systems...I think things have been cleared up. I thought I'd start another fight. :D

[CO1911Carry]

Tuner introduced some things during the lull in the thread's action and mentioned the concept of weight and mass.

I didn't understand it in high school about weight and mass. As I remember, weight is only relevant in measuring an object's relationship to earth's gravity. I got lost with the mass concept. Aren't all measurements only valid in describing relationships? If so, what does mass relate to?

I hope these questions are appropriate here.

[1911Tuner]

what does mass relate to?

The amount of stuff that's in it.

Weight requires gravity to mean anything. A car and a feather weight the same in the absence of gravity. The mass remains constant.

[CO1911Carry]

Mass, then, is density?

[Swampfox]

If you scribe a circle around the base of the Eiffel Tower, and construct a cylinder of that diameter that encloses the tower...and only take into account the mass of the air contained in the cylinder...The air in the cylinder will weigh more than the tower itself. True.


While this may be true at the elevation of Paris, I believe one would have to do some cyphering to see if this were true on top of Mt. Everest?

[berkbw]

Mass, then, is density?
Density is mass (or pounds depending on units) divided by volume.
Same stuff taking up less volume has greater density.

[1911Tuner]

Berk beat me to it. It's kinda/sorta...in a roundabout way...but not exactoy. Density is the ratio of mass to volume. Or...mathematically...Mass divided by Volume. A hot air baloon has volume, but not much mass, because it's mostly air. It's "massive" but doesn't have a lot of mass, if that makes sense. If the baloon were filled with water, the vulume would be the same...but it would have more mass. Fill it with wet sand, and it would have more.

[CO1911Carry]

How about this? Can you say that an object initially is defined as having weight? When related to other aspects of physical existence and expressed in mathematical terms, its relationships are mathematically stable. When 'g', gravitational force, is removed from the object's definition, the object's mathematically defined relationship with the other aspects still stand as true. Mass divided by volume equals density no matter where in the Universe you are. On Earth, substituting weight for mass, the equation is still equally valid, right? Using this logic, albeit very poorly described above, one can say that the the one kilogram of flour on Earth will weigh but 600 grams on the Moon, but it will still have the same mass. Am I even close?

[niemi24s]

. . the concept of weight and mass.
Mass is nothing more than the amount of material (matter or stuff) in something. As long as the thing remains physically unchanged, its mass remains the same no matter where it is - here on Earth or out in deep space.

This thing (say, your bowling ball) has weight only when acted upon by gravity.

The relationship between mass (m), weight (w) and gravity (g) is w = m x g.

Here on Earth your bowling ball will weigh, say, 16lbs because when you place it on the bathroom scale gravity will pull the mass of the ball down onto the scale with a force of 16 pounds. The springs inside the scale are compressed by this force, and the scale's dial will indicate this force of 16 pounds. We refer to this 16 pounds of force as the balls weight.

The bath scale does not measure the mass of the ball. It only senses and indicates the force which gravity causes the ball's mass to exert on the scale.

The easiest way to find the mass of the ball is not to measure it, but calculate it from the above formula solved for mass, or m = w ÷ g, in which g is the acceleration any mass undergoes when dropped and acted upon only by gravity. Here on the surface of the Earth, a "close enough" value for g (in English units) is 32.2 feet per second per second (or 32.2ft/s/s).

The mass of the ball is m, and m = 16 ÷ 32.2 = 0.497lbm, the little m to differentiate weight and mass.

Out in deep space where there is little or no gravity (g = 0), when the same ball with a mass of 0.497lbm is placed on the scale, the scale will read 0lb because w = m x g = 0.497 x 0 = 0. In your hand, you need exert no effort to hold the ball stationary out in front of you because it is truly weightless.

If, however, you try to throw the ball across the spaceship, it does take effort because to throw it you must accelerate it and what you're accelerating is its mass - not its weight. And the force (in pounds) you need to exert on the ball to accelerate is found from F = m x a.

That's enough of that stuff! :p

[CO1911Carry]

The relationship between mass (m), weight (w) and gravity (g) is w = m x g.

With this equation and the definition of its terms, I finally understand. Thank you. :appld: I wish my physics teacher had been as clear. Of course, maybe he was and it was just me.

[1911Tuner]

but 600 grams on the Moon, but it will still have the same mass. Am I even close?


Yes. Mass is constant...no matter where it is.

[niemi24s]

Another less mathy way of thinking of mass is:

Stuff has mass because each of the atoms or molecules (bunches of atoms) that make up all of the different kinds of stuff in the known Universe has a mass of its own.

Atoms (and the molecules they can form when bonded together) have mass because each of the protons, neutrons and electrons that make up all the different kinds of atoms has a mass of its own.

And all that stuff has mass whether there's any gravity or not.

A hydrogen atom out in deep space half-way to the first star you see in tonight's sky has precisely the same mass as the hydrogen atom in one of the water molecules in the tears you'll wipe from your eyes after reading all this malarkey! :)

[1911Tuner]

Very good, Dan! Outstanding! Been so long since I took HS physics that the formulae are a bit...hazy. :)

Now then...Just to see who's been payin' attention...Shall we discuss why Johnny's Autopistol kicks? :D

Hint: It ain't from the action/reacion of the cartridge goin' bang...at least not directly.

[AmericasFirstFreedom]

Oooooh, oooooh . . . I'll try.

The "kick" comes from the slide impacting the frame. The linear velocity is translated to rotational velocity because the wrist is a hinge joint and causes it to "rotate" upward. Depending on the strength of the arm and associated muscles, that can also cause the upward rotation at the elbow and shoulder joints.

Am I in the ballpark, Professor Tuner?

[1911Tuner]

The "kick" comes from the slide impacting the frame.

Pretty close. The impact produces the greatest part of what we know as "Muzzle Flip" but is secondary to the primary cause of felt recoil. Well...Actually, tertiary...but the firing of the round produces so small a disturbance that it can practically be ignored.

[Greyswindir]

Then it has to come from the pressures having almost nowhere to go, right?...All of that energy has to dissipate, it has to go somewhere...since the system is sealed (somewhat) the force acts upon the mechanism in place designed to take advantage of the energy. And that would be the bullet leaving the bore, the opposite energy causing recoil, or blow back, etc. Then locking, blah, blah, blah, and so forth.

What are we missing here?

[1911Tuner]

Then locking, blah, blah, blah

Not nearly that complicated.


t are we missing here?

That big ol' draft horse standin' smack in the middle of the Zebra herd...

;)

[Greyswindir]

Gee, thanks for the hint Tuner!

Okay...wheels are turning, gears and cogs clanking, thumpty thump, ka chunk!

Still though, no little piece of paper has exited my big mouth with the answers written upon it!

I'm all outta carrots to boot!

[Greyswindir]

Maybe I'm/we're trying to answer the wrong question Tuner?

Could you rephrase the original question please?

P.S.,

Did you notice our post counters seem to be stuck on the same number?

[1911Tuner]

Could you rephrase the original question please?

Wht causes Johnny's autoloader to kick?

What generates most of the felt recoil when you fire an autoloading pistol? The slide hitting the frame's impact abutment provides the quick snap that we know as muzzle flip. What causes the other part...the "push" if you prefer?

[Greyswindir]

Ah ha!

I was trying to answer the wrong question, or rather answer it in more subtle terms. Sorry 'bout that!

Answer coming....hopefully.


The twist of the rifling effects the felt recoil...

[Greyswindir]

The twist of the rifling effects the felt recoil...but other than the impact from the frame abutment....what is the other cause...

Actually, we cause some of the push by trying to "control" the recoil. Am I getting close? I'm trying to think outside of the box but I don't know if it's working Tuner!

[1911Tuner]

The twist of the rifling effects the felt recoil

That's torque. While it's a part of the whole, it's not what actually puts the "kick" in recoil.

Looks like you're the only player, Grey. Give up?

The slide compresses the recoil spring...which in turn pushes on the frame. The recoil system is a separate closed system that begins its action and reaction the instant that the slide starts to move. The spring provides the force vector between the slide and frame...and whatever magnitude of force is applied to the slide is applied to the frame.

It's also depeneent on the slide's velocity. The faster it moves, the faster it compresses the spring...and the faster the spring applies force against the frame.

Hypothetically...if the recoil spring's resistance is increased until the slide won't move at all...the autopistol's recoil characteristics mimic the revolver's...and all the punch comes from the internal ballistic event.

To help understand it...Keep in mind that the slide assembly is the actual gun. The frame is a gun mount and a housing for the lockwork and magazine, and nothing more.

[CO1911Carry]

Tuner, this part of the thread deals with different components that make up the total of the felt recoil impulse. What would you say are roughly the percentages of each component? (When the percentage gets small enough, they can be lumped together as "Other" or "Miscellaneous.")

How succesful are the various attempts at recoil mitigation? I read about Shok-Buff pads, square-bottomed firing pin stops, changing the recoil spring strengths (even variable-rate springs), adding weight to the muzzle (a la NHC's Predator or Les Baer's Prowler III), adding weight to the dust cover (a la Les Baer's Monolith and Monolith Heavyweight), using a heavy FLGR and wonder how effective they are really.

[Greyswindir]

Nope, I never give up but looks like you let the cat out of the bag Tuner.

So it's the action spring then?

[1911Tuner]

So it's the action spring then?

Yup.
How succesful are the various attempts at recoil mitigation? I read about Shok-Buff pads, square-bottomed firing pin stops, changing the recoil spring strengths (even variable-rate springs), adding weight to the muzzle (a la NHC's Predator or Les Baer's Prowler III), adding weight to the dust cover (a la Les Baer's Monolith and Monolith Heavyweight), using a heavy FLGR and wonder how effective they are really.

The shock buffs reduce steel on steel impact, but I can't see how they'd reduce muzzle flip when the slide hits the impact abutment. It's still a question of momentum.
Mass X Velocity is unchanged. It may be a little less sharp, but I think you'd have to have a more precise measuring device than your hand.

The square firing pin stop works by reducing the mechanical advantage of the slide in cocking the hammer. By imposing a sort of "speed bump" at the very beginning of the slide's cycle...when the recoil forces are at or near peak...and delaying it until the bullet has moved and the pressure/force impulse is on a downhill run...the slide is moving slower once it gets past cocking the hammer.

If the slide is moving slower at any given point in its travel...the spring is compressing more slowly. Going back to Newton 1A and understanding that the faster you try to accelerate a resistive object, the harder it resists, and vice-versa...it results in a less sharp impulse backward. And...the effect is twofold. The slide is moving slower at a given point, and the rapid drop in pressure/force means that it can't regain that lost speed and momentum.

Adding mass to the gun also dampens recoil. A 6-pound .308 rifle will kick harder than a 9-pound .308 rifle with the same ammo. Same principle. Adding mass at the front of the gun helps to offset the muzzle flip when the slide smacks the frame...but does little to moderate the spring's effect, except by the added mass alone...and 2-3 ounces, or whatever they weigh...isn't going to have that much of an effect except on muzzle flip. If the pistol weighs 40 ounces, and the rod weighs 4 ounces...the theoretical effect is 10%. Feelable...but probably no more than reducing the powder charge by 10%.


Upping the recoil spring's rated load increases its equal/opposite effect...and vice-versa. It reduces the impact-induced flip, but the overall effect is changed little. You take your choice. More felt recoil for less flip...or more flip for less felt recoil.

Compensators work by using the jet effect of the escaping gas behind the bullet...directed upward. Since the majority of muzzle flip occurs long after the bullet is gone, it can't have any effect except by actually forcing the muzzle down before it then gets flipped up...giving the impression that it's actually combating muzzle flip.

They do just what their name suggests. They compensate...or actually they overcompensate. If the uncompensated muzzle rises 3 inches, and adding a comp comp depresses the muzzle 2 inches before impact...the net rise is one inch. That's representative, and not exact, by the way. The same can be said of porting. The bullet is gone and the jet effect over before the slide hits the frame. If the porting is angled backward, it combats the spring's effect by pulling the gun forward. The problem is that if the angle is too acute, the shooter gets a faceful of hot gasses...so there are limitations on the geometry with a pistol.

And...of course...compensators add weight and mass to the gun at the muzzle.

[Greyswindir]

Good post Tuner. You covered just about everything very succinctly.

[niemi24s]

Anybody curious, bored or anal retentive enough (like me) to see how much force it takes to shove one of their bullets down one of their barrels should make sure the shoving method doesn't distort (enlarge the OD of) the bullet base.

The method used in this thread involved the use of a 3/16" pin punch through a drilled-through primer pocket to push the bullet out of the case and into the barrel. The punch tip sank quite a bit into the lead core of the first JRN tested (see left hand bullet in pic below) and probably expanded the base a bit, giving a higher-than-normal force reading.

This problem was solved with the Bullet Push Adapter which distributes the pressure from the punch over a much wider area of the bullet base. It's placed in the case prior to seating the bullet, and is made long enough so it can't flip over inside the case.

http://i129.photobucket.com/albums/p232/niemi24s/P085280004aTXT.jpg
While a good sturdy drill press would simplify the process of pushing, here's a doodle of what was used:

http://i129.photobucket.com/albums/p232/niemi24s/P085290004e.jpg
The metal plate between the drill press vise and scale keeps the barrel (lightly clamped) from slipping down into the top surface of the scale.

[Greyswindir]

Wow neimi!

You've got lots of time on your hands, don't you? :D

I'm curious, why use a case at all? Why not just use a wooden dowel to drive the bullet through the barrel? I figure you use the case to keep things as close as possible to regular conditions...the bullet is crimped into the case I suspect?

Pretty cool experiment. I have a couple of your old drawings in my "diagrams" folder...one being a drawing of the breech blocks. I notice you use the same colored pencils everytime, same colors. Is there a reason for this or do you just like primary colors?

[niemi24s]

I'm curious, why use a case at all? ... I figure you use the case to keep things as close as possible to regular conditions...
Correct - for better bullet alignment.
...the bullet is crimped into the case I suspect?
No crimp applied. Minimum flare for seating bullet and the little remaining flare helps the case center the bullet better.
I notice you use the same colored pencils everytime, same colors. Is there a reason for this . . .?
No rhyme or reason in color choice. I just feel colors - any colors - make the drawings a little easier to comprehend. They do for me, at least.

[Greyswindir]

Thanks Neimi,

I always appreciate your posts, very informative.