EGW Modded FPS: What is the "perfect" radius?

[SBC Zilla]

I read through the 3billion page sticky, and searched every thread concerning this mod.
I cant get a good concenus on what radius to use.

My father is a machine shop owner and a very experienced old school tool and die maker.
Goes without saying, he will be doing this for me.

The original article states a 1/16th radius, or to be matched up with the same drill bit.
However, that was 2006. Since then, it seems I am seeing all kinds of different opinions as to the "perfect" radius.

Is it really that dire? Or should I just have him do it to 1/16th and be done with it?

He is going to go the extra mile and do it on a surface grilder that we have in our shop, just to ensure that its the same, from one side to the other.
Ill post pics of this as he is doing it.

[Jim Watson]

I'd go to 1/16" and not worry about it. Or even 3/32", it is not critical, the guns aren't total failures with the current large radius.

I have one with the edge broken just enough to not gouge the hammer face and it is not enough. Makes it hard to rack the slide and does not much affect the "feel" of the gun in operation. I will radius it to somewhere in the above range and get easier operation.

[log man]

There is a perfect radius and it is the one that works for you.The idea of using a radius less than the 7/32" radius current configuration is to change the way the recoil is controlled and felt. It is an aid in tuning, by reducing the recoil with a sharper radius a lighter recoil spring can be used and that helps to control muzzle dip when slide slams into battery. As suggested start with a small radius and work up.

Clarification,a 1/16" drill bit has a 1/32" radius, and that's an okay place to start.

LOG

[niemi24s]

Although I've never tried it, I have a sneaky feeling even a 1/16" X 45° chamfer would also work just as well. The larger and current US Army radius of 7/32" isn't tangent to either of the surfaces anyway.

[1911Tuner]

I have a sneaky feeling even a 1/16" X 45° chamfer would also work just as well.

It will. Some guys don't even break the corner, and use'em as they come. It doesn't seem to hurt blanked, machined barstock hammers. Cast or MIM hammers may be a different story, but if they're good castings...it'll probably take a long time to show it.

There isn't a "perfect" radius. The square bottom corner lets you tune it to your tastes. The smaller the radius, the greater the effect.

[niemi24s]

I wonder who'll be the first to say an elliptical countour is so-o-o-o much better than either a circle or a straight chamfer?:lm:

Cheers

[log man]

I wonder who'll be the first to say an elliptical countour is so-o-o-o much better than either a circle or a straight chamfer?

Cheers

If I'm not mistaken you just did! :confused: :D

Be careful what you say others only read half of the text.

LOG

[grendelbane]

I prefer a free form radius. Anything that can be described in simple terms is going to be inefficient compared to my extremely complex efforts!

[log man]

Well, yes, of course, I prefer the much bragged about, and very superior, not to be bettered, "parabolic cut"! :p

LOG

[berkeleygiraffe]

pretty sure EGW will sell you one with a small radius already in it? Or at least that's what I just purchased a couple days ago. The person on the phone said 1/16 radius I asked if that was the small radius and he said yep.

[1911Tuner]

1/16th is good. .060 is just as good. so is .055 or .065 inch. Not important that it be exactly a 16th. Neither you nor the gun will know the difference...even if it's a bevel instead of a radius...and it's much easier to do.

Even the uncut square corner has a radius. It's just a very small radius.

[Greyswindir]

Don't get too technical on us now tuner!

[Hill]

1/16th is good. .060 is just as good. so is .055 or .065 inch. Not important that it be exactly a 16th. Neither you nor the gun will know the difference...even if it's a bevel instead of a radius...and it's much easier to do.

Even the uncut square corner has a radius. It's just a very small radius.

Oh, I don't know about that one - seems to me that for someone with little file time cutting a clean bevel could be more difficult than making a rounded corner.

Seems like I remember plenty of times when I wanted a flat but got a curve. :)

3/32" feels best to me in 5" guns.

[1911Tuner]

seems to me that for someone with little file time cutting a clean bevel could be more difficult than making a rounded corner.


It might be if ya do it backwards. When most people think "file" they think about clamping the part in a vise and using the file in hand. If ya lay the file down on a flat surface...orient the corner to about 45 degrees...and drag it sideways on the file slowly and carefully...it's a snap. Remember too...that if you need to make repeated cuts...to bring it to a stop...lift the part straight up...a re-lay it on the file.

Whenever I use a file to cut a bevel...whether or not I intend to leave it as a bevel or finish it with a radius...I always cut across the corner rather than perpendicularly to it.
One or two licks...and there it is! ;)

[Jerry Keefer]

I have a sneaky feeling even a 1/16" X 45° chamfer would also work just as well.

Neimi;
This 1/16 X 45 degree angle is what I have used for quite some time..... I do it in the surface grinder as the other poster suggested so it's precise(square / parallel).
Now, I also grind a 2 degree slope on the face of the stop, and the hammer face, which allows the hammer to rest noticably forward of its normal in battery position, making for even more delay (resistance). A final angle is then ground on the bottom of the stop, to provide an escape angle for slide movement. Bullseye 1911s greatly benefit from these modifications. For the poster who finds his gun {too} hard to function by hand, merely cock the hammer first...the benfits far out weigh the extra effort.
I am assigned over 800 .357Sig service weapons to attend too. The radius on these guns and many other models I have inspected, are as small .060. No ill effects befall this design.

Jerry

[Greyswindir]

Right on Tuner,

that is exactly how I put my angle on my OS FPS's. It's a piece of cake that way. I don't bother with trying to round the angle as a little shooting will do the job...burnishing by fire!

[Hill]

I just cut one for my GCT using my tool & cutter grinder now to put a triple face on the corner of 30-45-60 degrees within a .065" radius.

[1911Tuner]

I just cut one for my GCT using my tool & cutter grinder now to put a triple face on the corner of 30-45-60 degrees within a .065" radius.


Wow. Not raggin' atcha, dog...but is there a specific reason for all that?

[Jim Watson]

Do you reckon he is doing it that way because he CAN with the machine he has?

Jerry, I have been thumb cocking the gun with teeny radius but it is kind of an unnatural act, being long experienced with long radius guns.

[1911Tuner]

Do you reckon he is doing it that way because he CAN with the machine he has?

Nah. Jerry works very carefully and precisely, and imposes tolerance limits on himself that are more closely related to toolmaking than pistolsmithing. If Bullseye competitors are cut from a different bolt of cloth, the smiths who build their guns for'em tend to split hairs 3 and 4 times in the effort to gain just a tiny edge. Jerry is one of those who will split that hair 10 times. That's why there's such a long waiting list to get one of his pistols. Expensive...but the best usually is.

[Jerry Keefer]

Jerry, I have been thumb cocking the gun with teeny radius but it is kind of an unnatural act, being long experienced with long radius guns.

Hi Jim;

Years (!!!) ago it was common for bullseye guns to have a large radius on the FPS and then have a deep concave scallop machined out of the hammer face from the base up close to the area contacted by the firing pin. This made the gun very easy to cycle. It was the practice at the time, and made 3.5 grains or less of bullseye powder / wadcutters function quite well. Now we are trying to squeeze every possible bit of accuracy out of the guns, and, hence this trend has developed... Both systems work quite well.

Take care

Jerry

[Hill]

Wow. Not raggin' atcha, dog...but is there a specific reason for all that?

Well Johnnie, there's so much interest in what is the perfect cut on these that I thought I'd make some up to sell.

Along with the above described bevelling I took .010" at 30 degrees from both sides on all three working bevels.

Today I'm gonna' setup to make the face of the stop perfectly parallel to the hammer contact surface, and once that's right I think I'll face the stop back less than one degree above and below the FP hole so that the hammer energy is focused at one point only, the firing pin itself.

Once that's right I'll probably be able to use the same fixture set to bevel the outer edges of the face, hone the whole thing carefully using my hardest Arkansas stones. Give it a quick looksee with the microscope. It ought to resemble a fine cut diamond.

When I'm finished I figure that the $12. part should be good for around $150., being perfect as it is. Of course it would need fitting to any individual gun, but quantity discounting will apply.

[Hill]

Jerry, I have been thumb cocking the gun with teeny radius but it is kind of an unnatural act, being long experienced with long radius guns.

Hi Jim;

Years (!!!) ago it was common for bullseye guns to have a large radius on the FPS and then have a deep concave scallop machined out of the hammer face from the base up close to the area contacted by the firing pin. This made the gun very easy to cycle. It was the practice at the time, and made 3.5 grains or less of bullseye powder / wadcutters function quite well. Now we are trying to squeeze every possible bit of accuracy out of the guns, and, hence this trend has developed... Both systems work quite well.

Take care

Jerry

Ya, I did that to the hammer in my own bullseye gun many years ago after seeing it on a professionally prepared pistol. And OH, how I polished that curve! With the light loads and a relatively tight gun every little detail seemed to help.

[Hill]

Nah. Jerry works very carefully and precisely, and imposes tolerance limits on himself that are more closely related to toolmaking than pistolsmithing. If Bullseye competitors are cut from a different bolt of cloth, the smiths who build their guns for'em tend to split hairs 3 and 4 times in the effort to gain just a tiny edge. Jerry is one of those who will split that hair 10 times. That's why there's such a long waiting list to get one of his pistols. Expensive...but the best usually is.


Johnnie, you're confusing everyone. :)

Jerry didn't make the post about using a tool & cutter grinder, I did. I'm sure Jerry has better things to do. :D

[1911Tuner]

Jerry didn't make the post about using a tool & cutter grinder,

Nah. I just responded to Jim's question, and added a little info that may not be general knowledge amongst the membership. ;)

Jerry doesn't really advertise, and seems to prefer to stick to a small but loyal customer base. I guess I outed him. oops...
Sorry Jerry. :D

While I've gotcha online...Why the the multi angles? I remember doin' three-angle valve jobs back in the day...but I'm curious about three on a firing pin stop.

[Greyswindir]

Jerry, Tuner, Hill, etc,

One of my guns is specific to Bullseye shooting...at least that is what my goal is...to use it for bullseye shooting . I installed one of the EGW OS firing pin stops and put a small bevel on the FPS. Since bullseye loads tend to be reduced, and hence softer, how will this effect the cycling of my pistol?

I recently purchased a pack of Wolff reduced power recoil springs so I can tune the pistol to my specific bullseye loads. Most of my loads work fine with the regular 16lbs recoil spring but I'm going to test a new load:

BE powder, 3.5grs. -3.8grs.
200gr. H&G semi-wadcutter, double lube grooves, Lyman #2 lead.
Winchester primers.
Assorted brass, but I generally like to use Lake City.
Crimp is .468"-.469"
OAL is around 1.18, but it can vary a bit depending on case length.

Am I forgetting anything?

I'm a little concerned about timing and how the bevel on this new FPS will effect the system as a whole. After hand-cycling the pistol after the FPS install the slide is only a bit more tougher to rack back.

I want the pistol to stay in lockup slightly longer so the bullet exits the bore during the optimum moment, when the barrel is fully supported during lock-up. This way, I figure the accuracy should improve some. My barrel lockup is tight, no springing...my bushing is also very tight but without any bind that I can feel. The cycling of the pistol is very smooth.

If I'm completely off base or misunderstanding the proper technique to wring out the most accuracy of my pistol then please explain why I am wrong and what I need to do to get the most accuracy out of my wadgun.

I still haven't field tested the pistol since making the above changes. Any advice or help would be appreciated.

Thanks guys.

[Jim Watson]

Not for bullseye, but the gun I have the tiny radius stop in is for light load ammo to be shot at IDPA ESP, power factor 125,000+ = 200 gr @ 625+ fps. It is functional with a 14 lb recoil spring but I cannot tell any difference in the feel of the gun cycling so I guess I do not qualify for the Princess and the Pea award.
Don't know how it will affect accuracy, shoot and see.

[log man]

" The Princess and the Pea Award" whoa, I like it! But I think Jim, that may have dated both of us. :p

LOG

[1911Tuner]

If your gun has an upswept grip safety, and you take a high grip...you'll notice less difference...though the effect will be the same, assuming that you're using all parts of the system.

You can go with a 25-pound mainspring and a 14-pound recoil spring if you'd like. The difference is much more pronounced, and the slide to frame buffering effect is still the same...or maybe a little more.

Experiment with it. You may discover just the right combination that suits you.

.078/16/23 is a suggested starting point. It's not chisled in granite.

[Hill]

"The Princess and the Pea Award".............. :lm:

[niemi24s]

. . . I also grind a 2 degree slope on the face of the stop, and the hammer face, which allows the hammer to rest noticably forward of its normal in battery position, making for even more delay (resistance). A final angle is then ground on the bottom of the stop, to provide an escape angle for slide movement.
Hi Jerry:

Thanks for sharing this with us. Studied your post and then drew this to see if understood it correctly:

http://i129.photobucket.com/albums/p232/niemi24s/scan0011a.jpg

Wasn't sure about your escape angle, so labeled some corners for you to refer to in any reply.

How far off-base am I?

[Jerry Keefer]

niemi24s]


[
Wasn't sure about your escape angle, so labeled some corners for you to refer to in any reply.

How far off-base am I?

Looks pretty darn good. The angle on the bottom is from "B" to "A", and reduces the contact area between the hammer face and the FPS. I blend it into the small radius and finish polish it and the hammer face. I cut 45 degree angles on both sides of the hammer face to slightly larger than the stripper rail. Reduces friction.. No unnecesary contact. I don't like for the FPS to hang below the stripper rail on the slide..and cutting the angle usually fixes that, should it exist. On the bottom right side of the FPS I also grind a small clearance notch to prevent the stop from "ever" making contact with the frame..
One poster asked about accuracy...I don't believe it does any more than contribute to a few extra milli-seconds of bullet bore time before the whole mass starts to move and shooter appeal. Accuracy is a product of many factors related to the barrel dimensions, internal, external, how these dimensions relate to the c/l of the bore and how stable the barrel is supported in battery..

Take Care

Jerry

[niemi24s]

Hi Jerry:

Thanks for clarifying where the bottom angle is.

If your goal is to delay the onset of slide motion, is there really as much of a gap (as I drew it) between the hammer face and Point C on the FPS?

Or do you try to get the hammer face to make as much FPS contact as possible - with a really small a gap at the bottom?

Regards

[1911Tuner]

I don't believe it does any more than contribute to a few extra milli-seconds of bullet bore time before the whole mass starts to move


Uh-oh...

Here we go!

The slide starts to move at the same instant that the bullet starts...assuming, of course...zero headspace. The small radius doesn't delay that...but rather slows it down.

:D

I'll find Tripp's videos and repost the link. It's here somewheres.

[niemi24s]

Uh-oh...Here we go!

Oops!! Sorry 'bout that.

Change "delay the onset of slide motion" to read "slow down the slide's initial motion"

[Niemi goes sheepishly to the blackboard to write ten times "When the bullet starts to move, the slide . . . ."]

[1911Tuner]

Oops!! Sorry 'bout that.


Not you, Dan. Me an' Jerry had a little head-bumpin' on that a while back, and I'm just tryin' to re-hash some old trash. ;)

[1911Tuner]

AHA! Found it.

Jerry...Watch this, and pay particular attention to the last 1911...the one just before the revolver. It's uber-slow...nearly stop-action.

http://www.trippresearch.com/media/movement/hispeedgateway.html


You'll have time to use a pencil point to reference the end of the slide before it starts.

First, you'll see the slide twitch backward a small distance. Then comes a light puff of blowby gas...slide still movin'. Then, the bullet nose peeks out. At that point, the slide has moved about a 10th of an inch. Then, the bullet exits and the fireball follows...and the slide has probably moved far enough for the barrel to be at or just past the start of the linkdown phase.

[niemi24s]

Oh yeah, I vaguely remember that thread from a year or so ago. GBW started it, as I recall. Thing almost made the Guiness Book Of World Records! :D
Cheers

[1911Tuner]

GBW started it, as I recall.

Yup. GB understood things well, but you'd be surprised at the number of people...engineers included...that believe that recoil starts and the slide moves after the bullet leaves the muzzle. I've argued long and hard that it can't happen. At least, not in this universe. :D

Now...Thanks to Virgil Tripp and his efforts in producing those videos...I have been vindicated! Of course, many of the ones who ripped me up the back over it have yet to apologize for their vehement attacks...but that's ai'ght.

Now, I can start over with the point that the bullet also acts to slow things down. I had a go'round with ColtAllure on that one...and one day, I'll get him to see it. Until then, I will endeavor to persevere.

Can I get an OORAH! I CAN'T HEAR YEWWWWW!

[Greyswindir]

Tuner,

People still continue to argue about the reality of barrel locking physics. As you know I posted over at the Bullseye-L list and didn't get a single response. A gunsmith wrongly explained improper barrel locking physics over there so I corrected him, very humbly I might add.. Got called a few names by some nutjob on the list. He really doesn't representation the quality of the guys on the list though. Most of them are nice fellas!

I even brought up the patent info you gave me and still no retraction from the "expert"! :butthead:

[1911Tuner]

I feel yer pain. Wait'll ya tell'em that Kuhnhausen's "Balanced Thrust Vector" description is completely and utterly wrong. They react like you'd stomped a puppy.

:lh:

[Greyswindir]

You got that right! :lm:

One of us "common folks" could never know something that the experts don't know. That would be sacrilegious! :scared:

People will believe anything they see or read, especially if it is on the idiot box or
in a popular book! :D

[Jerry Keefer]

[QUOTE=1911Tuner]Not you, Dan. Me an' Jerry had a little head-bumpin' on that a while back, and I'm just tryin' to re-hash some old trash.

Tuner, are you sure it was me...?? I don't consider myself even remotely capable of debating physics with you... and equal / opposite law is really not debatable. It's fact.. I did not mean to construe that movement does not occur instantly; The word "before" should have read "as". I do know this, that most ransom rest test targets exhibit less vertical stringing with the FPS treatments. Other things, such as lower lug foot print also contributes to this.(less vertical stringing) So, my syntax needs corrected to "the speed with which the mass accelerates".. will you buy that...??

Neimi; The drawing you made is quite represenative. I like to see as much full face contact between the hammer and FPS as possible. Reduces the chance of a concentrated stress point developing into a cracked or broken stop. Never saw it happen on one of EGW's , but it's not uncommon on factory stops..especially 9mm.

Jerry

[1911Tuner]

Tuner, are you sure it was me...??

I b'lieve it 'twas. Can't remember when...but it was on one of these recoil threads. You mentioned that an enginner friend had told you that the slide moves after the bullet exits...and then ya disappeared. It's been so long, that I just thought it was you...so if I've named you on error, please accept my apologies.

Lemme go try to find it...

No harm/No foul, in any event. I enjoy a good head-bump amongst friends most of the time. ;)

[1911Tuner]

Well...Insert foot and swallow hard.

It appears that it wasn't you, Jerry. Memory is the first thing to go, so they say...right after the hearing and the teeth and the eyes and...and...hmmm. I fergit.

Now I gotta go figure out who it was...

[Jerry Keefer]

[QUOTE=1911Tuner]I b'lieve it 'twas. one of these recoil threads. You mentioned that an enginner friend had told you that the slide moves after the bullet exits...

Yep...!!! you're right. I remember that...I was relating his opinion or "findings", not mine, although I confess, that I am not exactly sure or convinced about "some things" , which I'll ponder and keep to myself. For, the only thing that really matters to me and / or my customers, is the result on the target. The subject came up when he and I were discussing frame flex and slide speeds for various calibers. The factory calculates and monitors such things on their products using high tech cameras, / stress / force gages, etc..he is highly skilled in firearm design and I have known him for many years.
Kuhnhausen was also an engineer, and I doubt he would have received his degree without a full understanding of Newton's Law.
I try to resist posting on the forums because of the tendency for the threads to erupt into debate/berate contests, but I enjoy the share and compare concept;(which is almost non existant) the intrig of " inquisitive what ifs " ; and deviation from the norm.. all of which is very hard to find..peer parity is even harder to find...

Take Care


Jerry

[1911Tuner]

Dang! And after that eloquent retraction I made... :D

Anyhoo...on to:

Kuhnhausen was also an engineer, and I doubt he would have received his degree without a full understanding of Newton's Law.

I think not. On the tech page, Kunhausen's original description can be found.

In his description, he uses the term: "Balanced Thrust Vector" and plainly states that the bullet exits, and THEN the slide moves.

Can't happen that way.

For one thing...Balanced Thrust/Force doesn't produce motion. Balanced force means that the resistance offered is equal to the force applied, and the result of that condition is equilibrium. Nothing is moving.

Yet, in the same description, it's assumed that the bullet is moving while this condition of balanced force is in effect. Balanced force and motion can't coexist within a closed system.

If something is in motion, it's offered as proof that the forces are unbalanced. That is...the force applied has overcome the resistance offered...and sets the object in motion. And...in order for the object to remain in motion, the forces must remain unbalanced. Once the outside forces...in this case, wind friction and gravity, or a physical barrier...bring the bullet to a stop...then the forces are balanced and equilibrium is restored.

On to the meat of the description. To wit: Bullet exits/Slide moves.

If the forces applied are sufficient to move both sides of the action/reaction pair...both sides will move...and they'll start at the same instant. To suggest that one occurs, followed by the other...is to imply that the force can be split...or time delayed. That can't happen either. Force is applied in all directions simultaneously and in equal measure. If the bullet feels X units of force...so does the slide. The only way to have the bullet move without the slide moving is to make the slide so massive that the magnitude of force can't overwhelm its inertia...and if we do that...the slide will not move during the ballistic event. Once the bullet is gone, the force is gone.

Another way is to weld the slide to the frame..but then the whole gun will move...and we're back to square one.

This doesn't imply that...simply because the opposite side of the action/reaction pair didn't move, that the equal and opposite reaction didn't occur...just that the equal and opposite force wasn't of sufficient magnitude to make the object move.

You may cut and paste this for your designer friend, as you wish.

[Iron bottom]

Correct information is hard to come by, and recognizing it is sometimes harder. Keep on telling 'em, Tuner. The more folks know about the 1911, the longer it will be around.

[1911Tuner]

Keep on telling 'em, Tuner. The more folks know about the 1911, the longer it will be around.

I tries. Lord knows I tries...

All this will answer the age-old question:

"What happens when an irresistable force meets an immoveable object."

The answer is..."Nothing"

Shall we explore the bullet's function in delaying the movement of the slide and the opening of the breech? :D

We do understand at this point that the "Locked Breech/Short Recoil Operated pistol is actually very nearly a delayed blowback design....Right?

And that...whether straight blowback or locked/short recoil operated...both operate by means of recoil impulse...Right?

Let the fur fly! Ah'm yuh Huckleberry!

[niemi24s]

I like to see as much full face contact between the hammer and FPS as possible.
Hi Jerry:

Thanks again. Think I undertand it 100% now - and it makes perfect sense.

Ended up doing essentially the same thing that you do during one EGW FPS installation. Not for the reason you do it, but because the hammer face on the gun was convex and contacted the FPS only at the bottom!

Rather than risk goofing up the hammer, the FPS was dished out to allow the hammer to hit the FPS at the level of the FP. With no smithy-type machinery, it took a lot of patient grinding with the Dremel!

Cheers

[niemi24s]

Can I get an OORAH! I CAN'T HEAR YEWWWWW!


OORAH!!!! :D

[Greyswindir]

Tuner,

"What happens when an irresistable force meets an immoveable object."

The answer is..."Nothing"

The question is oxymoronic, isn't it Tuner?

If an irresistible force meets an immovable object, then like you stated, nothing happens.

Are you trying to confuse us slower children or what? :)

[Hill]

Aren't there two variables not discussed - the spring and the cartridge load? While the bullet moves with small resistance energized by the size of the charge that propels it, the slide works against it's own weight plus whatever additional resistant force is applied by the recoil spring.

Depending on the setup chosen by a builder in hopes of a balance of these it's quite possible that the 'balanced thrust vector' can allow for the bullet's exit prior to any movement of the slide.

I think that the "puff of smoke" is the bullet exiting the barrel and that the "nose of the bullet peeking out" is the signature of the force field created by the residual sonic pressure of the explosion of the charge, and the Jerry Kuhnhausen is right.


...........dum-de-dum-de..........(whistling a silly tune) :)

[1911Tuner]

While the bullet moves with small resistance energized by the size of the charge that propels it, the slide works against it's own weight plus whatever additional resistant force is applied by the recoil spring.

Nope. The bullet and the slide "feel" exactly the same force. If that force is large enough to move the bullet out of the case...100 pounds PSI of force required to do that...and into the rifling...where it becomes even harder to keep accelerating the bullet...it's more than enough force to move the 14.4-ounce slide against 8 pounds of preload resistance provided by the recoil spring.

Depending on the setup chosen by a builder in hopes of a balance of these it's quite possible that the 'balanced thrust vector' can allow for the bullet's exit prior to any movement of the slide.

Balanced forces and motion cannot exist at the same time within the same closed system. Can't happen. If anything is moving, the forces are unbalanced.

I think that the "puff of smoke" is the bullet exiting the barrel and that the "nose of the bullet peeking out" is the signature of the force field created by the residual sonic pressure of the explosion of the charge,

Regardless...the slide is plainly moving before the bullet becomes visible.
and the Jerry Kuhnhausen is right.

Nope. Kuhnhausen was no doubt a fine and knowledgeable gunsmith...but he dropped his candy on that one. It was edited out in the later editions of the shop manual...and replaced with something that seems more accurate...so that suggests that somebody whispered in his ear: "Uh...Jerry, ol' buddy! That can't happen!"

[niemi24s]

. . . it's quite possible that the 'balanced thrust vector' can allow for the bullet's exit prior to any movement of the slide.
What force, then, causes the slide to move (with respect to the frame) after the bullet has departed the barrel?

Whatever remaining pressure exists in the barrel when the bullet departs must certainly be wa-a-a-y less than Tuner's blood pressure right about now!:D

Cheers

[1911Tuner]

What force, then, causes the slide to move (with respect to the frame) after the bullet has departed the barrel?

The same thing that keeps the bullet in flight after the driving force has been removed. Conserved momentum.

Newton 1B:

Objects in motion will remain in motion unless and until influenced by an outside force.

[niemi24s]

Hi Johnny:

What I really meant to ask in Post #55 was "What force, then, causes the slide to begin to move (with respect to the frame) after the bullet has departed the barrel?"

And, the question was meant for Hill.:)

I'm with you on this one: the slide starts aft on the frame the instant the bullet starts forward (assuming the case head's against the breechface when case/bullet separation begins). And if the case head's not against the breechface, it'll probably get there even before the bullet gets part of the way into the rifling!

Cheers

[1911Tuner]

And if the case head's not against the breechface, it'll probably get there even before the bullet gets part of the way into the rifling!

Oh...Count on it, unless the headspace is so far outta spec that the gun is dangerous to fire...and even then...it won't get completely engraved by the rifling. As you showed us with your nifty little hydraulic gizmo, the level of force needed to break the bullet loose from the case's grip is more than enough to move the slide.

[Hill]

It takes far less force to move the bullet than it takes for the heavier slide burdened by spring pressure and metal contact pressure which increases against slide movement after firing.

The charge pressure acts immediately upon the bullet but has not built to it's full potential until the bullet has begun moving because it needs the new room to expand. It moves bullet only as pressure builds against the slide boltface/breechface until it's sufficient to overcome the resisting pressure.

If you envision the slide being welded to the frame, as in the example used above, until there is enough cumulative pressure to break the weld and set the slide free then you know that the time it took for that tension 'weld' to break is more than enough for the bullet's exit. The weld breaks at the exact instant that the bullet leaves in a well timed pistol. An oversprung or overtight pistol fails it's slide functions, ramified in those ways which we know too well - failure to eject, failure to feed. But the bullet will leave no matter if the slide moves, is welded, or simply late, slow, and cranky......:)

[1911Tuner]

It takes far less force to move the bullet than it takes for the heavier slide burdened by spring pressure and metal contact pressure which increases against slide movement after firing

Niemi and I would beg to differ. He proved it a while back with a dandy little hydraulic device that he fabricated. It took...IIRC...something over 100 pounds PSI to move the bullet in a a case that was sized and taper crimped in a reloading press. If the bullet had been sealed in with asphalt cement...it would have required more force to start it.

It moves bullet only as pressure builds against the slide boltface/breechface until it's sufficient to overcome the resisting pressure.

And when the bullet moves in one direction, the case moves in the other direction. Assuming zero headspace...by the time the bullet/case assembly start to separate, there's more than enough force bearing on the slide to move it.

If there's .010 inch of headspace...the time lapse between the beginning of the case's movement and its contact with the slide can pretty much be ignored. i.e. How long does it take a bullet to move .010 inch from a standing start...as the pressures scream toward peak?

And...pressure/force builds in all directions at once. Since it this instance, it's a vectored force...meaning that it has both magnitude and direction...whatever the breechface "feels" the bullet feels also.

[berkbw]

what makes the slide move in relation to the bbl is a combination of link down + lowering of lug locking gas pressures. Recoil from acceleration of bullet and powder are also players.

It would, to me, be interesting to have an interactive graphic where bbl length, bullet mass, powder type [fast - slow], charge wt., and case pressure were variable. Unlikely to be able to manipulate bullet seating depths, I guess.

b-

[1911Tuner]

Dang! Wha' Hoppened??? Screen went blank.

Anyway...

Hill...Action and reaction begin at the same instant. A simple demo is in order.

Go push on a wall. Notice that the instant you push, you GET pushed by the wall...through the vectored force provided by your arm.

Go pull on a car bumper with bicep flexion, bending your arm at the elbow. The instant that you exert pulling force...you FEEL a pulling force in equal measure...and you get pulled by the car. Again, the vector is provided by your arm.

There is no delay. There is no "First one, then the other" in an action/reaction force pair.

For every action, there must be an equal and opposite reaction. Equal means equal...and Kuhnhausen blew it.

[Hill]

You're oversimplifying.

Taking your own example of bicep flexion and car bumpers ask how long before the bumper actually moves does your bicep go kerplooy and you, in an unrelated movement, sink to the floor screaming in pain. An awful lot of things happened and there was an extreme amount of movement up to and including the failure of your tendons - yet that bumper attached to your car didn't move one lick even though, as you say, the forces upon them both were equal at the outset. for accuracy there must be an exited bullet prior to a disturbed barrel. Since there is a very high potential For accuracy this must be true. In a well set up 1911 pistol there cannot and is not any movement of the barrel/slide (assembled in lockup) before the shot is away and it is proved each time a pistol fires to exact point of aim.

Sir Isaac lived a long, long time ago and he didn't pay attention in school. :)

[1911Tuner]

You're oversimplifying.

Taking your own example of bicep flexion and car bumpers ask how long before the bumper actually moves does your bicep go kerplooy and you,

And you're overcomplexifying. (Izzat a word?)

The wall and the car don't move because the magnitude of resistance is greater than the applied force. That doesn't mean that a force wasn't imposed on the wall or the car. It just means that the force wasn't large enough to overcome its resistance.


Let this sink in:

If the magnitude of the force applied is great enough to overcome the resistance of both objects, it will set both objects into motion at the same instant. If the force isn't great enough to move the reaction side of the action/reaction pair at the same instant that it moves the action side...then the reaction side won't move at all.

Action and reaction forces were still applied. It just wasn't enough. You can theoretically build a .30 caliber rifle so massive and so heavy that firing it will produce zero felt recoil...but that doesn't mean that recoil doesn't occur. It just means that the rifle is too heavy and too massive for the forces generated to make it move.

[berkbw]

Ya know, H - Tuner has a pretty good grasp on what many would term elementary physics - Newtonian, and that stuff. Since both he and I are almost as old as dirt, I [we?] remember a lot of this old stuff. There have been changes - like have you bought an apple lately?

I must have missed it, but I think that the topic[s] of fun here are not being equally displayed/argued in metafor.

'course, I majored in engr. phys & psych - and you have seen where I have gotten from that, eh?

I think that I must be just jealous, as I am always the one that is said to be argueing just for the sake of argue - [my Dad said " Just to hear your head rattle."]

Fun enough -
b-

[Greyswindir]

Hey guys,

Man do I wish I could have gotten into this debate during the first few posts but I was busy taking a Sunday nap! :bed:

Forget about it Tuner, you've explained it beautifully. If after all that you still get resistance. I doubt it's worth it to keep going. It's not like there is a misunderstanding and people need more info...They just disagree! Regardless of all the factual information that has been offered. :butthead:

Simple physics prove what you've been explaining. Just because the equal and opposite reaction is "reacting" doesn't necessarily mean you'll be able to visually observe it! When the mass of the other object (car plus bumper) is greater then the original force working upon it (person pushing on bumper has a lot less mass!) the opposite reaction is there, you just can't see it because the greater mass is resisting it.

Wait until you explain what is going on between the barrel lugs and the slide lugs! :scared:

Oh boy! :rolleyes:

[1911Tuner]

Ya know, H - Tuner has a pretty good grasp on what many would term elementary physics - Newtonian, and that stuff.


I try...;)

The first thing that the blind followers of Kuhnhausen is just this:

...That the force required to move the bullet within the case is more than enough to move the slide. That much has been demonstrated and proven by our resident mad scientist, Niemi.

Then, they have to wrap their heads around a basic physical fact:

To say that the slide stands still until the bullet is gone is to state that the forces are being split...acting first in one direction, and then...later on...in the other. That can't happen. You can't have force in one direction only. You especially can't have one force, followed by another separate force in the same closed system during the same event. These are both physical impossibilities. In another universe, maybe...but not in this one.

And understand, that without exception that:

Force is exerted in all directions at the same time in equal measure. Because the closed system of a gun barrel and breechblock causes it to be a vectored force...a directional force...the actions resulting from that applied force are directed forward...and backward.

Think of an air burst vs a shaped charge.

[Hill]

There, you see, Johnnie, your own agree'er has said that the bullet leaves the barrel before the slide begins to move in: "Just because the equal and opposite reaction is "reacting" doesn't necessarily mean you'll be able to visually observe it! When the mass of the other object (car plus bumper) is greater then the original force working upon it (person pushing on bumper has a lot less mass!) the opposite reaction is there, you just can't see it because of the greater mass!"

Exactly. I didn't say that forces were not at work and I didn't say that those forces were no equal. As Greysw paraphrases me, so it is.

And Berkbw, if you share a number of years with tuner and base anything on that fact you may as well sit down because I outrank tuner in years by more than a few. He's just a pup. :)

[1911Tuner]

There, you see, Johnnie, your own agree'er has said that the bullet leaves the barrel before the slide begins to move in: "


Hill...Buddy! I don't know where you got that. Go watch the video again. It can NOT happen! Not in the 1911 pistol as we know it.

If the bullet is gone before the slide moves...the slide WON'T move.
Because...once the action side of the action/reaction pair leaves the system...the forces that compel the event leave behind it.

[Hill]

tuner said: "To say that the slide stands still until the bullet is gone is to state that the forces are being split...acting first in one direction, and then...later on...in the other. That can't happen. You can't have force in one direction only. You especially can't have one force, followed by another separate force in the same closed system during the same event. These are both physical impossibilities. In another universe, maybe...but not in this one"

You apparently have never set a claymore mine.

[Hill]

The energy to move the slide builds all the while the bullet scoots. Nevermore.

[1911Tuner]

You apparently have never set a claymore mine.


I've set several. The reaction force is directed to the rear. Don't believe it? Stand behind one when you hit the clacker.

[1911Tuner]

The energy to move the slide builds all the while the bullet scoots.

Go watch the video. Watch it carefully. The slide is moving before the bullet reaches the muzzle.

[log man]

In a well set up 1911 pistol there cannot and is not any movement of the barrel/slide (assembled in lockup) before the shot is away and it is proved each time a pistol fires to exact point of aim.



Okay, a well set up pistol fires to an exact point of aim, as a result of doing the same thing each time it is fired.

The reason that the slide and barrels .100" movement to the rear with out effecting accuracy before the bullet exits, is due too JMB's design of the mechanism of disengaging the barrel from the slide. The link, which when in battery is angled forward of the center of the slide stop pin around which it rotates.

This genius of timing means that when the gun is fired and the slide and barrel begin moving to the rear the link has to move from over center to dead center and then to past center before it begins too apply a downward force on the barrel. This takes approximately .100" of travel, and the bullet has left the building on the same trajectory that it began when the primer was struck. ;)

LOG

[Greyswindir]

Hill,

I agree because it is true, not because I like tuner, though I do like the old guy!

And I was speaking about not visually seeing the car move because of its greater mass in relation to the person exerting force on the bumper of the car.

I made no mention of the Tripp slo-mo video!

Please Hill, read the post carefully. If you would have done that the first time around you would have never misconstrued what I said/wrote. :D

P.S,

No neat explanation of what is going on between the barrel lugs and the slide lugs during the opposite and equal reaction? I'm disappointed! That's my favorite part!

[1911Tuner]

Log...A better demo is to fire a group at 25 yards with .357 revolver in a normal grip.
Then...place a sandbag under the butt of the gun, and use just enough control to keep it from jumping off the bench...finger and thumb will do...and fire another group using the same aiming point. The point of impact will change radically...mostly high. What we glean from this is that the gun is in full recoil while the bullet is in the barrel.

[1911Tuner]

No neat explanation of what is going on between the barrel lugs and the slide lugs during the opposite and equal reaction? I'm disappointed! That's my favorite part!

I'm havin' trouble enough explainin' Newtonian Physics, thank ya very much!

:lh:

[Greyswindir]

Good point! :D

I've set several. The reaction force is directed to the rear. Don't believe it? Stand behind one when you hit the clacker.

Now THAT is funny! :lm:

P.S.,

The agreer'

[Hill]

Log man.................shhhhh..;)

[log man]

Log man.................shhhhh..;)


OOHHH.........sorry, ahhh...never mind mmmm......sometimes I forget that the object is too jerk the guru around just for fun duh.............. :)

LOG

[1911Tuner]

Whoa up! I think I've found the source of Hill's misconceptions.

When he said:

"The force builds while the bullet scoots."

It hit me that he believes that pressure builds gradually...when it's actually just the opposite. As the bullet scoots...pressure drops...rapidly.

The pressures in a pistol cartridge peak quickly and suddenly. Typical pistol powders hit peak pressure within a half-inch of bullet travel, or less. With some especially fast powders...peak pressure can occur before the bullet leaves the case.

Likewise...about 90% or more of the total muzzle velocity occurs during that violent climb to peak pressure...and recoil impulse follows. This is proven. I've done it.

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.

[1911Tuner]

Hill...Are yew (expletive deleted) my Marine Corps again?

[Greyswindir]

Tuner,

Clear out some of your pm's...it is jammed packed. You won't be able to receive any more pm's until you delete a few messages.

[Hawkmoon]

You're oversimplifying.

Taking your own example of bicep flexion and car bumpers ask how long before the bumper actually moves does your bicep go kerplooy and you, in an unrelated movement, sink to the floor screaming in pain. An awful lot of things happened and there was an extreme amount of movement up to and including the failure of your tendons - yet that bumper attached to your car didn't move one lick even though, as you say, the forces upon them both were equal at the outset. for accuracy there must be an exited bullet prior to a disturbed barrel. Since there is a very high potential For accuracy this must be true. In a well set up 1911 pistol there cannot and is not any movement of the barrel/slide (assembled in lockup) before the shot is away and it is proved each time a pistol fires to exact point of aim.

Sir Isaac lived a long, long time ago and he didn't pay attention in school. :)
No, Sir. Tuner is not over-simplifying. You are.

Classic example from my youth: I used to be a sailing instructor in my teens. The boats we used were traditionally-built, wood plank 20-foot sloops that probably weighed about 1,000 pounds dry. Then they carried 800 pounds of pig iron in the bilge as fixed ballast. The mast and boom were also wood, and they were equipped with anchors, rope, paddle, yada yada. All in all, they were weighing in at just about 2,000 pounds in use. Back in those days I weighed in at about 150 pounds soaking wet -- which we'll come to in a moment.

One fine day I was standing on the foredeck of one of these little sloops, and decided I needed something that I had left on the dock. I failed to notice that the boat was close to the dock due to the direction of the tide, but the ropes tying the boat to the dock had a considerable amount of slack. So I commenced a graceful leap from the foredeck of the boat to the dock.

My graceful leap quickly transmogrified into an ungainly "plop" because the force of my leg pushing back against the mass of that 2000 pound boat was sufficent to propel the boat far enough backward as I moved forward that my leading foot fell short of the dock, and I hit the water between the dock and the boat.

The principle is exactly the same as the 1911. I was the bullet. The 2000-pound boat was the slide. The muscle in my leg was the gunpowder. I assure you, the moment my leg started to push me forward it also started to push the boat backward. I felt it. It was definitely one of "those" moments, because I could not undo the jump, yet I knew long before I hit the water that I was NOT going to make it to the dock.

Physics is physics. It wouldn't matter if the 1911 slide weighed ten tons -- at the moment of ignition, the same force that propels the bullet "forward" will be pushing "backward" against the slide. The heavier the slide the less movement there will be, until you ultimately get so heavy that we don't have instrumentation capable of measuring the amount of movement -- but it'll still be there even if you can't see it or measure it.

Delaying the inception of slide movement until after the bullet has departed the muzzle is a physical impossibility. The relative differences in mass affect the relative rates of acceleration of the bullet and the slide, but the slide has to begin moving when the bullet begins moving. If it worked the way you propose, I would have landed on the dock before the boat started moving away from me when I jumped.

[Greyswindir]

Hawk,

You explained it much more gracefully then I did but my explanation perfectly parallels your explanation. I hope you didn't wind up hitting the dock with your face while the rest of you went into the drink? Ouch! :D

[1911Tuner]

Good analogy, Hawk.

Now then...If alla yew (expletive deleted) birds are done finger(expletive deleted) the Gunny...I'm ready to deform yer pointy little heads with somethin' real tough.

Lets start us a thread on how the bullet figures in with delaying the breech opening.

Shall we?

:cool:

[Greyswindir]

Go for it!

But ask us some questions to see who can figure it out (for us younger guys who still need to keep up on our book learnen') I think it would be entertaining and highly informative.

[Hill]

OOHHH.........sorry, ahhh...never mind mmmm......sometimes I forget that the object is too jerk the guru around just for fun duh.............. :)

LOG

"A man that flattereth his neighbour spreadeth a net for his feet"
-prov.29

1911Tuner: "Hill...Are yew (expletive deleted) my Marine Corps again?"
A little bit.


Hawk, You say you were a sailing INSTRUCTOR??? :lm:

[1911Tuner]

A little bit.

Well, now! Ain't we the commedian?

There's another thread waitin', Jarhead. Git some!

:D