Clinic-3: BFC

[1911Tuner]

Barrel Fittically Correct.( In case anybody was wonderin'.) :p

Note:

Although I wracked my brain in the effort to remember all the details of this saga as best I could, some of the dimensions and procedures given may not be entirely accurate...but they're close. After nearly 40 years, the little things tend to get a bit fuzzy.
*****************************************************

I arrived at the shop two weeks after I started on my journey to truth and wisdom, a wiser but apprehensive lad. Having learned my lessons via the long, hard route...I was duly chastised, and today was the day that I would do this barrel thing for keeps. It was a brightening, nearly sunny Saturday morning...0500 hours. Henry figured that I'd need to get an early start. He was right.

Uncle H opened a package that contained a match-grade barrel, still covered with the odd-smelling oil that had been there for many years. Void of proof marks, this wasn't a Schuemann or a Kart or a Storm Lake. This one would be worth mucho dinero if it hadn't been opened that Saturday.

All critical dimensions were oversized for hand-fitting...and the chamber was semi-finished.
Short reamed by .015 inch so that the final headspace could be chosen by the armorer. A true hard-fit barrel. I was scared.

The first step was to gauge the slide for lug locations and record them. The measurements were done 3 times, and an average of the three taken for a final fit dimension. Likewise for the barrel, from hood to front lug faces. This barrel was to be fitted to pistol #2...since the first barrel was dead in the water. It was a 1944 production Remington Rand.

Henry told me that the process would be a bit different this time, since the second thrust face in the slide was located a bit too far to the rear. I wouldn't start with the hood this time. I would start with the #2 barrel lug.

Checking the final measurements determined that I would have to cut the face of the #2 barrel lug back by about .003 inch in order to bring #1 into contact. This cut must be made straight and true, and no more than .0005 inch out of square. That's a half-thousandth of an inch. If you had a sheet of steel that thin, you could probably read through it. It was to be one stroke of the file and measure...repeat, until the dimension was reached.

Lug #1 was within reach...On to lug #3. That one was now almost .005 inch off the slide's abutment. Too far for proof equalzing. Time to cut the faces of lugs 1 and 2 by enough to
bring #3 into play, or at least close enough to equalize it by proof-firing...which is a maximum of .002 inch. This meant that the static headspace would be increased by .008 inch by the time all lugs were equalized, leaving .007 inch at most to finish, depending on how close I could get it
in the initial fit. A sheet of 20-bond typing paper is barely more than .004 in thickness, so I'd have to be deft with the reamer. The fact that it was spankin' new would make the job easier, but because it was so sharp, just a little too much pressure
would cut farther than Henry wanted me to. Initial static headspace was to be set at .895 inch...or .003 inch under minimum.

It took me 6 hours to get the lugs into contact. #2 was solid. The others were lightly kissing,
allowing just a little for final equalizing. Now to the hood. it had to be carefully cut...by hand...to allow the sides to enter the recess with just a bit of light contact. Final adjustment to be made after the length was set. Length was to be cut so that the barrel would enter the slide with medium thumb pressure. A square was used to check the lateral misalignment, and adjustment made on one side of the hood. Final clearance was just .002 inch per side with a light interference fit at the breechface. Static headspace checked with a special short GO gauge and a strip of paper suggested an approximate dimension of .890 inch. I wanted to go home, but I had to stay with it, if I had to stay until midnight.

On to the lower lug and the test fit into battery. There were no handy lug cutting tools...just a round file, a scrape made from a lathe bit...and my trembling hands. The round file was used in a draw-file motion, pulling it sideways on the lug to shorten and blend with the rear radius.
The scrape was used for fine adjustment after trial fitting. The gun finally went into battery with hard pressure on the back. The slide was just barely rearward of the frame. The disconnector reset as per design, but the thumb safety notch was a little shy of perfect alignment. Vertical lockup was tight, to say the least.

Out came a ground and hardened .196 rod and the lapping compound. The rod had a T-handle
brazed to one end. Another identical rod with a .198 diameter was also on the bench...in case we needed it...and the lapping began. I moved the slide forward and inserted the rod through the slidestop pin hole...and let it go under recoil spring pressure...and turned the rod to walk the slide forward. Reapplying the compound on every other pass, I got the slide to battery
about the time my hand felt like IT was locking up.

He handed me a slidestop. The slide refused to go smoothly, and we turned to the .198 rod for the final fit. It didn't go much faster than the initial fit because after every pass, I had to take the gun apart...rinse out all the compound...and try the slidestop. When the slide finally went to battery on the slidestop...just a wee bit tight...lapping compound was again applied to the
stop crosspin, and the slide hand-cycled about 5 times. Perfect!

Whoops! A problem with the barrel to slide clearance in full linkdown emerges...The clearance is good at .015 inch...but it occurs at .300 inch of slide travel instead of .250 inch. OMG!
Not a biggie, sez Uncle Henry. The barrel is stopping on the vertical impact surface like it should. The problem is at the front radius of the lower lug. It's not letting the barrel drop fast enough. Reshape it to reduce the sizeof the radius...elongate the top of the link hole just a bit,
(Seems like it required .002 inch) and you're probably good to go. Turned out that he was right. Imagine THAT!

Lug equalizing was done under pressure with handloaded rounds with cases measured to
insure that the gun would go to full battery. Three rounds later, we returned to the bench and
looked things over. The short GO gauge was inserted...but this time the strip of paper slipped out from between the gauge and the slide without tearing. Headspace was estimated at
.894 inch. The lugs had seated and increased the static headspace, and this about was as far as it would go. Time to decide. Was I building the gun for maximum accuracy...or was maximum reliability my goal? I opted for reliability. Henry was a little disappointed, but let me go with that. He said that I'd need to open up the hood clearance another thousandth or two per side. Okay then...Remember to cut a bevel on the underside of the hood. Yessir.

He attached a stop collar onto the reamer and reminded me of the "Rule of Halves." I placed the reamer into the chamber and pushed it into contact with the shoulder... and slid the collar
lightly against the chamber hood. The reamer had a little light interference in the forward (approximately) 32nd inch of the chamber, and he told me to turn it once slowly to remove the taper...then bring the reamer out and clean the chips off. The second pass still suggested there was still a little taper, and the process repeated. The third pass put the reamer into solid contact with the shoulder. I slipped the collar back into contact with the face of the hood...under its own weight only...and locked it down. With light forward pressure on the tap handle, I turned the reamer once...backed it out...cleaned the chamber, and checked the headspace with a standard .898 GO gauge. Almost! Cleaned the reamer again and
reset the stop collar. NOT...quite! A tick more. DAMMIT! Too much! Henry reckoned that my final static headspace was .900 inch. Firing the gun a few hundred rounds would probably open that up by maybe another thousandth as the lugs settled in and took a final, solid seat. The barrel was now not only precisely fitted to the gun...it would likely wear completely out before the headspace would increase to the point of causing a problem. The locked breech pistol was now as strong as the design would allow. The light "seating" flange was dressed off the lugs with a stone. (Lookin' good, just like Hollywood!)

The bushing fit was straightforward, done pretty much like any other match bushing with just the tiniest bit of interference as the barrel approached final lock without springing or producing any linkdown problems. That part I was able to do without coaching, and the gun was wicked accurate. I actually wound up fitting a second, looser bushing to the gun for reliability...but I don't think it was ever used. I'm still tryin' to buy the gun from my cousin...but he's a tough nut to crack. It'll still part your hair at 25 paces. I shot it about 3 years ago. Cuzzin refuses to sell, but will trade for my Union Switch...NOT!

[AnthonyRSS]

I cannot believe you can remember those numbers.
It is amazing. Now I need to learn how to fit a barrel.

When are you going to give an online class? ;)

[1911Tuner]

I cannot believe you can remember those numbers.
It is amazing. Now I need to learn how to fit a barrel.

When are you going to give an online class? ;)


LOL...I probably didn't remember'em exactly. Like I said...it's been a while. I wrote'em down as nearly as I could remember after a lot of rememberin'...so they'll be pretty close.

Online class? Ain't gonna happen, mah fren. It's more a logical, common sense approach anyway. Nothin' voodoo or black magic. Practice on a junk barrel with a file until you can cut straight, and fill up on patience before ya start. You can get the hood tig-welded on the cheap. The slide gauges are the tough part to arrange. High-dollar to buy, and tricky to make. Mine are home-cobbled, and butt-ugly, but they do the trick. ;)

Figure out which lug will hit first, and go from there.

[1911Tuner]

That sound! Could it be wheels turnin'? Will Brownells sell many square pillar files in the near future? :D

[AnthonyRSS]

I'll go for it one day. When I have more disposable income and can buy the right tools- it always makes things easier. Right now I've got a Nork I'm finishing up...Kinda wish I'd left it alone. If this trigger job turns out swell, I'll post pictures after I park it.

I never could leave well enough alone.

[1911Tuner]

No mo' qestions...I guess either everybody's clear on it...completely confused...or figgers that I'm fulla sheep dip and just don't wanna say so. :D

Just a sidenote...

Many smiths feel that horizontal engagement on the first lug is adequate, and...assuming that they get full vertical depth...it is. It won't maintain specs as long as with all three lugs sharing the load, but it'll do for a quick and easy barrel upgrade. I've used the Kart Easy-Fit system in two guns with good results, but the guns aren't destined for hard use...so it'll do.
The question is: Are you satisfied with "adequate" or do you want it right?

Equal engagement is how the gun was designed to work because it provides
full strength and rigidity in the lockup. The 1911's radial lugs are fairly small,
and don't provide a lot of surface area to bear the shock and stress of
hard use in the long term before deformation sets in...with the resulting increase in live headspace...and the higher the pressure from the ammo, the faster this happens. Correctly fitted, the rifling will be worn nearly smooth well before headspace opens up enough to cause a problem...so long-term durability is the main advantage of equalized lugs. Accuracy can be had with just one, provided everything else is well-fitted.

The drawback with the one lug system is in knowing WHICH lug is bearing the brunt. Since you can't actually see which one it is, you have to use the gauges to find out. Even on the first lug, it's impossible to tell because even though it's where you can see it, the slide abutment face is under a short projection on the slide...and if another one is actually taking the thrust, and #1 is only 2-3 thousandths off...it may LOOK like it's engaged, when it's not.

A wise pistol wrench (Metalsmith) said it best:

"I only know what I can measure."

Words to remember when approaching a barrel fit, regardless of which method you choose.

Luck! ...and happy Turkey Day to all!

[garrettwc]

No mo' qestions...I guess either everybody's clear on it...completely confused...or figgers that I'm fulla sheep dip and just don't wanna say so.
I'm sure I'll have plenty of questions once I get time to fully digest it. I'm working my tail off today so that I can have the long weekend off. ;)

[auto45]

First post on this forum and great job.

1911Tuner has helped me with bbl problems on another forum, so his advice(teaching) is always good, as you already knew. :)

IMHO, with shooting a fair amount of rounds through 2 Colts, I would say 80% of my "problems"/breakage is caused by improper bbl fit.
None of it surfaced prior to 8,000 rounds I believe, but frustrating and expensive repairs.

After re-reading this post, I wonder how, "in the good old days", how much time it took the craftmans/gunsmiths that worked for Colt to fit the bbl. Could they do it that fast, so that it would last...or is it possible that most shooters in that day, didn't shoot enough rounds to really test the long term fitting of a bbl?

Regardless, it does pay to have it fit right in todys world.

I thought with all this fancy, high tech CNC machines, etc, etc they could do a better job with bbl fit. Maybe, I had two "Monday" guns or the wrong brand...don't know.

Thanks and Happy Thanksgiving.

[1911Tuner]

T'was asked:

>>After re-reading this post, I wonder how, "in the good old days", how much time it took the craftmans/gunsmiths that worked for Colt to fit the bbl.<<
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In the old days, barrel steel wasn't as hard as the newer stuff they make'em out of today. The higher degree of malleability gave a little more leeway in proof equalizing, so the initial fit didn't have to be quite as precise. Since the headspace tolerance is so wide on the 1911, all the armorer had to do was make sure that the slide would go to battery on a GO gauge, and fail to close on a NO-GO after equalizing. (and dress the light flanging on the lugs that resulted from the process.) As long as it passed that test, the gun was good to go, and it was out the door.

The above outline describes precise fitting of a barrel, and the tolerances are held much closer than an ordnance-spec gun. Unless your goal is wringing all the accuracy out of the gun that you can, you don't need to get quite that
picky. If the lugs equalize, and the headspace is within the .022 inch window, the fit is good. Even if you're only able to get two lugs bearing
equally, you're ahead of most factory-installed barrels..which are essentially drop-ins, and only occasionally have more than one lug in the fight...and only rarely is it the strongest one. If you can bring lugs 2 and 3 to bear and leave #1 kissin' air, it's still at least as strong as #1 alone..and probably stronger, assuming good vertical fit. If you can get 90% depth, along with #1 and one of the others...and maintain mid-spec headspace...you've got a barrel that'll likely go in excess of 50,000 rounds before needing attention.

[John]

I have a question, that I die to ask:

I can understand the load bearing nature of the lugs. But what about the barrel's hood? Let's say that we have a pistol where the lugs are fitted properly, i.e. making contact as they should. Also, since this is the ... perfect pistol, when the barrel is locked in the slide (fully forward position), the barrel's hood is also touching the breechface.

So, now as the slide/barrel combo starts to recoil, ins't the barrel hood participating in sharing the load of the thrust? Until the barrel starts unlocking, I think it is.

Come on Johnny, enlighten me.

[1911Tuner]

I have a question, that I die to ask:
So, now as the slide/barrel combo starts to recoil, ins't the barrel hood participating in sharing the load of the thrust? Until the barrel starts unlocking, I think it is.

Come on Johnny, enlighten me.

Nope. Think about the way the pistol operates, bossman. Remember that the front faces of the barrel lugs engage the rear faces of the slide's lugs.
When the bullet hits the rifling under pressure, it holds the barrel hard forward. That same pressure is slamming the slide backward. That would tend to try to force the breechface away from the hood. If it's any consolation, I once had a gunsmith give me a lecture about "The Forgotten Fourth Lug." He was talking about the hood and breechface junction. Took me half an hour to get the light to turn on for him. There are a lot of practicing smiths whose specialty is the 1911 pistol...who don't completely understand how it functions.

That's why excessive headspace due to lug setback is dangerous. The slide moves backward and away from the barrel by the same amount of the deformation, partially opening the breech. The case backs out as it follows the slide, and loses chamber support. Ka-boom!

[John]

So, in reality, the barrel is pushed forward? I am afraid I do not understand. Especially when you say that the same pressure is slamming the slide backward.

In my (non-gunsmithing) mind, while the bullet is still in the barrel, pressure pushes at the base of the bullet and at the inside area of the case head. Due to the mass difference, the bullet moves forward much faster than the slide/barrel (which are engaged) move backward, so the bullet exits the barrel and now the slide/barrel combo is moving rearwards. The reason they are moving rearwards, is of course because the lugs are engaged. If as you said the front surface of the barrel lugs are engaging the rear surface of the slide lugs, and the hood is touching the face, and since it is the barrel that initiated the movement to the rear, not the slide, the area that puts pressure on the slide to move back, is the hood, not the lugs.

I am confused, even more so now, than before asking.

[1911Tuner]

Almost there, boss. The barrel doesn't initiate the slide's movement. The thrust vector between the slide and bullet does that. The slide pulls the barrel backward. If the barrel drove the slide, the lug contact areas would be reversed. Rear of the barrel lugs to front of the slide lugs.

The pressure of firing drives the barrel and slide in opposite directions. Due to the slide's greater mass, it conserves its momentum more efficiently than the bullet does. The greater mass overcomes the lesser mass...and the unit moves backward. In reality, the recoil-operated, locked breech 1911 operates exactly the same way as a straight blowback. It just uses a different mechanism to delay the opening of the breech until the bullet exits and pressures fall.

[garrettwc]

The thrust vector between the slide and bullet does that. The slide pulls the barrel backward.
I think I got this. Physics 101 - for every action there is an equal and opposite reaction. The force of the exploding powder/gases is pushing the bullet out of the barrel and exerting force onto the barrel pushing it forward. At the same time the gases are pushing rearward against the spent cartridge and breechface.

If it weren't for the lugs locking the two together, the barrel would slide forward to the extent the link will allow and then stop. The slide would go rearward until the dustcover hit the frame bed. The gun would not come back into battery and the barrel would have to be "reset" by hand after each shot.

[1911Tuner]

Bingo garrett...except for the part about:
>The gun would not come back into battery and the barrel would have to be "reset" by hand after each shot.<
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You forgot about the recoil spring...Springs work in both directions. ;)

Your post basically described the straight blowback design, which uses added slide mass and a heavy recoil spring to delay the breech opening. The short recoil system of the 1911 does it exactly the same way, except it "adds" to the slide's mass temproarily by locking the barrel to the slide, which negates the need for having to use a heavy slide. When the bullet exits, the pressure drops and the barrel starts to unlock. The slide, now free of its added burden, can move at full speed toward the frame's impact surface.

If the 1911 in its present form were to be converted to straight blowback by removing the locking lugs from the barrel, the recoil spring rating would likely have to be doubled...or greater... in order to keep the breech closed until the pressure dropped to a safe level.

[flcracker]

Wow, 1911Tuner - you have my head spinning in amazement that I can actually follow most of the physics you're talking about!

However, I'm coming at this from a very different approach - just trying to keep a "shooter" shooting, as opposed to precise match-fitting of the barrel and I'd like a little straightforward advice if you don't mind, Sir.

I have two Argentine pistols that I just acquired (see posts in the "foreign contracts" forum) - both were purchased from guys who had shot them some, but not much, after they had bought them used. Both of the barrels are pretty well worn, but they are the original barrels. So it has been suggested to me that I should maybe shoot them a little as-is to check functionality (they pass the non-firing function tests), but to install new barrels for general shooting and save the originals for collector's sake.

If I go with a Wilson "drop-in" barrel/bushing kit, and the stock-equivalent barrel link, am I likely to find myself wishing that I had just gone ahead and paid someone to do it right, or is the amount of fitting expected to be relatively minor and confidence-building for my 1911 skills? I understand that I will need to check the lug and hood enagement, as well as bushing-to-slide fit, but is this relatively straightforward? (Kuhnhausen's book is on the way)

Also, I know this is probably a dumb question, but should I plan on having the headspace checked after installing the "drop-in" barrel?

I appreciate your tolerance with me for these basic questions, but the advice on these forums has never failed me yet, and I'm just looking to decide whether my time is worth more than the aggravation I'm facing, and if I'd be better off just paying a 'smith to do it. Thanks.

flcracker

[shoe1966]

I am by no means in the same league as 1911Turner.

I have installed a few Wilson "drop ins". All that I have used have been pretty much drop in, you may need to take some of the hood both in length and width. If you can work a file and take your time, file a little and check you should not have any problems. Check the lug engagement both top and bottom, check that the link is not trapping by putting the slide stop through the link (with the slide off the frame) push it back against the back of the lugs and there should be a little side to side movement of the link. And when ever you put a new barrel in check the headspace.

Shoe

[1911Tuner]

Howdy FLcracker,

Actually...on any pistol of unknown history and as old as the Argentine Colt...
I'd do a headspace check before firing it with the OEM barrel. You'd be shocked at the new in box factory guns that almost fail the NO-GO test...
and some actually do.

Always check the headspace on a replacement barrel. The fingers that you save might be yours.

You can make a poor man's gauge by using a resized or unfired empty case
and a set of ingition feeler gauges...the little ones. Measure the case and use the largest gauge that will slip between the case and the breechface
with just a little drag. Add the thickness of the gauge to the case length, and add another .001 inch just to be on the safe side. It won't be as precise as a real gauge, but it'll be close. If the total adds up to more than .920 inch...proceed with all due caution.

[John]

Almost there, boss. The barrel doesn't initiate the slide's movement. The thrust vector between the slide and bullet does that. The slide pulls the barrel backward. If the barrel drove the slide, the lug contact areas would be reversed. Rear of the barrel lugs to front of the slide lugs.

Johnny, this is the part that puzzles me. Since the bullet is inside the barrel, I was expecting the barrel to start moving backwards, pulling the slide along with it. How can the bullet affect the slide? I mean, what is actually pulling/pushing the slide back? I was under the impression that the force which pushes the bullet out, (or rather the equal and opposite force to the one pushing the bullet out) was pushing the barrel back, which in turn pushed the slide back. If that is not what happens, what initiates the slide's movement, so that it pulls the barrel along?

[1911Tuner]

Johnny, this is the part that puzzles me. Since the bullet is inside the barrel, I was expecting the barrel to start moving backwards, pulling the slide along with it. How can the bullet affect the slide? I mean, what is actually pulling/pushing the slide back? I was under the impression that the force which pushes the bullet out, (or rather the equal and opposite force to the one pushing the bullet out) was pushing the barrel back, which in turn pushed the slide back. If that is not what happens, what initiates the slide's movement, so that it pulls the barrel along?

The same pressure in the chamber that drives the bullet forward drives the slide backward. If this weren't the case, the straight blowback action couldn't work at all. The slide is nothing more than a breechblock...a bolt. The breechface is often referred to as the thrust face, because the force vector thrusts against it with the same power that it drives the bullet.

>>>The Colt/Browning short recoil system works exactly the same way as a straight blowback design. It just uses a different system to delay the breech opening.<<<


Hmmmm...Lemme try this from a little different angle. Let's build an imaginary gun.

The slide is welded to the frame, and it has a channel in it that will allow the barrel to slip in and out of the slide freely. A slip-fit barrel within the slide.
The barrel has no locking lugs or link, and isn't mechanically tied to anything.
Aside from that, it's the same as any other .45 caliber barrel on the inside.

Imagine that you slid the barrel out of the slide, chambered a round, slipped it back in, and fired the round. Would the barrel slam backward into the breechface...or would it be launched along with the bullet? Remember how tight the bullet is when it's in the barrel...

When the 1911 goes bang, the lugs engage, and the slide drags the barrel backward as the bullet is in transit. Just shy of .10 inch (nominally) of rearward slide travel, the bullet exits, the barrel starts to unlock, and the slide continues via the momentum that it conserved during that first .10 inch of travel...while the bullet was still in the barrel.

[John]

I think we are getting somewhere. What you are saying is that the case is sealing against the chamber wall, and it is the case which is pushing the slide backwards, which then drugs the barrel along?

In other words, if there were no lugs to mesh on the top of the barrel, the slide would move back alone? Of course, that means disaster, since the pressure in the barrel is still high, but is that how it works?

[1911Tuner]

I think we are getting somewhere. What you are saying is that the case is sealing against the chamber wall, and it is the case which is pushing the slide backwards, which then drugs the barrel along?

In other words, if there were no lugs to mesh on the top of the barrel, the slide would move back alone? Of course, that means disaster, since the pressure in the barrel is still high, but is that how it works?

Bingo!

I've had people argue that, once the case is sealed under pressure, that it can't move backward...but that's absurd. If that were true, excessive headspace wouldn't be a safety concern. Excessive headspace allows the case to back out of the chamber when the force drives the bolt away from the barrel/breech area. The case backs out and becomes unsupported in the thin area forward of the webbing...and ruptures. Essentially, it causes the breech to partially open...and that ain't good.

Think a little deeper. If the barrel moved backward and drove the slide, the locking lug contact would have to be reversed, and the rear faces of the barrel lugs would bear against the front faces of the slide's lugs.

[John]

Exactly, that's what draw my attention to that. Also, my initial thinking is flawed because the barrel is in equilibrium, while the bullet is inside it. Pressure is directed at both ends, so it doesn't move itself. but of course, the case CAN move, as the bullet can. And the case would move, if it was not for the breechface, which is right behind it. So the case pushes on the breechface, which means it pushes on the slide, which in turn pulls back the barrel.

Thank you Johnny, now it makes sense.

[1911Tuner]

Exactly, that's what draw my attention to that. Also, my initial thinking is flawed because the barrel is in equilibrium, while the bullet is inside it. Pressure is directed at both ends, so it doesn't move itself. but of course, the case CAN move, as the bullet can. And the case would move, if it was not for the breechface, which is right behind it. So the case pushes on the breechface, which means it pushes on the slide, which in turn pulls back the barrel.

Thank you Johnny, now it makes sense.

YES! YES! YES! Another light goes on!

John, you'd really be shocked at the number of experienced people who don't understand how the gun functions...including some experienced pistolsmiths.
One in particular who claims to build the finest 1911 that the world has ever seen...but I ain't namin' names. Wichaka knows... :D Hard to soar like an eagle(<---CLEW! CLEW!) when the turkeys keep clippin' your wings...and he's clipped a lotta wings.

[John]

LoL, I guess it is not that easy, isn't it?

Now that we have established how the whole thing works, another issue. Please correct me if I am wrong somewhere.

As we established, the slide is pushed back by the case. So in reality, it is a good thing if the case touches the slide when it is in the chamber, I guess you call that headspacing, in other words the case should not be allowed to move to the rear, at least in an ideal situation. Correct so far?

Now, since it is the slide which pulls the barrel to the rear, why on earth do people get so crazy, about the hood touching the breechface, when the pistol is in lock? I've heard that if it is not touching the breechface, the felt recoil increases. According to the discussion we just had, this is BS.

Another thing. How are the two touching surfaces at the left and the right of the chamber supposed to be matted? I mean obviously the first thing is to make sure that the lugs are matted properly, but that might require some trimming of these areas, in addition to the hood. Am I right? How much can you trim there? And do you trim the slide or the barrel.

[1911Tuner]

LoL, I guess it is not that easy, isn't it?

Now that we have established how the whole thing works, another issue. Please correct me if I am wrong somewhere.

As we established, the slide is pushed back by the case. So in reality, it is a good thing if the case touches the slide when it is in the chamber, I guess you call that headspacing, in other words the case should not be allowed to move to the rear, at least in an ideal situation. Correct so far?

Now, since it is the slide which pulls the barrel to the rear, why on earth do people get so crazy, about the hood touching the breechface, when the pistol is in lock? I've heard that if it is not touching the breechface, the felt recoil increases. According to the discussion we just had, this is BS.

Another thing. How are the two touching surfaces at the left and the right of the chamber supposed to be matted? I mean obviously the first thing is to make sure that the lugs are matted properly, but that might require some trimming of these areas, in addition to the hood. Am I right? How much can you trim there? And do you trim the slide or the barrel.

Correct. When the case moves to the rear, it's moving toward losing chamber support. Re-read the differences between static headspace and working, or live headspace. Headspace can be excessive in two different ways. One is dangerous, and one is not...assuming all the exxcess is in one direction or the other. Most guns that do have loose headspace more or less divide the static dimension somewhere in the middle unless it's due to lug setback. Then it's all in the dangerous direction.
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Hood touching breechface:

When the hood is closely fitted to the breechface, the slide pushes the barrel forward to its limit within the slide, and engages whichever lug or lugs that will horizontally engage...eliminating the fore and aft slack between barrel and slide...which eliminates slap-seating...which prolongs the life of the lugs.
Imagine pushing two hammer heads together with 500 foot pounds of force.
Now, imagine slamming them together from a foot apart with the same force.
in which case are the two heads going to deform faster?

Now...same two hammer heads slammed together on center, and slaming them together on a 50% offset. This illustrates the importance of full vertical depth of engagement. See it?

Sides of the hood closely fitted:

Accuracy doesn't come from any one fit or dimension. Many things stack up to create it by working together..and consistency is the key. When the sides of the hood have a lot of clearance, the barrel can shift a little from side to side as it cams up...which alters the angle of the chambering cartridge. A close fit eliminates a little inconsistency. Doesn't mean a lot, but it does mean something...and many little "somethings" add up to paint the larger picture.

The other aspect of the close fit in that area is that it helps to limit the amount of torque that the barrel undergoes when the bullet hits the rifling...which imposes high rotational forces on the barrel. Again...it doesn't control it completely, but rather eliminates a lot of it..which in turn adds to the accuracy of the gun.

The sides of the hood shouldn't be making actual contact. No such thing as a free lunch. Contact would impose added drag as the barrel cams up, and a little dirt or even heat could contribute to causing a failure to go to battery.
For maximum accuracy, about .001 inch per side is as close as it should be. For reliability, .005 inch. .003 inch strikes a workable medium...but only for a game gun. Carry guns should be set at .005 per side.

Likewise, a tightly fit hood to breechface is a good thing for accuracy and durability, but the drawbacks are the same. Too tight, and the gun fails to go to battery unless kept clean. I've seen bullseye shooters field-strip and clean the areas as early as every 35-40 rounds because of malfunctions.
For the really serious ones who had their static headspace set below minimum and trimmed their brass to fit within .001 inch...they also use a dry brush in the chamber to get rid of the carbon build-up at the chamber shoulder...but these guys are chasing one-inch groups at 50 yards...and malfunction alibis are allowed.

So, one has to determine what...and under what conditions...the gun is being built or tuned for. To strike the best compromise between accuracy and reliability, the clearances need to be a little looser. Not "rattletrap loose", but enough to allow for a reasonable amount of dirt and fouling. Also, the less able you are to maintain the gun, the looser it needs to be. If you can strip and clean it every day...even if it's just a quick wipe-down and light lubrication, you can get away with tighter clearances. If you can only manage once a week, more clearanceis needed. If you're under fire in the trenches at Belleau Wood...best go with an ordnance-spec gun.

I've found that...under non-wartime conditions....003 inch of clearance at the hood and slide...and .005 inch on the sides works well as long as I take reasonable pains to clean and oil the gun. Stip and wipe once a month. A drop of oil in the rails with the slide locked back, and allowing the oil to run
down for a minute or so...and detail-stripping to get the dust and lint out every 3 months is a good schedule. If I had to grab one pistol and run..I'd pick up the 1919 Colt, the 1945 Rand or one of the Norincos...but probably the '43 GI Colt that I rebuilt this year and carry a lot. It has a well-fitted Kart QUick'n'Easy fit...with .003 at the breechface and .006 at the sides and two lugs bearing the load. Static headspace is .905 inch. The only play between the slide and frame is when the pistol is dead dry. A little oil, and there isn't any. It's more accurate than I can prove without a sandbag rest, and it never malfunctions. Not even with my funky reloads...dry or lubed...cold or hot. Yeah. I wouldn't hesitate to bet my life on that one.

[John]

Hmmm, I imagine I didn't clarify myself enough. I was not talking about the sides of the hood of the barrel, but at the two areas at 3 and 9 o'clock on the rear of the chamber, which touch ledges inside the slide.

[1911Tuner]

Hmmm, I imagine I didn't clarify myself enough. I was not talking about the sides of the hood of the barrel, but at the two areas at 3 and 9 o'clock on the rear of the chamber, which touch ledges inside the slide.


Ah! Sorry John.

Those areas should have a little clearance with the slide and the only contact should be with the hood face. Otherwise the chamber face will get peened by the slide. The clearance is correctly done on the slightest forward angle top to bottom. About 2 degrees or a little less, starting with a couple thousandths clearance in the corners of the hood, and increasing toward the bottom. The angle isn't really critical as long as there's enough clearance.

[John]

Johnny,

These are the areas I am talking about:

http://img.photobucket.com/albums/v323/sv1cec/Pict1722.jpg

Not at the sides of the hood, at the sides of the barrel.

[1911Tuner]

Yep...that area should have just a tiny bit of clearance with the slide. I'm talkin' maybe .003 inch at the widest points.

[John]

And where do you file? The barrel or the slide? I assume the barrel.

[1911Tuner]

And where do you file? The barrel or the slide? I assume the barrel.

Yep...barrel. The reason for the slight angle is because the barrel locks into battery on an angle. If it moved through the arc at the rear, and both barrel and slide were square...the lower edge of the barrel ramp would crash with the slide.


See? It's the little things that getcha. ;)

[auto45]

My old Colt bbl had contact where John points with the arrows, nothing on the bbl hood and breechface.

The new Springfield bbl has contact with bbl hood and breechface and nothing on the area shown with the arrows.

Both "drop in bbls". :)

[1911Tuner]

My old Colt bbl had contact where John points with the arrows, nothing on the bbl hood and breechface.

The new Springfield bbl has contact with bbl hood and breechface and nothing on the area shown with the arrows.

Both "drop in bbls". :)


I Betcha if you hadda slipped about 3 thicknesses of paper between the hood and the slide and let it go to battery, the barrel wouldn't have made that contact I betcha... ;)

[auto45]

I don't doubt it.

As well as you explain it, I don't think this bbl fitting "thing" is that easy, if you want a long lasting, accurate 1911. ;)

[gottripletsNC]

ok so now I understand the process of slide, barrel movement in recoil, which by reading between Garrett, Tuner and the Boss was quite easy to understand now, now here's my stab at understand the bottom side of the barrel, and please clarify this too Johnny, cause so far this thread has been the most informative in the year I've been on here.

when recoil starts the lugs hold the barrel to the slide initially to prevent the barrel from going forward which protect the link. But after a short movement backward, the sudden forward motion is thwarted because the excessive barrel pressure is relieved, and the short backward movement reaches the link's travel extent and starts to pull the barrel down to disengage the lugs, but with proper recoil spring and proper tolerances in clearance there is little force exerted on the link?

Secondly this is where link size can be dangerous...
Too long at it keeps barrel disengagement too long, causing damage to the link, or in non ramped barrels damage to the lower seat from too much rearward travel, or even to tight to bring the gun to full battery.
Too short and it disengages too quick allowing excessive recoil gases (possibly even dangerous blowback to the operator) and too much force on the link from the round not fully exiting the barrel, and not allowing the excess to be blown off.
Which for lack of better terms screws up the whole timing of the gun?

Am I way off base or getting there O Master of the gun...

[1911Tuner]

I don't doubt it.

As well as you explain it, I don't think this bbl fitting "thing" is that easy, if you want a long lasting, accurate 1911. ;)

Nahhhh. It sounds like it's tougher'n it really is. If you'd see it done once, and do it once under guidance, you'd be like: "Is THAT all there is to it???"

Gottriplets...whew!...I'm gonna try to formulate an answer...but it might be simpler if ya just called me. You're pretty close, but I'm not too sure about your descriptions and may be readin'em wrong.

I'll take a quick stab at one though...

A link that's too long for the gun's specs delays barrel unlock...which isn't always a bad thing...but it also delays the linkdown and drop to the bed...which can be a very bad thing if the barrel doesn't drop far enough or fast enough to get clear of the slide as it passes over the top.

[gottripletsNC]

Ok lemme go from trigger pull to reload of next round as I understand it and you tell me if this meets proper function thus helping me to understand barrel fit as well. Specific distances I don't know but will one day... ;)

Gun is fired, initial recoil shoves the slide back and pulls the barrel back with it for a short distance. While moving backwards, the bullet is propelled forward by the expanding gases of the gunpowder. Preferably the gases have expelled by the time linkdown begins to prevent gases from being blown out of the breech back at me. After a short distance, the link has reached its limit of travel and the barrel begins to drop by the linkdown, however, the gases have been expelled, and the linkdown is under the pressure of strictly recoil at this time as found in the inertia of the slide, not from the blast of gunpowder(thus preventing undo stress on the link). The barrel drops out of the lugs and the slide continues to travel back while the barrel stops on the frame that the barrel is now sitting on with it's bottom lug. The extractor pulls the casing out of the barrel, when the casing strikes the ejector at full recoil by the extractor pulling the right side as the ejector pushes the left. The recoil spring then pushes the slide back into battery, the next round is at the top of the magazine and the bottom of the slide pushes the top of the round forward up the ramp into the barrel. As the slide contacts the hood of the barrel the barrel is pushed forward, the link can't compress so it rotates upward pushing the barrel back up into the lugs for the next round.

short link disengages too quickly, and can cause the barrel to sit too low not allowing good lug lock up, and can cause high primer strike??? even allow blowback of gases from premature linkdown?

Long link can put too tight of a lug lock up, and also too long of a time for lug disengagement, and if the lower strikes before the uppers can disengage, can be ugly? Not to mention it doesn't allow the barrel to rest on the lower lug when the barrel is not in battery?

Am I getting worse or do I understand it now?

fingers crossed :butthead:

[garrettwc]

Hard to soar like an eagle
LMAO. I would have gotten that one without the clew. ;)

Yeah I forgot about the recoil spring and the link. For some reason I was thinking that the length of the link would allow excessive forward travel and the barrel would extend out the front of the frame but that wouldn't be possible.

Tripletts, this one has been a real schooling for me too. I'm going to print it out and put it in the ol' notebook.

[gottripletsNC]

when Tuner tells me I am right, then i will consider it schooling, if he tells me I'm wrong then I'm still confused as ever...

We'll see if I got schooled or not, can't get any dumber thats for sure...
ROFLMAO

[John]

Long link can put too tight of a lug lock up, and also too long of a time for lug disengagement, and if the lower strikes before the uppers can disengage, can be ugly? Not to mention it doesn't allow the barrel to rest on the lower lug when the barrel is not in battery?

The only inaccuracy I found in your description, is that you mention that when the barrel is unlocked and cam down, it rests on the lower lug. When the barrel is unlocked it's resting on the frame bed, with the barrel legs touching the vertical surface right in front of the bed. When the barrel starts going forward, as the link pushes it up, at some time, the link stops acting and the barrel lower lug starts riding on top of the slide stop pin. At full lock, it is the slide stop pin, and the lower barrel lug (the barrel feet) that are pushing the barrel up, so that the upper barrel lugs mesh with the slide lugs.

[1911Tuner]

You're homin' in on it gottriplets! John's post is correct. The barrel is correctly cammed upward by the slidestop pin bearing on the lower lug....correctly. Not all guns are correctly built though...and riding the link and standing on the link does happen, though it's not seen as often as it used to be.

I've done a copy on your last post. Gonna paste it to a notepad and separate the text with bracketed answers that'll fine-tune your ideas,
and cut/paste the whole thing onto a reply.

One point to keep in mind is that the beginning of the barrel unlock sequence
at .100 inch of slide travel allows for a little adjustment. That figure is nominal...for ordnance-spec pistols. it can range from .090 to .110 inch, and
accuracy oriented smiths will try to delay that for as long as possible and still allow the barrel to drop in time to get out of the slide's way. The limit is in the .120-.125 inch range. This covers ammo variations and keeps the barrel from starting to tilt until the bullet has had time to exit. It's a small point that wrings the nth degree of accuracy from the gun, since the barrel can move only a tiny amount when the bullet is still present, and pressures are high...and if it tries to unlock with pressures high can result in damaged lugs and a stretched link...along with the possibility of lower lug separation... since the lugs are baring against one another under some 20,000 psi. Trying to pull them apart is akin to clamping a flat piece of steel in a vise and yanking it out with an attached chain. Delaying the beginning of the unlock sequence is pretty much making sure that doesn't happen, and it's to protect the precisely fitted lugs more than anything else. .090 is a bit early, but will do as long as standard-pressure ammo with an acceptable pressure spike time is used. Slower powder used with some +P ammo may throw things off
enough with a .090 unlock point to do some bad things. Faster powders peak quickly and fall off quickly after the peak. A .100 or .110 inch timing point
works better all the way around with varying ammo.

Stand by...Reply on the way.

[John]

John's post is correct.

That's a start!!!

[gottripletsNC]

The only inaccuracy I found in your description, is that you mention that when the barrel is unlocked and cam down, it rests on the lower lug. When the barrel is unlocked it's resting on the frame bed, with the barrel legs touching the vertical surface right in front of the bed. When the barrel starts going forward, as the link pushes it up, at some time, the link stops acting and the barrel lower lug starts riding on top of the slide stop pin. At full lock, it is the slide stop pin, and the lower barrel lug (the barrel feet) that are pushing the barrel up, so that the upper barrel lugs mesh with the slide lugs.

AHHHH!!!!!!!!!!!

that was the one thing I was still confused about, now I see

thank you sir




And Tuner thank you, from the barrel fitting clinic I was able to finally understand the barrel thing, now gotta fully understand the disconnector, sear, hammer thing, once I get that, then I'll worry about numbers, then maybe just maybe I can say that know a little something.

[1911Tuner]

Put on the coffee. :p

re: Shot in the dark by gottriplets
--------------------------------------------------------------------------------



Gun is fired, initial recoil shoves the slide back and pulls the barrel back with it for a short distance. While moving backwards, the bullet is propelled forward by the expanding gases of the gunpowder. Preferably the gases have expelled by the time linkdown begins to prevent gases from being blown out of the breech back at me. After a short distance, the link has reached its limit of travel and the barrel begins to drop by the linkdown, however, the gases have been expelled, and the linkdown is under the pressure of strictly recoil at this time as found in the inertia of the slide, not from the blast of gunpowder(thus preventing undo stress on the link). The barrel drops out of the lugs and the slide continues to travel back while the barrel stops on the frame that the barrel is now sitting on with it's bottom lug.

{ On some older pistols, the lower lug feet were dimensioned to stand the barrel just off the frame bed. Rarely seen any more on factory fit barrels, and doesn't seem to cause problems unless the bottom of the barrel hits the frame bed before the rear of the lower lug stops on the vertical impact surface. Correctly timed, the barrel's rearward movement is stopped on the VIS
just before settling down into the bed. Otherwise, the link is still pulling the barrel downward at an angle while the barrel is moving backward in a straight line. Lug separation occurs eventually, depending on how mcuh the barrel has to move rearward after hitting the bed.
Some guns take a long time. In others the separation can occur within a few thousand rounds. }



The extractor pulls the casing out of the barrel, when the casing strikes the ejector at full recoil by the extractor pulling the right side as the ejector pushes the left. The recoil spring then pushes the slide back into battery, the next round is at the top of the magazine and the bottom of the slide pushes the top of the round forward up the ramp into the barrel. As the slide contacts the hood of the barrel the barrel is pushed forward, the link can't compress so it rotates upward pushing the barrel back up into the lugs for the next round.

{Again...Correctly fitted, the link doesn't pivot the barrel upward. It's sole function is to unlock the barrel from the slide. Riding the link into battery isn't as bad as it sounds as long as: The barrel doesn't actually lock on the link, and the barrel doesn't ride the link high before the final approach into battery...which can be a contributing factor in excessive stem bind...aka 3-point jam...and even pushing the barrel up into the slide too early for the lugs to mesh properly. In early barrel rise, the length of the hood can also be a factor in timing the rise of the barrel too early...but the generous clearances between slots and lugs usually put the blame on either an overlength link, or the incorrect specs on the lower lug's geometry.}

short link disengages too quickly, and can cause the barrel to sit too low not allowing good lug lock up, and can cause high primer strike??? even allow blowback of gases from premature linkdown?

{{ Again...The length of the link doesn't control the vertical lockup unless things are badly out of spec. The short link won't work with a correctly dimensioned lower lug because it puts the slidestop pin into a bind between the bottom of the hole and the forward radius of the lug.
Clearancing the link a little at the bottom of the hole used to be a quick fix for this, provided the barrel locked on the lug and pin interaction..but the hole elongation is limited to .003 inch. It was done mainly before the wide availability of varying link on-center lengths, and small adjustments were necessary to keep the barrel from riding the link "around the corner."
It's now considered to be not much more than an expedient repair, and it's always better to use the correct link whenever possible...or...in cetain examples...to use a .003 inch longer link and elongate the slidestop pinhole at the TOP...which doesn't affect linkdown timing at all, and doesn't cause the link to slap the pin as it reaches the limit of its arc.

The link's on-center length affects linkdown timing. A too-short link can also prevent complete linkdown of the barrel, and the result is often the same as the vertical impact surface being located too far forward...and so can the long link...though the damage incurred by the long link is usually worse because it lets the rear face of the lower lug to hit the VIS while the lugs are still engaged...and the crash is solid between the frame, lower lug, and locking lugs. With the short link, the crash is between the link, upper lugs, and the slidestop crosspin.}}

Long link can put too tight of a lug lock up, and also too long of a time for lug disengagement, and if the lower strikes before the uppers can disengage, can be ugly?

{{{ Yes...IF the barrel locks on the link. If the lower lug geometry is wrong, the long link can allow correct vertical lock (on the pin and lug) and still be too long for correct linkdown timing.
This condtition is pretty rare, and usually only seen in guns that are so far out of spec in other places that they rewquire a complete rebuild in order to correct the problems...and sometimes can't BE corrected. Usually seen in, but not limited to cheap knock-offs, I've seen it in Colts and Springfields...and lately in a few Norincos...but not often .}}}

Not to mention it doesn't allow the barrel to rest on the lower lug when the barrel is not in battery?

{{{{ Again, having the barrel rest on the lower lug feet is something that we haven't seen much of in a production gun since the specs were modified for the 1911A1 governement contract pistols. When you do happen to see it, either the gun was carefully built by somebody who knows about how the early pistols were built...or it's purely a fluke. It was deemed unnecessary by the Army Ordnance engineers because it was easier and faster to
correctly spec the VIS and lower lug location than to hand-fit a barrel with long feet. This dimensioning was done with standard gauges and the process of select-fitting...which is pretty much the way production guns are assembled today...minus the close-tolerance gauges, apparently. You can thank..or blame...those redesigned specs for the drop-in aftermarket
that sells so many millions of dollars worth of parts to the public...many of which still require some fitting. Sometimes they require a lot of fitting. Even whenexamining an older gun, you won't find that particular fit very often unless you happen to get lucky and find a commercial
pre-A1 Colt. The reason is simply that so many of the GI pistols were refitted with later barrels that adhered to the redesigned specs. I have a 1919 Colt that wears the original barrel..which is in pristine condition. A strip of crepe paper will just slip out of the bed area without tearing with the barrel pushed down and back firmly. The gun is tight and pretty much rattle-free...and if I take my time at 50 yards, I can shoot one-handed (Bullseye -style) using a center hold, and ring a 10X16-inch steel plate with boring regularity...with the issue sights and my issue eyes. The gun will function perfectly with hollowpoints, 225-grain truncated cones, and 200-grain SWCs fed from the original "Hardball Only" magazine. Anyone who is within driving distance is invited to come see my old girl. I'm right proud of her.

This is the way they used to be...and we won't see their likes again in a production gun...and in very few hand-built customs. }}}}

Am I getting worse or do I understand it now?

***Yep! You have learned well, grasshopper!***

[Herknav]

Wow! Tuner, I don't think you've ever opened your mouth when I didn't learn something. Please put me down for copy #1 of your book when it comes out. :D

Seriously, have you ever thought about "Tuner's Oracle of the 1911"?

Cheers,
Herknav

[1911Tuner]

Wow! Tuner, I don't think you've ever opened your mouth when I didn't learn something. Please put me down for copy #1 of your book when it comes out. :D

Seriously, have you ever thought about "Tuner's Oracle of the 1911"?

Cheers,
Herknav

AHhhhh...Thanks for the good words, Herknav.

The main thing that keeps me from entertaining the book issue is that the publisher will probably wanna put my picture in it somewhere...and I hate cameras worse than cockroaches. :D

Honestly, I'd probably catch flak from many corners on the information in a book like that. The problem with the new-age viewpoint on 1911 is that, the buying public has demanded tight pistols capable of match accuracy, along with so many custom bling-bling for so long...that they think that's the way it's supposed to be. That, and the fact that the gun allows those kind of modifications and remain functional...for the most part anyway...that there's no way to convince'em otherwise. Most of the customs these days are really not much different than the old National Match guns were...just prettier.
That isn't a problem in and of itself, and there are some gifted smiths out there who do'em up right...but that kind of setup is essentially a variation of
what the gun was designed to be...and of the role that it was intended to fill.

The myth of the loose, inaccurate and unreliable 1911 came from conscripts who either handled some badly worn or abused guns and only had "familiarization" with the gun instead of a real training program...or both. I've fired old guns that belonged to owners who stated matter-of-factly: "Can't hit the broad side of a barn with these old "Army .45s" 'cause they just ain't any good." More often than not, it turns out that the guns will do just fine, even with some pretty bad wear. They're amazed when I'm able to bounce a beer can over and over at 25 paces with their "innacurate rattletraps." Even had one guy to get defensive, since I had used trick shooting to "suggest" that he couldn't shoot for sour apples. I bought his pistol that very day. A pretty nice Ithaca, actually...I don't have it any more.
My bad...

[John]

Please put me down for copy #1 of your book when it comes out.

Sorry Sir, copy No1 has already been promised!

The main thing that keeps me from entertaining the book issue is that the publisher will probably wanna put my picture in it somewhere...and I hate cameras worse than cockroaches.

Don't worry about that Johhny, you can use my picture instead!

[1911Tuner]

Sorry Sir, copy No1 has already been promised!



Don't worry about that Johhny, you can use my picture instead!


Hey...As long as they spell my name right and gimme the money, I don't care if they put Donald Duck's picture on it. :D

[gottripletsNC]

...the barrel's rearward movement is stopped on the VIS
just before settling down into the bed. Otherwise, the link is still pulling the barrel downward at an angle while the barrel is moving backward in a straight line...
I understand that now, but what about guns with fully ramped barrels?

...having the barrel rest on the lower lug feet is something that we haven't seen much of in a production gun since the specs were modified for the 1911A1 governement contract pistols. When you do happen to see it, either the gun was carefully built by somebody who knows about how the early pistols were built...or it's purely a fluke...
so I am right in assuming that this is the ideal way for the barrel to sit, but requires too much attention to get it so they its not really done anymore?
and the real thing holding the barrel in place is upper lug engagment and proper link length with the proper arc to encourage upper lug engagement?

The rest I think I understand and what I meant is what you said, not what I said, told ya I can't write what i mean most of the time.

[gottripletsNC]

whilst you two are arguing about book number one, Johnny can be autographing number 2 for me, and I'll just ride up the road apiece, 2 1/2 hours roughly and pick up my copy while you are arguing or waiting on overseas shipping....

[Herknav]

Here's my rebuttal:

Tuner: Put a picture of a nice Gov't Model on the cover and call it done. As to your second point, everything goes in cycles. In another 20 years, loose guns might be "in" again, and you could be the Godfather. Whaddaya think?

El Comandante: Pardon me. I didn't realize this had been discussed before. I really don't care what copy I get, so long as I get A copy.

gottripletsNC: That would be cool, but I'd have to work at Ft Bragg Army Airfield. Thanks, but I'll keep my view of Denali (Mt McKinley for those in the CONUS.)

Cheers,
Herknav

[1911Tuner]

Questions:

the barrel's rearward movement is stopped on the VIS...

I understand that now, but what about guns with fully ramped barrels?

{Same deal, except the bed is lower and squarer.(Is squarer a word?) }



so I am right in assuming that this is the ideal way for the barrel to sit, but requires too much attention to get it so they its not really done anymore?
and the real thing holding the barrel in place is upper lug engagment and proper link length with the proper arc to encourage upper lug engagement?

{ Correct...and incorrect. The link isn't supposed to actually lock the barrel vertically, though when it's overcentered and in compression against the rear curve of the feet via the slidestop pin, it gets a little "boost" for a couple minutes of a degree. Correct vertical engagement is controlled by the dimensions between the slidestop pin location , lower lug dimensions and geometry, and the slide's installed height. }

The rest I think I understand and what I meant is what you said, not what I said, told ya I can't write what i mean most of the time.

{{ Tell me...have you been hearing these voices for very long? }} :p

[gottripletsNC]

gottripletsNC: That would be cool, but I'd have to work at Ft Bragg Army Airfield. Thanks, but I'll keep my view of Denali (Mt McKinley for those in the CONUS.)

Cheers,
Herknav

I can be on Ft Bragg in less than 30 minutes...

Go through post every morning on my way to work


{{ Tell me...have you been hearing these voices for very long? }}

how did you know about those voices?
huh wha.. who's there?
hey leave me al....
sorry guys lost my track, heard somethin


Correct vertical engagement is controlled by the dimensions between the slidestop pin location , lower lug dimensions and geometry, and the slide's installed height.

ok, i'm wid ya now Tuner
Great day in the morning, I actually understand how the thing works now

[John]

El Comandante: Pardon me. I didn't realize this had been discussed before. I really don't care what copy I get, so long as I get A copy.

I agree with you Sir, no question there. Actually I think that Johnny will have too many more important people to devote his No 1 copy than me. I was just kidding.

[1911Tuner]

gottriplets sez:

>>ok, i'm wid ya now Tuner
Great day in the morning, I actually understand how the thing works now.<<
*******************

I just love it when the light goes on! You can almost hear'em.

What's more important is that you now know what to look for that's wrong when you're considerin' a buy...and there are a lot of'em out there that are wrong. More than a barely discernible amount of downward play of the barrel
hood when in battery (.003 inch) and you apply pressure with your thumb...An obviously long link that stands the barrel off the lower lug(.003 inch, and ideally none)...Excessive endplay between barrel and slide with the top-end off the gun and the barrel in full vertical engagement( .005-.006 inch maximum)...Rolled, peened, or otherwise deformed barrel locking lugs...even if it's only one lug...Obviously deformed or battered areas on the lower lug feet and rear radius and at the rear face...All these things are tellin' ya to leave it on the table and keep lookin'.

I try to get permission to use my field headspace set. If the gun goes to battery on the .910 and offers resistance on the .912, I'll buy the gun. If it goes on the .912, I'll still buy it if it won't go on the NO-GO and I can get the price down by about 50 bucks. If it almost goes on the .920, I leave it unless I can get a discount that'll cover 90% of the cost of a new barrel.

Insert the .920 NO-GO and let the slide close easily...and lightly bump the rear of the slide. Pull the slide back. If it's a little tight coming out of battery, the NO-GO almost went. Point that fact out to the seller. If he won't drop his price by 75 or 80 bucks...walk away.

Pull the slide rearward and look at the first lug's abutment face within the slide. Guide the slide forward slowly until you can see the barrel start to cam up. If the first barrel lug only covers about half of the available height of the slide lug...you may have a problem that only a hard-fit barrel can correct...or even swaging the rails and refitting the slide.

[garrettwc]

The problem with the new-age viewpoint on 1911 is that, the buying public has demanded tight pistols capable of match accuracy, along with so many custom bling-bling for so long...that they think that's the way it's supposed to be.

And then they carry a Glock because it's simply designed, durable, and reliable. :rolleyes:

This has to be one of life's great oxymorons. The things they all like about the Glock are the very things that made the 1911 great before so many lost souls started mucking with it.

[1911Tuner]

garrett...You just said a mouthful.

[AnthonyRSS]

About this book...

I'd be willin' to bet you could get $50 a copy, and thats without your John Hancock.

I'd give a hunnert for that one.

[Ken Grant]

Johnny,you could always rough out a book,send it to Capt. Dave Sample and let him edit it. :scared: :D :nono:

[OD*]

Now that's just mean man. ;)

[AnthonyRSS]

It would be less than a pamphlet then.

[1911Tuner]

Ken...ROFL...I really can't believe you said THAT! I can't get him up to speed on headspace, much less fittin' a lug-equalized match barrel. Wonder if he knows that some of'em have different lug and slot heights...and that Kart ain't one of'em...Hmmmm.

[Ken Grant]

Maybe I should not had said that,maybe I should have said T.J. instead! :D
He calls old USGI 1911's junk. :nono:

[1911Tuner]

Maybe I should not had said that,maybe I should have said T.J. instead! :D
He calls old USGI 1911's junk. :nono:

Flip a coin... :rolleyes:

[saltydog]

I think that I'm not gonna like the answer but I need to ask anyway...

On my 2nd 'Rinco, (bought slightly used), the headspace was exceptionally good, there was also signs of face battering much like the illustration on John's post #29. The battering wasn't so much as to chip the chrome plating but I figured that would occur in a short time. I suppose I could use some Simechrome to maybe 'shine' off some of the battering marks, but what would be a long-term fix?

Thanks,

salty.

[InTheBlack]

re the .003 ideal/minimal clearance between barrel hood and breechface...

Since the purpose of a small clearance is to help nudge the barrel forwards into upper lug engagement, could we not narrow a wide gap by a few thousands by painting on a coating of something elastomeric... like the Dip-It vinyl coating for tool handles?

Sure it would wear off, but for a target gun you could recoat it every time you clean it. And even if you eliminated the gap entirely, you wouldn't be getting metal-to-metal slamming, and dirt particles would imbed themselves into the coating instead of jamming up.

Why not create an elastomeric insert which would ensure the lugs were in contact? At least for target guns.

I love these tutorial discussions, but they always seem to fade into a lot of jokes & chatter, which makes following the important stuff harder to do.

Why not put a nylon insert in the frame under the barrel lower lug feet in order to make the barrel sit on the feet? The feet would squish down into the nylon and leave the barrel fully upwardly engaged. The length of the feet would be allowed a wide tolerence, easy to fit.

[InTheBlack]

Oh, another thing. When the barrel is pushed forwards by the bullet engaging the rifling: in a well-fitted gun, does the upper lug face make contact with the slide slot a fraction of a moment before the brass makes contact with the breechface? I get the impression it should.

[InTheBlack]

And yet another thought after reading the headspace sticky.

Why not "perfect" headspace by gluing a donut shaped shim on the breechface, around the firing pin hole? Metal or even modern synthetic material. You might not want the possibility of adhesive failure on a carry gun, but why not on a target gun? As long as the headspace without the shim isn't No Go, you still have a safe headspace.

[1911Tuner]

Whew! InTheBlack...I don't know where to start.

The breechface to barrel hood impact doesn't amount to much. If it did, there would be tens of thousands of 1911s out there with beat-up barrel hoods and breechfaces.

Polymer on the low lug...Would last about 25 trips into battery on a tightly-fitted barrel.

A doughnut "ring" on the breechface wouldn't do a thing for headspacing that's excessive in the forward direction...and it wouldn't let a round feed anyway. The 1911 is a controlled-feed weapon.

Question:

>Oh, another thing. When the barrel is pushed forwards by the bullet engaging the rifling: in a well-fitted gun, does the upper lug face make contact with the slide slot a fraction of a moment before the brass makes contact with the breechface? I get the impression it should.<

Uh...No. The breechface always makes contact with the cartridge rim first as it strips it from the magazine, well before the barrel is affected.

I might suggest a crash course in how the pistol functions and report back.

Luck!

[scooter]

Ive learned more from tuner than "ANYWHERE" else Ive gone to learn about the 1911 and its function.Go to the STI site and watch their little movie doohicky and you'll see what hes talking about.(this is meant in fun not to be dissin ya) but the "fixes" you suggested are like instead of puttin new shoes on the brakes in your car ya just tied a chain to an anchor and throw it out the winder.......http://forum.m1911.org/images/icons/icon15.gifhttp://forum.m1911.org/images/icons/icon15.gif

[John]

Why should you go to the STI site? That animation exists also right here, in the first page actually. Kindly donated by David Skinner himself to M1911.ORG.

[1911Tuner]

Except that...unless they've amended it...the function in STI's video is wrong.

Can anybody spot it? :D

Shhhh...Don't tell'em if ya know.

Yep. Still wrong in two aspects. One not really important...the other grossly so.

[John]

Well, the bullet is gone and the slide is still motionless! Is that it Master????

[1911Tuner]

Dang Commandante! Ya done nailed it! :D

Now...What's the other one?

[3jaw]

It looks to me like the barrel is motionless when the bullet is traveling down the bore and the upper slide and barrel lugs aren't locking together. Also, it looks like the first lug is doing all the work.

Is that it, Tuner???? ;)

Greg

[1911Tuner]

That may be a part of what's wrong too, 3jaw...I'll go look closer. The thing that's utterly wrong is that the bullet has exited and the slide still hasn't budged. If the bullet is gone before the slide moves...the slide WON'T move.

[Dr. Dickie]

The barrel should start its forward journey BEFORE that slide hits it, right? Doesn't the bullet hiting the top of the chamber begin to drive the barrel back forward and up?

[1911Tuner]

The barrel should start its forward journey BEFORE that slide hits it, right? Doesn't the bullet hiting the top of the chamber begin to drive the barrel back forward and up?

Not supposed to, Doc...at least not if the specs are correct. A little refresher in how the feeding phase works may help.

Consider that the cartridge enters the chamber at an angle after deflecting off the feed ramp. The bullet nose contacts the ramp somewhere above mid-point and high on the barrel throat...just below the corner...before the bullet nose hits the chamber roof. This is the point that the gun is in light stem bind, and the barrel is held against the frame bed. As the rround breaks over to horizontal, the friction applied to the roof of the chamber diminishes.

This is why the feed ramp angle is so critical at 31 degrees, with very little
wiggle room. If the angle is too shallow, the round enters the chamber too low in the barrel throat, it does push the barrel forward, which also allows the barrel to pivot up as the slide moves. If the angle is too steep, the bullet nose strikes the chamber roof too far back, and the side of the case is at a more acute angle against the corner at the barrel throat corner, where it becomes chamber floor...and is kinda like the proverbial square peg in the round hole. This creates an excessive stem bind condition known as "The 3-Point Jam." This is also why barrels with integral feed ramps often give trouble. The angle is usually too acute, and there's no transition. The cartridge goes from ramp straight to the breakover point without the benefit of the "flat" spot between feed ramp and barrel. This charactistic makes the
magazine timing/release point much more critical. If it's just a little late on the release, the round goes into hard stem bind and stops well short of battery. If the integral ramp is too shallow, the bullet nose doesn't have the
required resistance to remain under full control, and bounces around as it enters the chamber...often ahead of the extractor hook. Re-read "COntrolled Feed Principles" to get a little better understanding.

So...if the gun is within spec, the barrel is nailed down during the feeding phase, until the round has broken over to horizontal and is well in the chamber. After that occurs, the barrel is free to move without causing a problem. If the hood is closely fitted to the breechface, the slide pushes it into lockup. If the hood has clearance, it pushes it nearly into battery, and the slide's locking lugs pick up the barrel lugs and finish pulling it in. In this setup, the barrel isn't fully engaged horizontally, like it would be if hood to breechface is a tight fit. Engagement occurs under firing pressure after the slack between the lugs has been taken up. (Barrel driven forward/slide driven rearward.)

Many people...including some experienced pistolsmiths...mistakenly believe that the breech is locked when it goes into battery, but it's not....not in the strict sense of "Locked Breech." It locks when the gun fires.

[Dr. Dickie]

Okay, last try. The slide travels so far back, that the disconnetor could flip up (it goes into the breechface cut-out). It wouldn't because the trigger is still depressed, but I do not think the disconnector goes that far forward (at work, no gun to consult).
If that isn't it, I quit.
(thanks for the correction Tuner)

[1911Tuner]

Howdy Doc,

The disconnect moves on two axes...Up/Down and In/Out. Study the square hole in it.

When the slide is forward and the trigger is free, the center leaf of the sear spring pushes the disconnect forward and up. It resets into the crescent-shaped cut in the slide center rail. This positions it between the trigger stirrup and the sear...or in the "Connected" position.

When the slide moves rearward, the disconnect is pushed downward, and
below the sear feet. Rearward pressure on the trigger rotates it backward through a short arc, placing it under the sear feet...which captures it until the trigger is released. When the trigger is released, the disconnect is free to reset into the connected position.

The fact that the slide uncovers the disconnect when fully rearward is incidental. Even if the disconnect could reset, when the slide moves forward again, it cams back down into the disconnected position.

[InTheBlack]

>>>
The breechface always makes contact with the cartridge rim first as it strips it from the magazine, well before the barrel is affected.
>>>

Brass moves backwards if there is a gap, expands and gets stuck, then stretches backwards.

There may well be a gap at the moment of firing.

Extractors aren't perfect.

The cartridge will be pushed forwards by the impact of the firing pin on the primer. And before that by gravity if the muzzle is a little downwards.

After firing, the firing pin spring retards the rearwards motion of the brass because it is in contact with the firing pin. For a fraction of a second.

So I'm asking if the couple-thousands gap in the lugs goes away (due to forwards movement of the barrel) before or after the couple-thousands gap between brass & breechface goes away (due to rearwards movement of the brass).

If both barrel and slide are in motion (in opposite directions) then the force of the impact on the upper lugs is the sum of both, NOT just the force of the slide movement -- which is the only aspect that I have ever heard mentioned. So do all the existing calculations really significantly underestimate the force?

Re donut-- its only a thousandth or two thick, and could be tapered from the bottom. Sure, it can only correct one "direction" of excess headspace. It might be tapered from .004 at the top to 0 at the bottom, and momentarily squash down to .002 under firing pressure. But not instantly, so it might effectively improve the gap by .003 for as long as it takes for the bullet to engage the rifling.

Re barrel foot impact -- there are some very strong polymeric materials. That is why they are replacing metal in many applications. The fact that a polymer will _flex_ is an asset. The closing slide pushes the barrel feet down into the polymer, which flexes to absorb the momentum and then recovers its shape, thus pushing the barrel upwards into full engagement with the slide. A couple thousands.

[1911Tuner]

InTheBlack...Once again, I'd suggest that you go study the way the 1911 really functions. You ain't quite got it yet...but I have hopes. ;)

[gottripletsNC]

Brass moves backwards if there is a gap, expands and gets stuck, then stretches backwards..

Huh? I'm not sure what you are saying.


There may well be a gap at the moment of firing.

Not enough to matter


After firing, the firing pin spring retards the rearwards motion of the brass because it is in contact with the firing pin. For a fraction of a second..
Negative, the firing pin spring fights the firing pins ability to move forward, helps hold the pin back to prevent accidental discharge and to pull the pin back once the round is fired before the next round loads, thus preventing damage to the pin. the spring has no possible way to come in contact with the casing, and surely by design is not going to hold the FP out.



If both barrel and slide are in motion (in opposite directions) then the force of the impact on the upper lugs is the sum of both, NOT just the force of the slide movement -- which is the only aspect that I have ever heard mentioned. So do all the existing calculations really significantly underestimate the force? ..

It took me some time to understand this one, because its an unusual concept from what you would deduce, but once I realized it, it made sense. Your assumption is wrong, Initially they are moving in the same direction...forward (right tuner - fingers crossed). after a very brief moment the upper lugs seperate and then the slide is pushed backwards by the recoil of the round. My understanding is that by this design, all energy is expended into the slide which is dissipated in the recoil spring.


Re donut-- its only a thousandth or two thick, and could be tapered from the bottom. Sure, it can only correct one "direction" of excess headspace. It might be tapered from .004 at the top to 0 at the bottom, and momentarily squash down to .002 under firing pressure. But not instantly, so it might effectively improve the gap by .003 for as long as it takes for the bullet to engage the rifling.

Re barrel foot impact -- there are some very strong polymeric materials. That is why they are replacing metal in many applications. The fact that a polymer will _flex_ is an asset. The closing slide pushes the barrel feet down into the polymer, which flexes to absorb the momentum and then recovers its shape, thus pushing the barrel upwards into full engagement with the slide. A couple thousands.

an opening slide would cause the feet to drop down, in a closing slide the barrel feet move up into position on the slide stop pin, not the frame bottom

the 1911 is a simple design by other standards, but a very finessed design that many still don't fully realize the genius of JMB, and I will say that I have learned an immense amount on the function of the gun from Tuner, John, Wichaka, and quite abit from Stans too, btw John I haven't seen Stans in quite a while now that I think about it.

Study up a lil more there intheblack....I continue to study the design.

[1911Tuner]

Puttin' on the popcorn and pullin' up a chair. This is gonna get interestin' real soon... :D

Okay...Okay! I'll go ahead and start with the most basic errors.

The brass doesn't expand...get "stuck"...and stretch with a straight-walled pistol case like it does with a bottle-necked rifle case. The case backs out of the chamber until it encounters the breechblock, thus taking up the
"gap"...which is the difference between static headspace (fixed) and working headspace.(variable) This gap is also known as positive headspace, compared to zero headspace...no gap...and in direct opposition to negative headspace, in which the cartridge case length exceeds the static headspace.
Static headspace being the linear distance from breechface to cartridge stop shoulder with the gun in battery.

The gap between the breechface and backside of the extractor hook is necessary. This gap should be a minimum of .0625 inch, and I like to see
about .075 or a bit more. Otherwise, I have to make an extra cut on the bottom of the extractor hook to insure smooth, reliable function as the rim slides under the hook at that angle. (And that angle is also necessary for the
gun to function as a controlled feed design.)

I won't even expound on the polymer thing. That's too far-fetched even for Gaston Glock... :p

[InTheBlack]

If JMB were alive today, he would be using polymers!
***

Oops-- when I said firing pin spring, I meant mainspring:
Mainspring pushes hammer pushes firing pin pushes primer...

This coupling between the primer and mainspring could momentarily retard the backwards movement of the brass.

EDIT: I'm assuming the firing pin is long enough so that when the rear is flush with the firing pin stop, the forward end of the pin protrudes from the breechface. Maybe I'm just wrong about that.
Otherwise:

Is the impulse from the primer strike, minus deformation, enough to push the brass away from contact with the breechface faster than the recoil spring can pull the slide forwards to maintain (or regain) that contact before powder ignition starts pushing the brass backwards?

***

At rest, the recoil spring pulls the slide forwards into contact with the barrel lug. Is the impulse, from the bullet pushing the barrel forwards, sufficient to create a gap between the lug and the slide, faster than the recoil spring can pull the slide forwards to maintain (or regain) that contact, before powder ignition pressure moves the slide backwards into barrel lug?

If the at-rest gap between the _front_ face of the barrel lug and _back_ face of the slide is "small enough" then the forward movement of the barrel might be stopped by hitting the slide, and maybe bounce back into proper contact with the slide, _before_ the slide starts moving --so that when the slide begins moving backwards it does not "slap" the barrel lugs.

***

I know that at Bullseye pressures, you don't see elongation or web stretching of .45 ACP brass. But what about at full duty load pressure? I'm thinking of the importance of breech face pressure being reduced by "sticktion" holding the brass against the chamber walls. Which is why you don't want oil in the chamber.

***

>>>
an opening slide would cause the feet to drop down, in a closing slide the barrel feet move up into position on the slide stop pin, not the frame bottom
>>>

I though that Tuner said that in some old, well fitted barrels, the bottom of the feet rested upon the frame "at rest" instead of being lifted up by the stop pin.

So the height of the feet cause the upper barrel lugs to go up into full vertical engagement with the slide. Maybe I misunderstood- too many pages of brain buster information.

[1911Tuner]

Quotes:

>I know that at Bullseye pressures, you don't see elongation or web stretching of .45 ACP brass. But what about at full duty load pressure? I'm thinking of the importance of breech face pressure being reduced by "sticktion" holding the brass against the chamber walls. Which is why you don't want oil in the chamber.<

You don't see stretching at standard pressures either. For one...there's not enough of a difference between Bullseye "softball" ammo pressures those generated by and GI hardball. A centerfire rifle caliber would vary as much...or more...from round to round as the difference would amount to.

You don't have the venturi created by the shoulder and neck with straight-walled cases, nor the pressures involved...both of which tend to keep bottlenecked rifle cases nailed to the chamber walls. In these...excessive headspace stretches brass ahead of the web and forms the line around the ircumference known as "Incipient Case Head Separation."

Straight-walled cases follow the path of lease resistance, and simply back out of the chamber until they're stopped by the breechface. Signs of excessive headspace show up as half-moon shaped bulges just ahead of the web. These bulges correspond with the barrel "throat" which is the area of reduced head support.

***


>>an opening slide would cause the feet to drop down, in a closing slide the barrel feet move up into position on the slide stop pin, not the frame bottom<<


Correct.

>>>I though that Tuner said that in some old, well fitted barrels, the bottom of the feet rested upon the frame "at rest" instead of being lifted up by the stop pin.<<<

Either on the feet or by the link in compression.
****************

So the height of the feet cause the upper barrel lugs to go up into full vertical engagement with the slide. Maybe I misunderstood- too many pages of brain buster information.

Correct. In a gun that is correctly fitted or within spec, the barrel is cammed into vertical engagement by the slidestop pin and lower barrel lug feet.
Though there are some that pivot on the link into vertical engagement...it's
not correct, and stresses the link, the lug, and the link's mounting pin.

As for JMB...If he were alive today, he'd either be ROFL or cryin' like a baby over what we've done to his pistol. :D

Maybe I misunderstood you, ITB...You seem to have a pretty good grasp on it. ;)

[Dr. Dickie]

Howdy Doc,

The disconnect moves on two axes...Up/Down and In/Out. Study the square hole in it.

The fact that the slide uncovers the disconnect when fully rearward is incidental. Even if the disconnect could reset, when the slide moves forward again, it cams back down into the disconnected position.

Right I got ya! I played with that after reading your description before, and you (as normal) were dead on! ;)
That was one of the pleasures of replacing the trigger on my Commnader, seeing how things moved and were set in there after reading so much about it in your descriptions.
But in the real pistol, does the slide travel so far back that the disconnect is uncovered?
No need to answer, I am going to the range today, and I will look for myself (curiousity does not allow me to have anything that I do not at least understand well enough to get into trouble).
BUt don't stop the discussion, I may be slow but I AM learning :D

[1911Tuner]

Ya don't gotta go to the range, Doc. Lock the slide back and take a peek.
You'll see the little nubbin wavin' atcha.

[Dr. Dickie]

Ya don't gotta go to the range, Doc. Lock the slide back and take a peek.
You'll see the little nubbin wavin' atcha.

Yep, as always, right on Tuner. I pulled the slide back that there it was. I always thought it didn't get uncovered on the recoil (even though it would not re-set until the trigger was released--I learn another one).
Oh and the firing pin stop, like butter. The pistol performed wonderfully with just a light bevel on the FP stop. I shot better than I have before.
I wish I could say that I really noticed the reduction in recoil, but while I shot great, the day at the range was miserable. I had constant 3 point jams (about every third round). I blame the ammo. It was handloaded SWC with an OAL of 1.255" and they were not clearing the magazine mouth (just missing by about 0.005"). At first I thought it might be the new tightness of the extractor, but the back of the round was not making it to the extractor--the rim was still, just barely held by the flair of the mag.
Since the week before I had made up 50 rounds at this OAL, I made up 200 to shoot on Friday :butthead: . Well, I got through them, but I don't want to have to clear my weapon that many times again ;)
Think I will make up 50 at 1.250" and 50 at 1.455" for this Friday.
(I'm going to give that STI video another look see).

[1911Tuner]

Doc,

If you're using the 200-grain H&G SWC bullets, seat'em at 1.240 inch.
Likely the bullet shoulder is hitting the chamber shoulder and tyin' up the gun.
If your headspace is close to minimum, you may need to seat at 1.235 but 1.240 will probably do.

[jbj16]

Hi Guys! My first post here. IMHO what Tuner says is grossly wrong with the STI animation is this. The barrel's 3rd and 2nd upper lugs would get a bad peening had it been functioning like that for even 50 rounds. Shown as is, the slide's lug recess batters the barrel lugs prior to initial barrel aft movement. :nono:

[1911Tuner]

Hi Guys! My first post here. IMHO what Tuner says is grossly wrong with the STI animation is this. The barrel's 3rd and 2nd upper lugs would get a bad peening had it been functioning like that for even 50 rounds. Shown as is, the slide's lug recess batters the barrel lugs prior to initial barrel aft movement. :nono:

Howdy jb, and welcome in.

Nope...that ain't it. The problem is that the animation shows the bullet exiting before the slide moves. That can't happen. If the bullet is gone before the slide moves, the slide won't move.

I'll go look at what you're referencing...but the barrel doesn't move rearward until the slide does. The barrel lugs' front faces engage the slide's rear lug faces as the slide is driven rearward and the barrel held hard forward by the pressure and bullet friction. This is the point that the breech locks.

I'll go see what you're describing and report back.

Back! The lug interaction in the animation is correct and accurate, jb.

[Dr. Dickie]

Doc,

If you're using the 200-grain H&G SWC bullets, seat'em at 1.240 inch.
Likely the bullet shoulder is hitting the chamber shoulder and tyin' up the gun.
If your headspace is close to minimum, you may need to seat at 1.235 but 1.240 will probably do.

Thank you sir.
I am using the Hornady 200 gr SWC (with FMJ), but I 'pect the profile is close enough that I should be using 1.240" (just trying to tweak a little closer to the rifing for accuracy--won't make that mistake again ;) )

P.S. Okay, I looked at the STI again. The only minor thing that gets me is that the ejected shell goes out holding the horizonal angle throughout the ejection process. But in reality, held by the extractor on the right side and slammed into the ejector on the left side, it should "flip" out of the ejector port.

[1911Tuner]

I'm findin' all kinda things wrong with the ATI animation!

It shows the barrel as parallel with the slide axis in lockup...Wrong!
The barrel tilts up at the rear in battery...butt-end high/muzzle low.

Maybe I need to shoot an E-mail to STI... :p

[1911Tuner]

Found another one! Minor point...but still wrong.

The animation shows the hammer cocking smoothly and the hooks in contact with the sear through the entire cocking phase. The reality is that the hammer is slammed back...overcocks...strikes the grip safety, and rebounds back against the slide. When the slide goes to battery, the hammer drops into hook/sear engagement.

Think STI would put me on the payroll as a technical consultant? :cool:

I'll go back and double-check...just to make sure I didn't miss somethin'.

Back!

Okay...It shows the over-cock, but not the hammer whackin' the grip safety. I'll let'em pass on that...but not the recoil/slide movement sequence. Utterly wrong!

[John]

OK, I emailed the creator of the animation with the two mistakes (bullet leaving the muzzle and the the slide starts its rearward travel and the barrel being parallel to the slide axis).

Let's see if he is interested to correct them. I'll let you guys know.

[1911Tuner]

OK, I emailed the creator of the animation with the two mistakes (bullet leaving the muzzle and the the slide starts its rearward travel and the barrel being parallel to the slide axis).

Let's see if he is interested to correct them. I'll let you guys know.

I wouldn't hold my breath, bossman. Some experts get in a snit when you tell'em they made a mistake... :D

[OD*]

It shows the over-cock, but not the hammer whackin' the grip safety.
I just checked mine Johnny, none of these do.
They will, if you thumb cock them though.

[1911Tuner]

I just checked mine Johnny, none of these do.

It does when you shoot it...You just can't manually cycle it fast or forcefully enough to make it slap the top of the grip safety.

And the hammer overcocks, then falls back onto the sear when the slide gets off of it. That part you can see by hand-cycling.

[OD*]

I suppose that could be, I would think it would at least "mark" the tang.

[1911Tuner]

I suppose that could be, I would think it would at least "mark" the tang.

It does. Ever noticed the shiny line on pistols with spur hammers and standard grip safeties? Another clue is to look on the underside of the slide, on or just forward of the firing pin stop. You should see light peening from the hammer hitting after rebounding off the grip safety. Incidentally, that's a quick way to determine if a seller is telling the truth about a gun being fired
"Only a box or two" or much more...Old, softer slides will show it earlier than modern hardened slides.

[OD*]

I just had to check all of them. :D

No peening on any on them (two of them are older, 1913 & 1940, hard slides began in 1947, IIRC), just nice smooth wear. About half have a slight mark on the grip safety, one has a mark and has never been fired (by me, bought new) and it had no marks when I brought her home.

Interesting subject.

[1911Tuner]

I just had to check all of them. :D

No peening on any on them (two of them are older, 1913 & 1940, hard slides began in 1947, IIRC), just nice smooth wear. About half have a slight mark on the grip safety, one has a mark and has never been fired (by me, bought new) and it had no marks when I brought her home.

Interesting subject.

That means that either:

A...They haven't been fired more than a couple thousand rounds.
B...The ammo has been consistent and has worn the corner at the FP stop
into a radius.
C...The mainspring has been changed regularly about every 5,000 rounds.
D...The mainspring is badly worn and the hammer is hitting further forward on the center rail.
E...The older pistols have been refitted/rails peened/slide lowered and the disconnector rail stoned smooth.
F...Any combination of the above.

I'll post a few pictures later on.

[1911Tuner]

#1. 1943 Colt slide.
#2. Much-used Norinco slide.
#3. Hammer mark on grip safety.


http://i40.photobucket.com/albums/e243/1911Tuner/Peen2.jpg

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

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

[1911Tuner]

The lighting made the marks look much worse than they are...and made the firing pin stop radius on the Colt look cattywampus...but it's okay. Trust me. :)

Anyway...just to clear things up a bit. The live cycle of a 1911 pistol isn't smooth. It's a fairly rough, slam-bang operation.

[OD*]

A...They haven't been fired more than a couple thousand rounds.
That would apply to several, about half.

B...The ammo has been consistent and has worn the corner at the FP stop
into a radius.
Radius on the firing pin stops appear the same, with the exception of the 1913 an it's original .078R.

C...The mainspring has been changed regularly about every 5,000 rounds.
Not by me :D

D...The mainspring is badly worn and the hammer is hitting further forward on the center rail.
No indecation of that.


E...The older pistols have been refitted/rails peened/slide lowered and the disconnector rail stoned smooth.
Nope.

F...Any combination of the above.
Could be. ;)

[1911Tuner]

OD Quote:

>Radius on the firing pin stops appear the same, with the exception of the 1913 an it's original .078R<
**********************

Sorry. Wasn't clear. Not the radius of the stop. The corner of the slide butts up against the inside of the stop. That corner will radius.

Shoot the guns enough, and you'll start to see it. Modern, hard slides may not show much deformation for up to 5,000 rounds...and when it becomes noticeable, it will usually be a slight radius at that corner. The first sign is finish wear in the area and a polished appearance. In some guns with weak or underpowered mainsprings, the hammer will strike further forward on the disconnector rail, making it harder to spot...but it's there. I've seen Series 80 Colt slides nearly flatten the thin section adjacent to the firing pin plunger hole.

Older, pre-A1 pistols with the shorter grip safety tangs generally
hit further forward because the hammer travels further in overcock...and since it takes a little longer to rebound from there, the strike is slightly forward of the corner...about a 10th inch.

[Dr. Dickie]

I'm findin' all kinda things wrong with the ATI animation!

It shows the barrel as parallel with the slide axis in lockup...Wrong!
The barrel tilts up at the rear in battery...butt-end high/muzzle low.

Maybe I need to shoot an E-mail to STI... :p

Wow! That is fascinating to me. Why have the barrel tilt down!
I mean, I understand that this is a pistol and you would not be expected to shoot long distances, but parallel or even slightly up I could understand, but slightly down?
(maybe I have another excuse for shooting low :p )

[OD*]

Sorry. Wasn't clear. Not the radius of the stop.
Yes you were Johnny, I misread your post originally, my fault.

The three I know for certain that have way more than 5,000 rounds through them show no signs of deformation, now they do have the polished appearance.

[1911Tuner]

Yes you were Johnny, I misread your post originally, my fault.

The three I know for certain that have way more than 5,000 rounds through them show no signs of deformation, now they do have the polished appearance.

It may not go much futher thant that. My 91A1 beaters radiused the corners
fairly early one...at about the 10-12k mark and have remained pretty much the same. One has a little more peening...another a little less. Variables dictate the amount.

On the ones that really get pounded, it normally doesn't amount to much more than what was shown on the two in the pictures. In other words...Only rarely will it cause a fuctional problem, and usually only in difficulty removing the firing pin stop if the metal gets flanged. Colt Series 80s that take the hit around the plunger can present a problem though. Keep an eye on those.

[OD*]

Colt Series 80s that take the hit around the plunger can present a problem though. Keep an eye on those.
Good advice sir, thank you.

[Involute]

I'm goin' all the way back to the beginning on this one Tuner...

What kind of pressures are you using when you proof equalize the lugs? +P, +P+, 45 Super? Any of those close?

What are your preferred barrels for doing the perfect fit job?

[1911Tuner]

I'm goin' all the way back to the beginning on this one Tuner...

What kind of pressures are you using when you proof equalize the lugs? +P, +P+, 45 Super? Any of those close?

What are your preferred barrels for doing the perfect fit job?

Howdy Involute.

First...Understand that in order to fit for lug equalization, you have to have a
reliable means to measure the distance form breechface to the rear lug face of all three lugs. Otherwise, just buy a Kart Easy-Fit and follow the instructions. Unless the lug locations in your slide are badly out of spec, the KEF system will fit to the #1 lug 95% of the time, and about half the time, you'll pick up one of the others...either right away or within 500-1,000 rounds.

For the money, it's hard to beat Kart's barrels...Easy-Fit or full fit. Excellent barrels. I haven't been disappointed yet.

For pressure equalization, there are a few caveats.

Many years ago, it was pretty much SOP to get #1 bearing the load, nad leave lugs 2 and 3 to within .002-.003 inch of contacting...and equalizing with proof-level ammo. The softer steels allowed that approach with good results. These days, the steels are harder, and require more time to settle back and equalize, and I do NOT recommend it with proof-level ammo unless you've actually fit for equalization, and/or the lugs need less than .002 inch to come into play. Much better to do it more gradually with lower pressures
than to bust a lug.

You can speed it along with a handload that I've used in the past, but start
a full grain below this data and work up to it in 2/10ths increments.
The seating load is: A 250-grain jacketed bullet and 6.5 grains of Unique.
You may want to use a hard cast lead bullet for the first 4 or 5 rounds, followed by the jacketed bullet for another 4 or 5. Then just shoot the gun
with hardball-spec 230...about 500 rounds should be enough, unless your lugs have farther to set back than .002 inch. After firing the heavy rounds, check the barrel lugs for flanging at the top front, and stone it flush with the top surface of the lug. If you see flanging, the lugs are being deformed a little, and that means that they're being set back toward equalization, and if your initial fitting was done correctly, that may be all you need. The lug that's bearing the brunt will have the heavier flange...or if there's only one lug in the game, it'll likely be the only one that gets flanged. If that amount of setback brings one of the others in, that may be all that you see. A note: Heavy bullets seat the lugs faster than light ones...even if the light ones are loaded to +p+ pressures.

Also, due to the fact that the barrel tilts INTO battery, lugs 2 and 3 may not show evidence of full-depth seating, even though #1 is. Typically, 2 will have a few thousandths less, and #3 a few less than #2.

Lastly, whatever amount of lug setback occurs, the working headspace will increase by that amount, as will barrel to slide endshake, so fit the hood to breechface with light to medium contact to allow for the seating process.
After seating and break-in, if that contact is still a little too tight for your tastes, you can take another couple thousandths off the face of the hood to get some "dirt clearance" there. I like about .003 inch for the best compromise between accuracy and reliability.

[Lazarus]

Let me just say thanks for the excellent barrel fitting info. Knowing what to shoot for gives me a whole lot more confidence when judging a barrel's fit.

To round out the discussion (I don't think I missed it...) I'd like to request a few comments on the procedure for dealing with where the firing pin strikes the primer. It is clear that every slide is going to have different dimensions and that upper lug engagement is first on the list of priorities. Kuhnhausen shows a tool that locates the firing pin port dead center with the chamber, but most of us won't be boring our firing pin ports after fitting a barrel! At what point in the barrel fitting process do we assess the position of the f.p. relative to the barrel height and make adjustments if necessary? :confused:

A related question: I noticed that one of my 1911's shows noticeably more black burned powder marks on the outside of the spent brass than the others. The marks are concentrated on one side of the spent brass. Do the powder marks (along the length of the case) by themselves indicate that the the barrel may be linking down too early before the pressure drops? Or perhaps the marks vary depending upon the actual chamber diameter and type of brass used?

I've studied some of the Schuemann barrels that actually have fluted chambers. They are supposed to cause the cartridge to "self-center" in the chamber by letting some of the high pressure gas flow around the brass. I always wondered about that design, and whether your chamber would get clogged up really quickly.

Thanks!
Lazarus