1911 Clinic. The barrel link


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bigjim
December 27, 2003, 07:39 PM
What is the barrel link? What does it really Do? How do you know your barrel link is the right size?

What is the correct name for the ramped projection that the barrel link rides in with the pin through it to hold it in place? What is the purpose of this "barrel foot" besides holding the link to the barrel?


See attchment for a picturehttp://www.thehighroad.org/attachment.php?s=&postid=687413

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BigG
December 27, 2003, 08:04 PM
That's the bbl lug. The profile of the lug follows the slide stop pin to unlock and lock the bbl. According to 1911Tuner, the link just keeps everything in place and does not do much for bbl lockup or unlocking. The lug needs to be accurately machined for the pistol to work right. I know Jerry Kuhnhausen's book stresses cutting the lug accurately. HTH

1911Tuner
December 27, 2003, 08:05 PM
Ah! The oft-misunderstood link. Due to some misconceptions
about that simple little machine, I'll watch this one for a while
to get some input.

One thing that I will say is that the link is NOT supposed to
put the barrel into vertical lock, though many ill-informed
tinkerers install a longer link in hopes of enhancing accuracy
with a better vertical lockup. While a long link will often remove
vertical barrel play, it won't help the accuracy,and as often as not,
will actually make it worse. In fact, when the barrel is in vertical lock and the slide in battery, the link should be under no load at all. If the link
bears the load of vertical lockup, the condition can do damage if allowed
to remain for very long. Depending on how MUCH of a load that it bears,
and how long it delays barrel linkdown, the damage can be done in as little as 100 rounds.

Now that there's a mad scramble to remove all those long links, I can
sleep better tonight.:D

Nitey-nite!

Tuner

Delmar
December 27, 2003, 08:18 PM
How do you check the lock up to make sure the lugs are bearing on the cross pin when in battery?

1911Tuner
December 27, 2003, 08:26 PM
Delmar asked:

How do you check the lock up to make sure the lugs are bearing on the cross pin when in battery?

Color the lug with a blue, chisel-point felt tip marker...Marks-a-lot is a good one. Look for even rub marks just at the point that the pin starts to go around the corner all the way to lockup. Note that if there is vertical play in the barrel, you'll get a false reading. If the rub marks start after the pin has engaged the bottom of the lug, the barrel is riding the link a little.


Tuner

Jim K
December 27, 2003, 08:43 PM
The link plays (or should play) no real role in barrel lockup. This can be tried simply enough by removing the link and working the gun without ammo. The cam surface of the "foot" rides up on the slide stop to lock the barrel. If the barrel "rides" the link during lockup, the narrow center contact allows the barrel to be "wobbly" and accuracy suffers. That is why folks recommend that the barrel "feet" be even and bear evenly on the slide stop, rather than the link bearing on the slide stop.

But the link IS needed for positive unlocking. Again, easy to try at the same time. Remember, in recoil, the barrel-slide unit will remain locked until an outside force (outside the barrel-slide unit, that is) unlocks them; that force is the link, which is fixed at one end and allows a circular motion at the other, drawing the barrel out of engagement with the slide.

Barrel movement begins at the same time the bullet begins to move, but the greater weight of the barrel-slide unit keeps the unit locked until the bullet exits the barrel. Yes, this means that the barrel is actually moving while the bullet is still in it, another reason to ensure the barrel-slide stop contact is correct. Kuhnhausen, very good in other ways, says some "thrust vector" keeps the barrel from moving until the bullet exits; he is wrong, and his "thrust vector" is nonsense.

Jim

1911Tuner
December 27, 2003, 10:05 PM
Welcome Jim Keenan into the fray. Jim is a savvy old pistolsmith up in
Maryland, U.S.A. He knows his stuff, but he ain't in the habit of chewin' his
cabbage twice when somebody wants to fight over a fact. He's also a helluva nice guy that will take the time to explain something,and has experience with many gun designs and models aside from the 1911.

This is gonna prove to be a good workshop. Let the discussions and
debates begin!

Tuner

bigjim
December 27, 2003, 10:30 PM
OK fellas,

I hear what your saying about the link pretty much just acting as a lever to pull the barrel out of battery but.....


How does this jive with the existence of the Wilson group gripper guide rod that uses a spring loaded link to force the barrel up?

Inquiring minds want to know!

bigjim
December 27, 2003, 10:38 PM
Thanks Jim,

That helped me a good bit. So is it safe to say if anyone ever recomends long linking a 1911 to make it more Accurate they are full of crap?

Delmar
December 27, 2003, 11:30 PM
I must be missing something here-if the barrel begins to move backwards at the same time the bullet is headed towards the muzzle, then why is lockup at the barrel lug so important? Is the barrel NOT floating somewhere between full lock and rearward movement?

Just swagging here, but I would think the bullet, being of much less weight would begin moving first because of its lighter weight? BTW, I don't buy into Kuhnhausen's theory of the bullet out of the barrel before unlocking begins-the pressure would be gone when the bullet exits the muzzle, and in order to have inertia, you have to have movement and weight.

romulus
December 28, 2003, 12:11 AM
What is the barrel link? What does it really Do? How do you know your barrel link is the right size?

What is the correct name for the ramped projection that the barrel link rides in with the pin through it to hold it in place? What is the purpose of this "barrel foot" besides holding the link to the barrel?

I think that projection is called the "barrel bed" or the "frame bed". The barrel foot is supposed to mate with the slide stop pin for maximimum lock-up (no discernable play). As to right size, I hope to find out by sticking with your lesson plan.

Thanks

BigG
December 28, 2003, 12:17 AM
Delmar, I think I know what you are asking, so here goes. What you are thinking about is the timing of the unlocking.

If you look at the picture of the lug, you'll notice two small projections at the rear. Those are known as the barrel feet. The slide lock pin is up against those feet when the gun is in battery. It is also riding on the flat portion of the lug. You'll notice that the curve of the lug is not a nice circular profile but flat before it starts to curve. This is a guess, but I think the barrel moves STRAIGHT back about maybe 1/16" before it starts to go down to unlock. That's the dwell time that the bullet has to leave the bbl. The old master balanced the two forces, i.e., the bullet and the slide masses and figured that that distance was enough to allow the bullet to leave the bbl and release the pressure. They are both moving at the same time, but the heavier mass moves so much slower. What you are maybe not taking into account is that the process of firing the cartridge has hit the slide with the same force as the bullet. The lesser mass moves first, but the slide has also received a helluva kick. So the inertia of that kick completes the action of cocking and the spring returns the slide to battery.

What I'm saying is, the bbl is fully locked during that 1/16" or so that it travels to the rear before the slide stop pin hits the curve of the lug. So it is fully supported (not floating) while the bullet is in the bbl and would have no effect on accuracy if properly fitted. HTH

Delmar
December 28, 2003, 12:25 AM
Thanks, Big G. I had an idea this might be the case, but it always helps to hear it explained, too. I've been fooling around with the 1911 for over 30 years, and understand alot, but always willing to listen and learn. This forum would never be the great place it is without the people we are blessed to have here.

bigjim
December 28, 2003, 12:39 AM
Thanks guys this is exactly the kind of tone and exchange of information I was hoping for.

I hope some Anti-gunners are watching.

Jim K
December 28, 2003, 01:03 AM
Delmar is correct, though it is a bit more than 1/16". The distance is critical and can affect extraction and other areas.

There are plenty of high speed movies showing (when projected in slow motion) the barrel moving backward before bullet exit. The force involved is recoil, which is why the gun is called (surprise!) a recoil operated pistol. Some folks just can't accept recoil since it is something that sort of has to be taken on faith, so they come up with the drag of the bullet in the barrel, or the pressure on the slide, and other ideas. A blowback action is more easily understood because we can grasp the idea of pressure moving the slide. But the 1911 and all similar pistols (even ones as unlike as the Luger and Mauser C96) work on recoil from the forward motion of the bullet.

Simply put, if the bullet does not move, the gun will not operate; the pressure itself will NOT move the barrel or the slide and the gun will not unlock.

This was once called Newton's third law of motion (for every action there is an equal and opposite reaction) but now has been Borax freshened and lemon scented and put out as the Law of Conservation of Momentum. Still basically the same thing. Mass x velocity in one direction equals mass x velocity in the opposite direction. The bullet is small mass times high velocity, the barrel-slide unit is large mass times slow velocity, so they equal out.

HTH

Jim

Old Fuff
December 28, 2003, 02:10 AM
Actually the use of “long links” to lock the barrel into battery was first popularized by the folks at Springfield Arsenal during the late 1950’s. They were trying to develop a match grade .45 for armed forces’ match teams and civilians who competed in the National Trophy Pistol Match held at Camp Perry, Ohio each year. During these early days they had to use modified service pistol parts, and to achieve a tighter lock-up they had set of barrel links with longer then normal spacing between the holes. When an armorer built a gun he would experiment to find the particular link that gave the best, but not a perfect lock up. So long as the barrel wasn’t forced or “jammed” into position this system worked.

By the early 60’s they had developed a true “match grade barrel” that had extra metal on the hood and link-lug that allowed individual fitting on each pistol. With this system the lower hole in the link was drilled oversized and only served to pull the barrel down while the slide moved backwards. The barrel was cammed upward by the lug pushing against the slide stop pin. This was much better then the previously used “long link” which was quickly abandoned. This resulted in excellent bull’s-eye match pistols, but had one serious drawback in a service gun. If excessive fouling or dirt built up in the slide in the area of the barrel locking lugs the piece might refuse to go into battery.

In my view the “long link” system still has a place on a carry gun (read that as “personal weapon”) IF IT IS CORRECTLY FITTED. If it isn’t you will get all of the problems Tuner alluded to. From the point of view of maximum accuracy a tightly fitted, lug-cammed barrel is unquestionably the way to go. However this accuracy may come at the price of reduced reliability – particularly in a dirty environment.

One may also opt for a lug-cammed barrel that is slightly less then fully locked, which offers a compromise of a little less accuracy in exchange for some additional reliability.

Jammer Six
December 28, 2003, 03:50 AM
Kuhnhausen, very good in other ways, says some "thrust vector" keeps the barrel from moving until the bullet exits; he is wrong, and his "thrust vector" is nonsense.


Jim, that's twice you've said that.

Where does Kuhnhausen say this?

I have both volumes, and would like to read what he says about "thrust vectors".

Thank you.

1911Tuner
December 28, 2003, 04:50 AM
Excellent! So far, so good. Many questions have been asked and answered. Kudos to BigG for his explanation to Delmar.

The barrel and slide move straight back for a distance of about 1/10th
inch and the barrel STARTS to unlock at that point, as the slidestop
pin reaches the upper part of the forward curve of the barrel lug. By the time the slide has traveled a quarter inch...the barrel should be completely unlocked from the slide and in the bed, or as some call it, the saddle. When the barrel is in the bed, there should be a small gap between the top of the barrel and the underside of the slide. This gap should be a .012-.015 inch. I like to see .018-.020 inch, but that's just me. These figures assume that the lower lug is in-spec, and the link is the proper length.

The link TIMES the event. If it's too long, the barrel is held to the slide
for too long. The lugs can be impacted by the lugs in the slide, and they
become "rolled" on the front. This damage can extend to actually starting
a shearing action on the lugs...and the lugs in the slide begin to show damage as well. A link that is too long can also bring this damage about
when the rear of the barrel lug hits the impact surface in the frame while the link is in a bind with the slidestop pin. The barrel is captive for a brief
time, and the lugs get hit.

On the other hand, if the link is too short, the barrel begins to unlock
too early, while chamber pressures are still high. This can undermine
the case head support and put additional stress on the extractor hook
as it tries to yank the still expanded case out of the chamber.

With the link in the In-Battery position, the radius in the hole should align
with the radius in the lower lug at the rear and the bottom. If the link's
hole protrudes above the lug, the link is too long, and is bearing the load
of vertical lockup, and all sorts of bad things can occur.

The pin hits the lug feet toward the tips instead of in the radius. The tips of
the feet get damaged by the slide going to battery. The pin that holds the
link in the lug begins to wallow out the hole that it's pressed into, and the
interference fit is lost. The bent feet and sloppy action in the link delays
linkdown timing. Incidentally, this is why letting a slide slam into battery on an empty chamber is a bad thing to do to an autopistol.

Now, go to the front curve of the lug. When the barrel is in linkdown, the
link doesn't lay flat against the barrel. It swings to a point that roughly
aligns the radius of the hole in the link to the center of the convex radius
of the lug...or just slightly past center. As the slidestop pin goes around the "corner", the pin should make light contact all the way, if the lug is correctly dimensioned. If it's not, and the pin is held away from the lug,
the barrel is riding the link...even though its length is correct in lockup.

Most production pistols' barrels ride the link to some degree, and it won't
hurt anything for many thousands of rounds, and then it's usually just a
slight loosening of the pin. Since these pins come in oversizes in .001
increments, we can fix the problem with the next size up.

In this situation, we can go to a slightly shorter link, provided that the
link isn't being stretched as the barrel links down, and it doesn't get the
pin in a bind as it goes back around the corner toward vertical lockup.
The hole in the link can be slightly BELOW flush with the lug...just not above flush. .003 inch shorter seems to be about the limit in any case,
due to the stretching forces against the link as the barrel comes to full
linkdown. In some instances, we can't go to a shorter link due to the dimensional tolerances of the impact surface in the frame to the backside
of the lower lug. Most of the time, we can.

Going to a slightly shorter link has one distinct advantage. It can reduce
a slight stem bind condition during the feeding stroke. Whenever you run
into a failure to return to battery, and you notice a crescent-shaped mark
on the case just below the mouth, you have stem bind. By going to a
slightly shorter link, you delay the barrel rise for a few degrees in the
arc. When the round is stripped from the magazine, it hits the barrel
throat at some point, and this causes the barrel to move forward. When
the barrel moves forward, it also begins to move UPWARD, due to the
link's influence on the barrel, when the barrel rides the link. The longer the
link, the faster it swings upward, and the higher it will be in relation to the
barrel's forward movement. It's a mechanical ratio. Think of a pole vaulter
when he sticks the pole in the vaulting cup as he races toward the bar. The higher up on the pole his hands are positioned, the faster he will rise,
and the higher he will vault. He is the barrel riding the link.

If your barrel is riding the link, and you want to make the pistol feed
more smoothly...try going to a slightly shorter link. There is a limit to
how MUCH shorter you can go. To find it, remove the bluing from an old
slidestop pin, and color it with machinist's layout fluid, or a felt-tip marker.
Install it through the link with the slide and barrel on the frame, and
leave the arm hanging vertically. Leave the recoil spring and plug out of the slide, and push the slide fully rearward. Push the barrel down and
back into the frame and hold it there with moderate pressure. The slidestop should swing freely without binding. A very tiny bit of bind is
okay, but ideally, it should swing free of its own weight. If it binds, remove
it and see where the bluing is removed. If bare metal is showing at the
front, the link is too long. If it's at the rear, it's too short.

Blueprint specs call for a center to center length of .278 on the link. I've
found that a .275 link can be used in most production pistols. This is
the essence of fine-tuning, and helps us to understand why some pistols will feed almost anything, while others are finicky about the overall cartridge lengths. The link plays a part.

Cheers!

Tuner

bigjim
December 28, 2003, 01:17 PM
Thanks guys,

Tuner, Jim, Old Fuff, BG,

I have several guns part now and I am looking at what you have all mentioned and am trying to understand it. Thanks a lot!


I have printed Tuners last post and I Am using it as a bench mark reference since it is quite clear. Does anyone else disagree strongly with any of his assertions?

I am planning to keep what we come up with in each of the clinics and post them back here as a compilation.

1911Tuner
December 28, 2003, 01:32 PM
Mighty welcome bigjim.

Another point that I forgot to mention is that, when the barrel is fully
down, the bottom of the barrel isn't supposed to lay in full contact with
the curved part of the frame. CORRECTLY fitted, the link should
be holding the barrel just barely off the curve...about the thickness
of onion skin. Very few late production pistols do this, and the barrel
lays in the curve. It doesn't seem to hurt anything, so it's probably the
result of the manufacturers finding yet another shortcut in the assembly.

At this point, it's mainly trivia...but one that many don't realize.

Keep it goin'!

Tuner

Old Fuff
December 28, 2003, 03:08 PM
Perhaps I should explain that in a stock .45 1911 or 1911-A1 pistol with a standard GI barrel and link the slidestop pin and lower lug do not play any part in camming the barrel into a locked position. This is left entirely to the link, and when the slide is in battery the barrel “floats” to some degree at the breech end. Prior to the late 1950’s there was only one barrel configuration and one size link.

The development of using specially sized links and/or the lower lug on the barrel as a cam surface to position (or lock) the barrel into the slide while the pistol was in battery came about because military arsenals at Springfield and Rock Island, as well as several well-known civilian pistolsmiths, were trying to develop the best possible bullseye match pistol, not a service or personal weapon. The man in charge of most of these adaptations was an engineer at Springfield named Gene Taylor. He probably knew more about the Government Model .45 pistol then any man other then John Browning. At the time he had the full resources of both the arsenal and Colt’s behind him, and I was fortunate enough to learn a lot of what I know from him.

Correctly fitting a “match grade barrel” to an individual pistol (and once fitted a barrel does not usually interchange between different guns) requires special tooling, fixtures, and gages – most of which are available from Brownells. It also requires knowledge and expertise. None of this is beyond the capability on an ordinary gun owner with basic mechanical skills, but in terms of doing one – or several guns – it is overly expensive in terms of the learning curve and equipment costs.

That said, I believe that most of the members of this forum are more interested in the Government Model as an optimal personal weapon, not as a match pistol. The requirements for both are different. Where the match gun is primarily designed to offer the best possible accuracy a weapon should emphasize operational reliability – under any circumstances and in any environment.

Tuner’s explanations concerning the proper fitting of a slidestop cammed lock-up are, in his usual fashion both detailed and correct. Anyone can benefit from an understanding of what happens, and why it happens. One may also notice that things are not as simple as they might first seem, and that a small error in fitting may have some short or long term effects in the way the pistol functions (or doesn’t as the case may be). This knowledge may help one diagnose the cause of some malfunctioning and provide a clue as to what corrections should be made to cure it. However simply disassembling the gun and going to work may result in more and possibly worse problems. There is no substitute for experience. Anyone who might have to use their pistol as a weapon should never forget this.

bigjim
December 28, 2003, 05:46 PM
Thanks for the input Old Fuff,

That really is the rub isn't it? I understand what you are saying in regards to needing experience to do these things right. The trouble is no one is born with this knowledge. Even the worlds best smiths had to learn at some point.

I do think these forums and the kind of information we are generating in these clinics could make that learning curve less painful for some.

I for one will be happy to learn things from you guys as opposed to getting a bloody nose learning by myself.

If it serves no other purpose it can help us recognize when we are being BS'd by a pistol smith that isn't.

romulus
December 28, 2003, 06:43 PM
Another point that I forgot to mention is that, when the barrel is fully
down, the bottom of the barrel isn't supposed to lay in full contact with
the curved part of the frame. CORRECTLY fitted, the link should
be holding the barrel just barely off the curve...about the thickness
of onion skin.

What happens if the barrel is completely off the frame barrel bed, meaning more than merely an onion skin's worth of difference? After reading Kuhnhausen I figured that this point of contact had to be exact. If the gap is significant, what are the repercussions?

Thanks

1911Tuner
December 28, 2003, 06:52 PM
Old Fuff has nailed me down again.:D He's made a point about the
barrel link that, looking back, he tried to make once before, but I didn't
see it. Haste, and my habit of checking these posts in the wee hours
before I've poured enough coffee down my neck to be able to see.
In fact, I had a rather heated discussion with Jim Keenan on this very
point about a year ago. He was referring to fitted barrels, while I was
taking Fuff's point of the barrel pivoting on the link.

Yes. Up to a point, the barrels rode the links instead of camming into lockup via the lug/slidestop pin, BUT...when in vertical lock, the link should be flush with the barrel lug. That some weren't was likely either the result
of hasty assembly, or a misunderstanding of what the return to battery impact would do to the tips of the lower lug feet instead of in the stronger
area of the radius. Most of them didn't stand above flush, and was the result of the bottom lugs being in-spec or very close. Most production pistols barrels today ride the link to a point just prior to lockup, and some are partially supported by the link, but this condition will contribute to early failure of the link, the linkpin, and its hole in the lower lug. Given enough use, it can even wallow out the slidestop pin hole.

Keep in mind that,in the beginning, these pistols weren't designed with
100,000 rounds in mind without arsenal attention. Even 50,000 would
be stretching it. Most were rebuilt much sooner.

When the link is above flush, the innacuracy comes from having only one
narrow point of support. When the bullet engages the rifling, it causes
the barrel to torque, and if there is a fairly loose fit at the hood, it would
rotate. Unless it rotates exactly the same from shot to shot, the groupimng
potential opens up. A flush link with full support across the lug works to limit that rotation somewhat, depending on how much difference there is between the size of the slidestop pin and the hole in the link. Anyone who has fired a rifle from a sandbag very much can attest to the effect that canting the rifle has on groups. Since most pistols prior to the end of WW2 were ordnance spec with more generous tolerances than their pre-war counterparts, the above-flush link's effect would be greater. This, along with hasty arsenal refurbishes, doubtless contributes to some of the accuracy issues with WW2-era GI pistols.

One final point on the barrel linkdown timing. If the barrel unlocks just at
the right time, when pressure is low enough to allow the case to move
easily, but with enough residual pressure left in the chamber, the pistol will
function very well without an extractor. After playing with this for a while, I've come to the conclusion that this is more likely to happen when the
barrel timing is a little late. Tming the linkdown a bit earlier with a.003
shorter link returns the gun to needing the extractor to get the case out of
the chamber. That's less than the thickness of a sheet of notebook paper.
Amazing what a difference such a little dimension can make.

Cheers! I promise to read more carefully in the future. Still wonderin' if
Old Fuff is gonna reveal his true identity.:scrutiny: I think he's somebody famous.:cool:

Cheers!
Tuner

1911Tuner
December 28, 2003, 07:03 PM
Romulus asked:

What happens if the barrel is completely off the frame barrel bed, meaning more than merely an onion skin's worth of difference? After reading Kuhnhausen I figured that this point of contact had to be exact. If the gap is significant, what are the repercussions?

Possible feeding problems, depending on how far it's up off the bed,
and how far forward of the frame's ramp the leading edge of the throat is.
If it's high enough, the bullet nose hits the edge instead of making a smooth transition into the throat. Sounds like the lower lug feet are too long, or there is a burr on the side(s) of the lower lug that's stopping the barrel from going to bed. Also a slight chance of the link's pin not being centered in the lug, and one side is making contact before the barrel is down. Hard to say without seeing it.

Have a look and get back to us.

Tuner

romulus
December 28, 2003, 07:53 PM
ahhh...of course, the gap between ramp and barrel will increase. I can fit a piece of a business card in there and still cycle the gun without compressing the card (a Norinco) Having said that, I never had a failure to feed...

1911Tuner
December 28, 2003, 08:06 PM
Romulus said:

) Having said that, I never had a failure to feed...

Hey..If it ain't broke, don't fix it I always say.:cool:

romulus
December 28, 2003, 08:29 PM
If it ain't broke, don't fix it I always say.
Yes indeed. Nonetheless, I always strive to understand the theory, the reason behind things, not just the effect. So I learned a valuable lesson. Thank you.

Delmar
December 28, 2003, 08:42 PM
My oh my! Tell ya what, guys-if Delmar ever wins the lottery, several of you are going to get seriously PM'ed to form a company to build 1911's the RIGHT way.
There is no doubt in my mind that there are enough people on this forum with the knowhow to build a 45 so correct that the custom builders would be scrambling to compete!

Yeah, I know-its probably not going to stay solvent for long. Sort of taking a large fortune and turning it into a small one:what: Heck-nobody lives forever!

Jammer Six
December 28, 2003, 09:19 PM
If I understand what you guys are saying, match pistol "wedge" (my understanding) themselves into vertical lockup using the profile of the two feet of the barrel lug bearing on the slide stop pin. This is more stable, tighter, and more predictable than riding the link, which must be looser and allows the barrel to "wobble".

Carry weapons, on the other hand, ride the link.

You guys didn't say anything about why, but I've been thinking about it.

It sounds to me like this: if any goo, gunk or grit got into the lugs or onto the slide stop pin, if the fit was real tight, it could be enough to prevent the barrel from wedging into place, and stop the weapon from going into battery.

Is that the reason carry weapons aren't fit to ride the lugs?

Jim, I haven't found your vector theory in Kuhnhausen. Where is it?

1911Tuner
December 28, 2003, 10:04 PM
Jammer asked:

It sounds to me like this: if any goo, gunk or grit got into the lugs or onto the slide stop pin, if the fit was real tight, it could be enough to prevent the barrel from wedging into place, and stop the weapon from going into battery.

Yep. A tightly-fitted match-grade pistol is more sensitive to dirt. Accuracy
comes with a price, and reliability under adverse conditions is the cost.
Bullseye pistols are the most tightly fitted. Action-game guns are a little
less so, and are less dirt sensitive. Defensive pistols, or pistols built to
save the life of a Marine on Saipan or an Airborne Ranger on Omaha
Beach are the loosest.

It's entirely possible to have a good lower lug to pin fit without
sacrificing reliability, it just won't deliver match-grade accuracy.
I have a few carry pistols and range beaters that have zero vertical
movement at the hood, but will run through over 2,000 rounds reliably
without cleaning. The main thing is to get the pin to bear evenly on both
lugs. If there's a tiny bit of vertical play, the pistol will be accurate enough
for its intended use. As long as the firing pin strike is well-centered, it
won't really hurt anything other than causing the pistol to shoot a little high.

There are also other factors that determine accuracy. Hood to slide fit
to limit barrel rotation. Locking lug fit to the recesses and lugs in the slide
to limit fore and aft play in the barrel. Bushing to slide and barrel to bushing fit. Headspacing and barrel crown...All these add up to create
accuracy, or degrade it, as the case may be. Slide to frame fit seems to have the least effect on accuracy or the lack of it, unless the pistol is
mounted in a machine rest.

Cheers!

Tuner

Old Fuff
December 28, 2003, 10:11 PM
BigJim:

In the past those who built Colt Government Model pistols at the factory served as apprentices working under master “smith’s” supervision. The skill of these workers was such that when the Springfield Arsenal wanted to produce the pistol Colt couldn’t provide a full set of drawings – because they didn’t have any! They didn’t need them “in-house” because their workers used a combination of skill, experience and gages. In the end the engineers at the arsenal disassembled a number of Colt-manufactured guns, measured the parts, averaged the important dimensions, and over a period of about a year made their own drawings. The young (and carefully chosen) apprentices didn’t start out doing perfect work, but they also didn’t do any work on commercial or government products without being carefully watched and checked – and it was sometimes years before they started doing work on their own.

During the late 1950’s and forward the military services trained individuals to build match rifles and pistols as part of a larger Marksmanship Training Program. Many of these men would later play a large part in building guns for the various “Combat” games that became popular as well as producing true weapons. Again they were the product of a system that produced what might be called “gun-makers with a formal background.” A smaller number learned their trade by attending schools with gunsmithing programs.

All of these examples shared at least one common thread. They were in one way or another, trained to do the work they did, and sometimes spent years in the learning process.

Tuner:

The Old Fuff is indeed famous, but only in his own ego.

bigjim
December 28, 2003, 10:13 PM
Tuner,

If you take a 1911 pistol and shoot it by hand or shoot from a ransom rest, which method will produce a better group?

I know on the surface this seems like a dumb question. But I suspect there is more to it than may meet the eye.

Jim

1911Tuner
December 28, 2003, 10:37 PM
Jammer, here is a good link with pictures that describes what Jim is talking about. The pictures will take a few minutes to download, and a few points
aren't accurately illustrated, but it's still a good visual aid.

http://www.m1911.org/locking.htm


bigjim asked:

If you take a 1911 pistol and shoot it by hand or shoot from a ransom rest, which method will produce a better group?

I know on the surface this seems like a dumb question. But I suspect there is more to it than may meet the eye.

Depending on a few things, it's entirely possible to shoot a tighter group
without the machine rest. I'll have to get deeper into it in the mornin'...
Beddy-bye time. Been a long stretch since 3 this A. M.

One hint: If the barrel is fitted well to the slide, but the slide to frame fit
is loose, a good marksman can outshoot the pistol fired from a Ransom rest.

Think about it. See the gun. BE... the gun, and it will come to you.:scrutiny: :D

Nitey-nite!

Tuner

Old Fuff
December 28, 2003, 10:39 PM
Jammer:

The answer to your question isn’t easy because so many companies – as well as individuals – are making Colt style pistols. Each uses one or more methods of fitting a barrel, and we haven’t discussed all of the possibilities, just the popular ones. Many employ the word “combat” to the point where it has become meaningless. Thus you have so-called “combat guns” that have match-fitted barrels that are set up to lock by being cammed by the slide stop pin and lower barrel lug. So what happens if too much dirt and fouling gets into a critical area? Well unless the gun maker/builder has taken this into account and built in some clearance the pistol will probably jam – just as you suggested. This is one reason that today’s buyers expect to fire several hundred rounds through a gun to “break it in” before it’s really reliable (?) when in earlier years this wasn’t necessary.

However, if a pistol that uses the camming system is correctly adjusted to take fouling into consideration you have the best of all worlds.

Unfortunately only a few companies/people who are involved in making guns understand what is truly necessary to make a weapon rather then a toy.

1911Tuner
December 29, 2003, 08:17 AM
Amen and amen. In his usual fashion, Fuff has cut through the BS and headed straight for the heart of the matter. Sadly, the manufacturers of the 1911 pattern pistol know that, for the most part, they're building a toy. Many of them set the guns up far too tight to be serious weaponry. Whenever I hear of a warranty station telling an unhappy customer to shoot a thousand rounds to "break it in", I shrug my shoulders.

They do this for three reasons, as far as I can determine...none of which
is valid for a pistol that is to be used as a weapon.

1...The customer believes that a super tight pistol is a better pistol. I
think this stems from the complaints coming from the flood of GI pistols
that began showing up. Worn out, poorly rebuilt...many of them were
parts guns that were slapped together and pawned off as "genuine".

2...To wring maximum accuracy from the guns...which may or may not work, again depending on the skill of the builder or the QC of the manufacturer.
Again, complaints about the "innacuracy" of the .45s is to blame. The
plain truth is that a true ordnance-spec pistol isn't a loose rattle bucket.
I've had the privelege of handling a few pre-war 1911s and 1911-A1s
that were in pristine condition. There was very little play in the slide to
frame fit. No vertical barrel play...Barely enough fore and aft or
rotational movement in the barrel to be able to detect, and the barrel to bushing clearance was .003 inch or less. The pistols were accurate and completely reliable. Military and commercial Colts were all built the same
way, by the same people.

During the watershed of WW2, it was determined by engineers that some of the tolerances could be loosened up an little without compromising the
functional reliability of the guns, and it became standard. This wasn't done
to make them less jam-prone in adverse conditions...It was to speed up
production, and to allow "Rosie the Riveter" workers to assemble guns that were needed in a hurry. The "Drop-In" part was born.

3...Because the US Government hasn't accepted any contracts for the pistol since 1945, and the reliability of the pistols isn't all that critical
any more. Colt built post-war commercial models for a while from the
parts left over from the GI era...but those are long since gone. They
continued to build them using the same correct materials for a while longer, but as the cost of production escalated, profit margins began to dictate how the pistols would be built. Investment cast, and later, MIM small parts began to surface. Small parts were no longer made in-house, but contracted to outside vendors. "Your equipment was supplied by the
lowest bidder." So sayeth Gunny.

Enter the Custom Pistolsmith. He will build to your specifications. He is
the bastion of days past. He will build it "Right, not Tight" for those who
understand...or he will build it dead tight, as you wish. This is why the
really good ones spend time discussing your pistol order. They ask
pointed questions to determine what it will be used for. Strictly target
or defense/carry...and then build it the best way for the intended role.

Some few will build them all tight, and advise you to break them in.
Okay...but there is a simple and effective method of speeding up the
break-in process on a pistol that's too tight.

Jim Keenan and I understand. Jim is a pistolsmith, while I am more of
an expedient field armorer...a troubleshooter and repairman. I'm
beginning to feel that Old Fuff is the sleeper of the group. He understands too, and I think he knows more than he's revealing so far. No doubt that he and Keenan would smoke me in a Custom Pistol contest. 90% of my experience has been salvaging, rebuilding, troubleshooting, and repair. Got a functional problem? I'm your boy. Want to talk about custom building or accuracy tweaking? I have to defer to those two.

Jim K
December 29, 2003, 10:16 PM
Hi, Jammer Six,

It's not "my" "thrust vector" theory, it is Kuhnhausen's. I don't have the books at hand right now but it is in the section where he shows the operation of the pistol and the drawing depicts the bullet exiting the barrel while it is in full lockup and the link is still fully forward. He says that the barrel doesn't move until the bullet exits and attributes this to a "thrust vector". He is not a physicist and I suspect he simply couldn't handle the concept of recoil.

I like the books, and use them frequently. They are excellent works on tuning and maintaining the 1911 type pistol. But it would be nice if he understood how the darned gun works.

Hi, 1911tuner,

Thanks for the kind words. But unlike some of the folks here, I have not devoted my time exclusively to the 1911, just working on them as part of the work of a general gunsmith. But I did learn what makes the gun tick (see above on another JK) and turned out a few very nice ones, or at least I had the customers fooled.

Jim

1911Tuner
December 30, 2003, 07:00 AM
Howdy Jim. I think you're bein' modest.

Jammer isn't tryin' to box you in on the Thrust Vector thing. He's just tryin' to find it. He and I have been working on a hammer followdown issue that he had after a hack polished everything before he got the gun. From what he tells me, he's got it fixed, and is on a search for more knowledge.

Jammer, if you didn't see the link that I pasted to an earlier post, I'll
redo it so you can open the page. Good cutaway view of the pistol,
though some of the pictures aren't completely accurate, and a description
of the Thrust vector that Jim is referring to. I'll go get it and put it at the bottom of this reply on an edit. The pictures take a few minutes to
download, so be patient.

Pay particular attention to the picture and description of the link's function, and look closely at the picture in Locking Phase A. It shows a properly fitted link in relation to the front radius of the barrel lug. Here, it appears that the barrel is lightly riding the link, and pivoting upward on it, though part of the load is also borne by the lug itself. This is the point that Jim and I had a heated discussion over about a year ago. He was talking about a fitted barrel lug, and I was talking about an Ordnance setup. When we realized that we were comparing apples to oranges, we arrived at a Modus Vivendi, and have had many discussions via E-mail ever since.

Most production pistols ride the link much more than is shown, until full
lockup, at which point the link is flush..or nearly so...with the bottom of the
lug as shown in the next frame. It can be slightly below flush, but it shouldn't be ABOVE flush. Some are very slightly above flush, and I think that this is what Fuff is referring to as the viable link-borne lockup. I'd
assign a maximum of .003 inch above flush, but would prefer that it be
dead on if it can be arranged. At any rate, below flush is preferable in order to prevent putting undue stress on the link and pin. The link-borne
lockup doesn't seem to hurt anything in the short term, but on a heavy
use pistol, it can cause some problems.

If I have a situation where I can't find a link to make me happy, I'm not above elongating the hole slightly to get the fit that I want. Again, .003 inch maximum for this kind of "Jerk Engineering" ..and always at the top of the hole. Removing metal from the bottom will delay linkdown timing. At any rate, the desideratum is to match the link to the lug's radii whenever possible. The other route is to weld and re-cut the lug...a tedious undertaking, and not one for the inexperienced.


http://www.m1911.org/locking.htm

Cheers!

Tuner

Jim K
December 30, 2003, 11:08 AM
Hi Jammer Six and guys,

No problem with asking, and I apologize for the delay in responding. My house has been a bit disrupted for the last few days with visitors, and my Vol 1 of Kuhnhausen is still among the missing. But the "thrust vector" mention is found in Vol 2, Page 42, Figure 29.

The writer (Kuhnhausen?) seems to be under the impression that the drag of the bullet in the barrel keeps the slide and barrel locked until the bullet exits and then somehow the unlocking occurs. I can't really follow the explanation because it is simply wrong. Figure 30, showing the slide and barrel fully locked after the bullet exits is also wrong, as are the comments explaining this.

What really happens is both simpler and more complex, but first, one has to accept the Law of Conservation of Momentum*, which says that any movement of a mass in one direction creates an equal movement in the opposite direction. This is just a better way of stating Newton's third law of motion, but the rule is simple: Mass times velocity in one direction equals mass times velocity in the other, or MV=MV. The bullet is low mass but high velocity, the barrel-slide unit is high mass but low velocity, so they balance. It is the bullet movement forward that causes recoil backward and shoves the barrel-slide unit back. If there were no frame, the two parts would never unlock and they would stay in motion until gravity and air resistance caused them to fall to the ground, still locked together.

But there is a frame, and a slide stop, and a link. So the link drags the barrel out of engagement with the slide, letting the slide continue on its own momentum to compress the recoil spring, cock the gun, and extract and eject the fired case. The energy stored in the recoil spring, combined with the "bounce" of the slide against the recoil spring guide (backed by the frame) then returns the slide to battery, chambering a fresh round on the way.

Side note: When a buffer is inserted, it absorbs some of the energy of the recoiling slide, but does not return any, so there is no "bounce"; the result can be failure of the slide to return to battery properly.

The pressure generated by the burning powder does not itself operate the gun. It moves the bullet and it is that movement and its opposite recoil that operates the pistol. If the barrel is blocked so the bullet cannot move, there is no recoil and the pistol will not operate.*

But the gas pressure alone will not open the action any more than gas pressure will open the action on, say, a Mauser rifle. The slide and barrel are locked just as firmly as the bolt on the Mauser and must be unlocked by an outside force, which is the link.


*Most folks have no trouble simply accepting the Law of Gravity and don't go jumping off buildings, yet I have been asked to "prove" the Law of Conservation of Momentum and have been flamed for not accepting Kuhnhausen's explanation. I respect Kuhnhausen, although we have never met, but I don't believe his books were written in fire on stone tablets and my own copies were delivered by USPS, not Moses.

**I have described doing this elsewhere and see no reason to repeat it, except to say that this kind of experiment must be carefully prepared and should be done only by those who fully understand the situation.

Jim

Jammer Six
January 1, 2004, 11:47 PM
Jim, Tuner, Fuff, everyone, thanks.

I was in B.C. for the new year, and now I have to go study drawings and read Kuhnhausen.

Thanks again. I'm sure I'll come up with more questions. It's what I'm good at.

Happy New Year, everyone.

romulus
January 2, 2004, 01:00 PM
Given all the attention given to the link in this thread, especially the part about longer links exerting upward pressure, I got to thinking about the Dwyer Group Gripper that I installed in my dad's 1991 A1. Obviously the link is working to cam up the barrel deeper into the upper slide lugs...It also, I would guess, work opposite to Tuner's understanding that a hole should be slopped only at the top, but I can't see the GG working unless there is slop at the bottom of the link hole (lower hole) to allow the notched link to ride up and allow the barrel lugs to "reach" the slide.

I would then guess that the GG is mode of operation is based on a faulty principle that would necessarily end up, as noted, with possibly catastrophic results to the barrel...I'm seriously thinking of swapping out the GG (which my dad has barely shot) and re-fit the barrel at the feet (weld and recut.)

Also, can the group gripper, working under positively applied force, affect the aforementioned dwell time, or the spring force relatively insignificant compared to the force of the recoil? meaning, how timing sensitive are these guns really?

Thank you again

1911Tuner
January 2, 2004, 01:48 PM
Howdy romulus. I THINK I knw how the Dwyer thing works...I've never
used one or even seen one...but if I'm not mistaken, it works by forcing the
slidestop pin more firmly into the rear radius of the lower lug, using pressure from the recoil spring. Since the bottom of the lug isn't dead
horizontal, but at a slight angle, this would force the barrel upward into
a tighter vertical lockup.

Jim Keenan or Old Fuff may be able to give you the straight of the Dwyer's operation...or to correct me if I'm wrong.

Guys?

Standin' by...
Tuner

Old Fuff
January 2, 2004, 07:46 PM
Ah yes, Mr. Dwyer’s little “Group Gripper,” during my misspent youth I knew it well. It has a modified recoil spring guide with a very stiff flat spring inside. At the back end the spring has a sharp bend that faces upward and fits into a notch cut into the bottom of the link. The idea is that the spring pushes on the link and so moves it (and the barrel) upward when the pistol is in battery. In practice this won’t happen unless the link’s lower hole is elongated. What it does do to some degree is support the link, and therefore the barrel, which may, or may not affect the pistols accuracy.

I have put them in some pistols and thereafter accuracy improved – at least to a small degree, while in others there was no improvement whatsoever. It is one of the many gadgets on the market that sometimes help, but not often. So far as I can see that don’t hurt anything, and the inventor has made a lot of money off of it. The only time I would recommend using one is where, for whatever reason, the pistol itself cannot be modified in any way that prevents it being returned to its original condition. If accuracy is you’re goal, properly fitting a match grade barrel is a much better idea. If maximum reliability in uncertain (but probably harsh) environments is what you want leaving the pistol in a “service/stock” condition may be a better idea.

Tuner, you have no idea what you’ve missed …….

1911Tuner
January 2, 2004, 07:53 PM
Old Fuff said:

Tuner, you have no idea what you’ve missed

Yeah...I thought that thing looked like a gimmick, and thus avoided havin' a
go at it. Now, there's a few other things that I can't say that about...the
few that slipped in under my radar.:rolleyes:

yoky
October 16, 2004, 05:30 PM
My friend has a serious problem. After 1500 round through His Norinco he changed recoil spring. Next shooting barrel link was broken in part around slide stop. He has changed link and situation was the some. We have measured if the slide stop is sitting OK in link and in the barrel lugs we haven’t seen any problem. Has anybody what is wrong? Only what we have seen is shorter gap between barrel and feed ramp normally is about 0.8 mm and measured is about, 0.5 mm. We did not find out any problem. My friend is in conviction that it was caused by stronger recoil spring. Can you help us?
Thank you in advance for updating me
yoky:mad:

Dave Sample
October 16, 2004, 06:23 PM
http://pic11.picturetrail.com/VOL368/953404/1874536/51106951.jpg

Here is another way to do it. This is a Star 38 Super barrel that does not need a link. I do not use long links or short links. I leave these for the very clever guys to install. I always fit a barrel up to a .0278 or Number Three link. The link fit is very important , in my opinion, and I have seen terrible things done to them in the past. I have seen link pins turned into crankshafts by incompetent people. Note the barrel is marked 38 since I re-chambered it from a 9mm. It will shoot either, but pretty much destroys the 9mm cases. Also note the Armorers Mark up front. This way we know who did what.

Old Fuff
October 16, 2004, 06:52 PM
Ah ... Dave.

The 9mm Luger cartridge has a tapered case that's .392" at the base, and .380" at the front.

The Colt .38 ACP/Super has a straight case that measurers .383" at the base and .382" at the front.

The Spanish were well known for some rather interesting chambers, but the one you made must be even more so ... :what:

1911Tuner
October 16, 2004, 06:54 PM
Howdy Yoky,

When a link breaks, it's most often caused by either the impact surface in the frame being set too far rearward or the barrel lug sitting too far forward...or both... and the barrel's rearward movement as it unlocks is being stopped by the link instead of the frame. It indicates a bad frame or barrel...or both.

Replacement is usually the simplest and cheapest way to go. Unusual for a Norinco to be that far out of spec, so it was probably a stack-up of tolerances between that particular frame and that particular barrel.

It's also possible that a short link is a player...but that little bug usually gives warning that something is wrong. Turn the pistol upside down and hand-cycle it. If the slide stops short or feels like it hits a snag, you've got a short link...or at least too short for that particular gun, given the tolerance stacking that seems to be there.

It gets worse...

If the link gives way before unlocking is complete...and it usually does... the lugs are usually damaged by the one crash, and probably will shear off or crack soon after, even if the problem that broke the link is corrected. The slide lugs could also suffer some damage.

Check for damage to the locking lugs at the front. If they are rounded off or they have a burr along the top edge at the front...known as flanging..
the slide has whacked the lugs. If the lugs on the barrel or ion the slide have a "stepped" appearance...same thing.

Look at the lower lug at the backside. If there's a dent about halfway between the junction with the barrel and the bottom of the feet, it was hit pretty hard when the barrel got caught between the frame and slide with the locking lugs still engaged.

Hard to tell if the damage was light or heavy without seeing the gun...and also hard to determine if a longer link can be used to keep it from happening again.

Wish I could tell ya more...

yoky
October 16, 2004, 08:02 PM
Tuner
Thank you very much you give to me another idea what can be wrong. We will inspect the gun closely as much as possible. I have to try to post some pictures. I understand it would be difficult to say exactly what is wrong without having the gun in hands and without see it in nature for analyses.
Together with pictures I try to find out more details about the gun.. This is not first time you have helped me
Thank you very much, and your help is highly appreciated. Now thinking about the problem I guess you are right really something is out of spec. I will inspect another Norinco for comparison, barrel frame etc.
Best regards
Yoky

Dave Sample
October 17, 2004, 04:52 PM
Ah, Old Fuff. You did not pay any attention to what I said about this Star Super Modelo B. This chamber started out in life as a 9mm. I re-chambered it to 38 super with a Nonte' Reamer so that it now headspaces like a 45 ACP and therefore, the mouth of the chamber will take a 9mm and the extractor (external) will hold it against the breechface while it lights up. I know this is not the ususal way to go, but since you know everything, you should know that these Stars were meant to take either a 9mm barrel or a 38 Largo barrel with matching recoil springs and they use the same magazine. The basic gun is the same for both calibers. In 38 Largo, it's a Star AS and in 9mm, it's a B. I know you don't read much of what I say, and I never read your long winded disertations, so this is not for your benefit, but rather , for the others on this forum that wish to improve their knowlege of this Spanish Steel. I have done at least a dozen of these barrel and spring conversions , so I know it works.

http://pic11.picturetrail.com/VOL368/953404/1874536/51107179.jpg

This is what it feeds like greased green goat grunty now.

http://pic11.picturetrail.com/VOL368/953404/1874536/51106917.jpg

No Stem Bind here. Note the loaded chamber indicator at the upper rear of the port. Nice feature.

A.V.Gregory
February 26, 2009, 03:34 PM
New .278 link installed to replace amuch worn link.with spring anr barrel bushing removed , slide in battery the barrel is slanted down, trigger functions normaly and hammer will fall.Installing bushing pushes the barrel up and causes the slide out of battery.no trigger function and hammer won't fall. Is the link too long or too short?

rcmodel
February 26, 2009, 03:58 PM
Well, I do my best link fitting with the barrrel bushing in the slide!

However, it seems like yours is too long.

If it was too short you couldn't get an assembled slide open all the way.

I'd suggest you get the Jerry Kuhnhausen book to learn all about it.

There is a lot of good information in this thread too.
http://www.thehighroad.org/showthread.php?s=&threadid=56380

rc

evert
March 22, 2009, 07:04 PM
Tuner, you say: "when the barrel is fully
down, the bottom of the barrel isn't supposed to lay in full contact with
the curved part of the frame. CORRECTLY fitted, the lug feet should
be holding the barrel just barely off the curve...about the thickness
of onion skin."

I have always fitted my pistols with a link that caused the barrel to hit both at the lug-feet and the bottom of the barrel at the same time, beliving that this will divert stress over a bigger surface than just hitting at the lug-feet.

You seem to be very well experienced in all the 1911 stuff you describe, and i belive you may enlighten me here as well?!

looking forward to you answer!

1911Tuner
March 22, 2009, 07:13 PM
the lug feet should
be holding the barrel just barely off the curve...about the thickness
of onion skin."

Not by the feet...by the link in compression. If I wrote that, it was an in-haste error and I'll need to go find it and correct it.

Since that ideal is only rarely seen, it's not a critical necessity. As long as the barrel hits the vertical impact surface first, with a little clearance between the barrel and frame bed...curve...it's good to go.

Hitting the bed first, or even at the same time places stress on the link...slidestop crosspin...lower lug...and barrel. Most of the time, it stretches or breaks the link, or causes the link pin to loosen...but I've seen lugs pulled clean off the barrel, with a few cracking through to the chamber.

saltydog452
March 22, 2009, 08:33 PM
If the link is correct (?) with the upper lugs/slots and lower lug radius/cross pin, and there is contact on the frame bed, as evidenced by Dykem movement on bed and that portion of the lower barrel that contacts the bed, it would seem that the bed would need to be lowered a bit.

(Long, drawn out sentence structure, but I did not know any other way to string it together.

If true, how?

Half round files do not match the bed contour.

Thanks,

salty

1911Tuner
March 22, 2009, 09:50 PM
If true, how?

The proper method is with a ball end mill of the correct radius.

havoc7usmc
March 23, 2009, 03:53 PM
OK. You gentlmen need to get together and publish a manual that we could buy. PLEASE.

saltydog452
March 23, 2009, 05:11 PM
I have printed dang near everything that Tuner has typed.

About two reams worth.

No way to organize/index it though. At least nothing better than the 'search' feature on these two forums.

On the bright side, if the ownership/archive issues of THR get all wrapped up and go down in contentious flames, I have whats left of my memory and two large three ring binders of 1911Tuner.

Thanks Tuner.

salty

Jerry Keefer
March 29, 2009, 09:33 PM
Salty Dog;

Tuner's right, that is a method...but ball end mills of that radius will need to be specially ground, (= expensive), and your setup must be very rigid due to the shearing forces of a ball mill, so you will need a very good fixture.
I prefer a contoured wheel on the surface grinder. You can dress any contour (radius)you can imagine. Plus the grinder is a precision, finesse, machine that will work to the millionths...Finally, I remove the stock from the bottom of the barrel radius with a contoured wheel. Barrels vary widely from one manufacturer to another, and the frame will stay unaltered for the next barrel fit up in the future...

Jerry

krs
April 1, 2009, 06:15 PM
Nice recovery Tuner!

Considering that Evert called you on something you wrote over FIVE years ago. :D

1911Tuner
April 1, 2009, 06:45 PM
I still haven't found that part about the feet holding the barrel off the bed. :scrutiny:

krs
April 1, 2009, 07:33 PM
I think it's post #18, but I'm not sure that's what you meant. It was like yesterday though so I'm sure you can clarify it for him :)

Nope it's #20

1911Tuner
April 1, 2009, 08:33 PM
Found it! It was #20 and...it was written up wrong. I corrected it for future reference.

I musta been in some kinda rush that day...

Anyway...The barrel should be held off the bed by the link in compression...but I've seen very few that did...even carefully hand-fitted pistols. Most will drop the barrel all the way to the bed after stopping on the vertical impact surface. The important thing is that the barrel doesn't hit the bed first or at the same time. As long as it stops on the VIS and drops to the frame afterward...it's good.

Thanks for the heads up on that.

saltydog452
April 1, 2009, 10:47 PM
Mr. Keefer,

I don't have anything more sophisticated than a pot metal vise and a few worn out files.

Files do not cut well when drawn backward. In my case, that may be A Good Thing.

I do get curious though.

The link and upper barrel lugs and slide slots was tough enough for me to get my head around, but when the VIS and frame bed get added to the mix, I do get more confused than usual.

salty

1911Tuner
April 2, 2009, 07:54 AM
when the VIS and frame bed get added to the mix, I do get more confused than usual.


It's not complicated, Jerry. The hard part is trying to describe in detail and simple function via the written word. Sometimes that gets tough, especially when ya try to juggle 5 different things while ya bounce ack and forth between the daily scoot and the keyboard.

I'll try to do it in as few words as possible...

When the slide draws the barrel backward, the link swings through a short arc. That arc is necessary to give the bullet time to exit so the breech can open safely.

When the link reaches the limit of its arc, the barrel...still moving rearward...starts to pull on the link, and begins to swing downward on an even smaller arc.

When the upper lugs have vertically cleared the slide's lugs, the rear face of the lower barrel lug strikes the vertical impact surface...halting all rearward barrel movement...and the barrel drops the tiny amount remaining to the frame bed. This small amount clearance between barrel and frame bed is necessary to prevent stressing the link, slidestop pin, and lower barrel lug. It's not necessary to have a lot of clearance, as long as the barrel doesn't hit the bed before it hits the vertical impact surface. Even a thousandth of an inch is good, but I prefer to see a little more than that because as the bed and the barrel become carbon fouled...the clearance goes away, and the barrel then hits the bed at the same time as the VIS. While that isn't as destructive as striking the bed first...over time, it does overstress the areas mentioned...and can cause a premature failure in any of the included parts.

How soon depends greatly on how well the gun is maintained and how often it's cleaned. Clean it every 50 rounds, and you'll never have a problem. Be like me and clean it every 2,000 rounds whether it needs it or not...and you will sooner or later.

This is another reason that I tend to set my guns up a little on the loose side. Laziness. I don't like having to stop 2-3 times during a 500+ round range session to clean my gun.

Now then...You understand that when the barrel comes out of the slide, before it stops on the VIS...there must be a little clearance between the top of the barrel lug and the bottom of the slide lug. How much clearance that's necessary depends on how well the gun is fitted. A precisely built gun like Jerry Keefer builds can get by with less clearance than one that I build.

This clearance must be present even if the barrel is forced upward when it's fully linked down and on the bed.

Gravity will let the barrel drop enough to fool you into thinking that you've got enough clearance when you actually don't. A quick'n'dirty way to check for it is to whack the muzzle sharply with the heel of your hand and hold it back hard when it stops. At that point, the barrel is against the VIS and has linked down as far as it can go without gravity helping it. The slide is at the timing point for full barrel linkdown.

Now, check for the clearance. If it's there, you're probably golden.
If it's not...the barrel linkdown timing needs attention.

I know you're wondering how to know about bed impact before VIS impact...

Coat the bed or the bottom of the barrel with layout fluid. A sharpie marker will work. Assemble the gun. Whack the muzzle with your hand sharply about a half-dozen times and look at the coated area. If ink has been removed...even in spots...you need a little clearance there. If not...you're good to go.

saltydog452
April 2, 2009, 10:39 AM
Its good to see you Bud.

Thanks...again.

sd.

JSmith
April 12, 2009, 07:49 PM
Thanks for all of this.

I'm a long-time pistol owner, beginning with the Webley .455 breaktop I bought in '78 (subsequently sold in favor of something else.) All my pistols had been wheelguns until about two years ago; I saw a BEAUTIFUL Mark IV/Series 70 Government Model (blue steel, rosewood grips as shown here (http://www.coltsmfg.com/cmci/Series70.asp)) at a local dealer and had to have it. There was no way around it. I've since learned that owning a 1911 is like joining an extended family.

I appreciate the information here: I'm not even remotely a pistolsmith but the forum (and the Kuhnhausen books) have helped me understand my pistol as a machine, which is important to me for some reason.

byronroland
May 20, 2009, 12:24 PM
This thread is great! I am new and trying to work on a M1991 A1 Officers Model bought used. Shoots way low! Like 1' at 10'. Now way sights are at fault? Had original sights when bought, I changed to night sights, front .178 rear .209, Hoped to fix or help. Did little.

Now I start looking and find link that measures long (have not removed for accurate measure- but will). Did do some checking and feel it is about .020 too long. With slide stop pin in place, lot of wobble, pin guage checks of hole in link show .201 go and .203 NG. Hole measures .202 with calipers, so about a .2015 to .203 hole. Slide stop measures .199 OD (calipers). But the link hole does not match radii of the lug, not even close, eyeball says .020-.025 proud of the radii. With slide stop assembled to loose barrel link, no match of radii of barrel lug to slide stop pin. Gap of at least .030. Slide stop pin mates to very bottom of lug in uncut area! When assembled and closed, barrel is tight to underside of slide.

I may get the gun back to accuracy/point of aim by changing the link? Go to a .178 and work from there? Or, buy a set?

Appreciate any help!

larryh1108
May 20, 2009, 10:27 PM
All I can say is this is one, incredible thread. The years of experience here talking to us is more valuable than any class, course or seminar we can attend. My thanks to all the people who spend their precious hours of time typing here so we can all learn from you. Without the knowledge here, this would be just another bulletin board.

Also, this has spanned 5 years! Incredible!

Many thanks!

navyretired 1
December 21, 2009, 10:29 PM
Am I understanding this properly? If link is too long barrel doesn't unlock fully and causes what someone called "rolling locking lug edges" and I was taught was called flanging of barrel and slide locking lugs.

1911Tuner
December 22, 2009, 07:02 AM
and I was taught was called flanging of barrel and slide locking lugs.

Flanging is the result of straight-line peening from lug setback. Seen a lot in older pistols with softer steel, and often noted on barrel and slide lugs, along with a stair-stepped appearance on one or both.

Linkdown/drop timing issues generally radius the top corners of the lugs, although a light flange may also be present. The severity of the radiusing depends on how much of the lug(s) is still vertically engaged in the slide when the barrel stops on the vertical impact surface.

Harvey
December 22, 2009, 08:00 AM
Fascinating thread for the 1911 disciple.

From the experts here, kindly remark on the Dwyer "Group Gripper" hawked so prolifically by Wilson Combat.

Thanks.

::EDIT:: Pardon me. I see that the "Group Gripper" is addressed on page two. Never mind. I does seem to present a valid engineering concept, tho, if some elongation to the lower link pin hole is considered.

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