1911 barrel link fit.

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dahermit

New member
Awhile back there was a post about how to measure the fit a 1911 style barrel link. As I remember there were all kinds of posts in response but none answered the question.

I have purchased a new barrel for my Series 70 Colt Combat(steel frame) Commander. It did not come with a barrel link. Therefore, I would like to know how it is determined if the barrel link is the correct length for that barrel/frame. I will install the link and pin from the original barrel and would like a way of testing the function of the link.

I do not wish to buy any of the various books on the 1911 just for one procedure.
 
You can buy a little gizmo called a Group Gripper, which consists of a link with a step in it and a spring guide with a spring that fits the notch. When the action closes, the spring pressure pushes up against the link locking it into the breech. If you fit the barrel properly, the Group Gripper link will not cause excess wear, affect timing, or change the clearance on the lugs.
 
FWIW:

"The 1911 barrel link is a simple part, but not so simple to fit correctly.
The standard part is .278" center to center. Most new pistols come with this size.
So why are links offered in longer and shorter sizes? - The answer is because not every 1911 is made to the same exact dimensions.
Even manufacturing tolerances can result in the need for a slightly longer or shorter link.

If you see a worn link, in an unmolested 1911, chances are great a standard .278" link is the proper replacement.

A "tuned" 1911, a 1911 made up of various parts, maybe a replacement barrel or slide, and especially a 1911 tinkered with by someone not completely knowledgable about 1911's, could need a different size link.

To understand why a size other than the standard link is used, you need to understand exactly what the link does in battery, as well as when - and how - it pulls the barrel down and out of battery when fired.
Also, the relationship of the link length to the lower lugs and the frame.

Jerry Kuhnhausen has written what is considered by many to be the standard 1911 gunsmithing book called "The Colt 45 Automatic". It is one of two 1911 volumes he wrote.

Mr Kuhnhausen wrote a few pages complete with pictures describing the areas to be concerned about when considering a link length.

Mr Kuhnhausen does an excellent job of describing the hows and whys of fitting a barrel link to a 1911.
Spend a couple hours reading his book regarding fitting links.
Then when you understand all of the issues you can decide whether to tackle it yourself or turn it over to an experienced 1911 smith.
BTW - The quality of links, like all other aftermarket parts, varies from a stamped out POS, to a well made precise part. "

* * * * * * * * * * * * *

As explained/alludded-to, above, the reason there was no clear answer to the previous post is that it's a complicated job to understand and also to explain to someone who doesn't know about precision fitting.

You said that you "do not wish to buy any of the various books on the 1911 for just one procedure".

If that's the case, then just drop in a standard link, and take the chance of barrel lug or frame damage.

.
 
...As explained/alludded-to, above, the reason there was no clear answer to the previous post is that it's a complicated job to understand and also to explain to someone who doesn't know about precision fitting...
Click to expand...
I am a trained machinist who has considerable experience fitting parts into
assemblies within .0002 inch that are much more complicated (Ossur's Mauk prosthetic knee), than a 1911.
However, reviewing the information on the subject on-line, it seems that the reason that there is no clear answer, is that there are really too-few persons who understand how to do it, and much disagreement on that subject.
In my case, the only person who I knew that I would trust to do it (a young man who specialized in building custom 1911's), died from the effects of cancer. In my area, anyone can call themselves "gunsmiths", but most are hammer-mechanics who lack the skills.
 
You might want to PM Unclenick here on TFL, since 1911s are his area of work, and see if he has any recommendations for you.
 
as mentioned, the standard is .278. raising the link (longer) would improve the slide/barrel lug overlap (increase it) and improve accuracy. commercial guns run about 60-70% overlap. 100% would be the most accurate but likely cause the slide to rub the barrel and would definately alter the rear barrel face angle.
the angle can be adjusted as well as the feed ramp, so, no biggie there.
you can do hit or miss with different sized links and see how the gun runs and what happens to accuracy. (that's how i do it :o) or you can measure the overlap by lining the lug slots with clay and cycling the gun.
anything above 50% overlap is acceptable for average use (non-competition).
it's actually easier to do it than it is to explain it. :)
 
Thanks, I reviewed the information that I found on the subject posted on the INTERNET 1911 forums including Jerry Kuhnausen's drawings and explanation. I have a pretty good idea now how it works.
 
1911 Timing observations.

After reviewing the data etc., I have found on the subject of 1911 timing and link issues, I offer the following for evaluation:

Although some/most production pistols will "ride the link", somewhat, after the link unlocks the barrel lugs from those in the slide, the barrel feet (I wish they had named them "cams"), should ride on the slide release cross pin.

If that be correct, it is logical then that one should be able to determine if his 1911 is timed correctly by observing burnishing on the caming surfaces of the barrel feet as it rides on the slide stop cross pin. If the burnishing exists, and there is not other issues that would indicate too short or too long of a barrel link, it is likely that the timing and the link for that 1911 are correct.

Yea or nay? And why not?
 
Dahermit,

It is a chicken or egg problem. If the link lugs are correctly fit you will end up with a longer link than you will if they are not fitted. Same with tightening the slide to the frame, except the other way around; fitted will make for a shorter link. So, any barrel and frame fitting you do comes first.

Once you have the barrel and slide as fitted as they are going to be (not at all for some carry guns) you can fit the link. I always make my own links from oil hardening flat stock, but I have equipment for heat treating them. Assuming you don't have the opportunity to do that, I won't bother to describe it, and instead recommend you just get one of the kits of 5 links or so. Later, you can purchase a replacement for the one you wind up using to keep the kit ready for the next gun, or sell the others if you don't think there will be another.

To chose the right link, you put the gun together without a link. I do this with the slide stripped of all but the sights and the grip safety removed from the frame so I can verify that the disconnector is up and bridging the trigger to the sear when the slide is in battery. Next, push down on the barrel via the ejection port with your thumb while you let the gun go fully into battery. The thumb is to prevent the barrel to jumping up higher than the link lugs on the slide stop pin can push it or having it overshoot the back edge of the frame too far. It should now be at least partially engaged in the locking lugs (fully at the rear lug if it is fitted), and the disconnector working. Put a registration mark between slide and frame where the the firing pin stop will cover it up later (I just use magic marker and a scratch awl for that). Use a depth mic or the depth stem that sticks out of the back of the beam on your caliper to measure from the top of the slide to the top of the barrel extension (hood). Do this inside the barrel extension channel on the breech face in the slide for easy repeatability.

Next, put the middle size link in the gun and reassemble it. In battery, you want it to land where the registration marks line up and the barrel is at the same height you measured before. If the slide won't go forward all the way to the mark or the barrel is too far from the top of the slide, the link is too short. If it tends to go into battery hard, like it were being forced a little, or if it passes the registration mark, or if the barrel is up higher, the link is too long. Change links until you get it right.

There is no simple direct measuring system for link size that I am aware of? If the lugs are fitted and you keep the barrel out of the gun and just try links until the assembly pin hole swings into just the right place on the link lugs by eyeball, you will likely be close, but the other checks, above, will make you sure.

Note that if the barrel is fit up, the gun often needs a long link. If it is long enough, it is possible for two other problems to come up: One is that the barrel can't get all the way down into its cradle in the frame in counter-battery. To check this, you assemble the barrel to just the frame with the link and slide stop in place and push it back with your thumb. If the link is long enough, the back surfaces of the link lugs can hit the frame before the barrel is all the way nestled into the cradle. This leaves a gap and you can rock the barrel up and down in the cradle a little. In this case you need to file metal off the backs of the link lugs until the barrel can get all the way into the cradle in counter-battery. Otherwise, it can drag on the slide and increase wear and reduce reliability.

The other issue is a long enough link can cause the ramped bottom edge of the mouth of the chamber throat to overhang the feed ramp in the frame. That is bad for feeding, so you have to file the bottom edge forward, usually to about 1/32" forward of the top edge of the feed ramp, and re-throat it to get feed reliability.
 
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I am a trained machinist who has considerable experience fitting parts into
assemblies within .0002 inch that are much more complicated (Ossur's Mauk prosthetic knee), than a 1911.
Click to expand...

And the parts you are starting with are likely made to far higher tolerances than a 1911, even from a high end maker.

These guns were designed when hand fitting was not especially expensive, and precession machining was.
 
Although some/most production pistols will "ride the link", somewhat, after the link unlocks the barrel lugs from those in the slide, the barrel feet (I wish they had named them "cams"), should ride on the slide release cross pin.

If that be correct, it is logical then that one should be able to determine if his 1911 is timed correctly by observing burnishing on the caming surfaces of the barrel feet as it rides on the slide stop cross pin. If the burnishing exists, and there is not other issues that would indicate too short or too long of a barrel link, it is likely that the timing and the link for that 1911 are correct.

Yea or nay? And why not?
Click to expand...
The question has not yet been answered.
 
As you might guess, since the barrel maker doesn't know your exact final fit in advance, he has to make the leading edges of the link lug contour for the shortest possible link or he will create a jam. It is only normally the bottom ends of the lugs that are long for fitting. The link lug cutters for custom fitting operate on the premise that the barrel is locked up hard (there is a fixturing tool you buy that makes that so) and the cutter inserts into the slide stop pin holes and you just bring the slide and locked up barrel straight into it and stop cutting when the back of the slide is about even with the back of the frame (usually just a little short of that to allow for future re-fitting).

What the above means is, looking from the slide stop side, only the first (upper right) quadrant of the pin makes contact with the link lugs when the gun is in battery. Since the link is a pivot, if that straight-in cut is perfect diameter, and if there was no tolerance slop in the link hole, then the pin would never touch the link lugs at all until it came to a rest in that one quadrant. For the barrel to actually cam up along the link lug surface, the slide stop hole in the link has to be bigger than the slide stop pin to give it room to happen, and they normally are a little bigger.

So, in final position, the bottom edge of the slide stop pin hole in the link is one slide stop pin diameter from the 90 degree point on the link lugs as trued by the cutter. The extra couple thousandth in the oversize hole in the link are then obscured behind the lugs themselves.

To get a fit that is guaranteed to ride the slide stop pin all the way up into battery, you have to go to the old school method of weld build-up on the barrel link lugs and a hand-scraped fit that rounds the corner in contact with the pin. It is slow, but it is what we used to do. Some custom barrels have enough metal on them that you can scrape a fit that covers most of the range of the barrel unlock and lock-up without doing the weld-up, but it will be a mark-and-scrape operation to establish the pivot radius on the lugs. The standard military tolerance gun has plenty of wiggle room for self-adjustment, which is another way to make camming happen, but it doesn't usually drive tacks, either.
 
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Although some/most production pistols will "ride the link", somewhat, after the link unlocks the barrel lugs from those in the slide, the barrel feet (I wish they had named them "cams"), should ride on the slide release cross pin.
Click to expand...

If your particular pistol is in fact riding the link, it will not, in all liklihood, show the "cams" are riding on the horizontal lower barrel lugs and cross pin. In a link rider, the barrel will pivot and follow the link on link down, which will adversely affect accuracy. The vast majority of factory pistols ride the link.

If that be correct, it is logical then that one should be able to determine if his 1911 is timed correctly by observing burnishing on the caming surfaces of the barrel feet as it rides on the slide stop cross pin. If the burnishing exists, and there is not other issues that would indicate too short or too long of a barrel link, it is likely that the timing and the link for that 1911 are correct.
Click to expand...

Timing is determined by how and when the barrels rear vertical lugs are contacting the vertical impact surface (VIS) in the frame, or if the lower barrel breach is contacting the frame bed first. The second phase of timing is how much clearance there is between the upper barrel hood and slide during link down.

These links explain it much better than I can:

http://forums.1911forum.com/showthread.php?t=262344

http://www.schuemann.com/LinkClick.aspx?fileticket=jWUIcpla6NU=&tabid=67&mid=445

Depending on your particular pistol, if the timing is correct, the Schuemann article describes how to check for a properly installed link. Hope this helps.
 
If your particular pistol is in fact riding the link, it will not, in all liklihood, show the "cams" are riding on the horizontal lower barrel lugs and cross pin. In a link rider, the barrel will pivot and follow the link on link down, which will adversely affect accuracy. The vast majority of factory pistols ride the link.
Click to expand...

Then, the majority of factory pistols, being "link riders", are not functioning as designed, and the caming surface of the lower barrel lugs and the slide stop cross pin are not functioning correctly as intended by John Browning?
 
To get a fit that is guaranteed to ride the slide stop pin all the way up into battery, you have to go to the old school method of weld build-up on the barrel link lugs and a hand-scraped fit that rounds the corner in contact with the pin. It is slow, but it is what we used to do. Some custom barrels have enough metal on them that you can scrape a fit that covers most of the range of the barrel unlock and lock-up without doing the weld-up, but it will be a mark-and-scrape operation to establish the pivot radius on the lugs.
Click to expand...
So, what you are saying is then, that although the design was intended to have the pin ride the lugs (instead or riding the link), only a custom fitted gun is likely to do that?
 
Then, the majority of factory pistols, being "link riders", are not functioning as designed, and the caming surface of the lower barrel lugs and the slide stop cross pin are not functioning correctly as intended by John Browning?
Click to expand...

dahermit,

I am not an expert and I am still on a steep learning curve. I have built several 1911's, and I learn more with each one. To answer the above quote, no. The link was never designed to facilitate vertical lock-up. It's function is to pull the barrel down during the recoil cycle. This is discussed in Kuhnhausens manuals, the Scheumann website, and can be further desiminated in the Gunsmith section of the 1911 forum using the search feature.
 
I probably need to start over. I see I was operating on the premise you were fitting a gun because you were talking about link fit. The tolerances are such that a standard link is all you need if you are not fitting the gun up in other ways. By itself, a longer link causes pin riding and drives the barrel both up further on closing and back further on opening, which can lead to the failure to drop down into the cradle in the frame completely, with the attendant interference and timing issues mentioned, so some fitting beyond the link itself may be required. But lengthening the link alone still allows some left-to-right and tilting to occur that prevents peak accuracy coming out of that single alteration.

As I described, once you get to barrel fitting and the rest, the link lugs, even on custom barrels with extra metal, have to accommodate the shortest link, meaning the pin cannot be pulled so closely into the link lugs on the barrel that it can't move freely. But that does not necessarily dictate riding the link. That only dictates clearance coming out of battery, as the barrel is driven back, which pulls against the link, creating maximum distance between the pins (link pin in the barrel link lugs, and slide stop pin in the frame).

Going into battery is another matter. If the holes in the link are big enough and the tolerance of the slide stop pin and all else is great enough, as is the case with a lot of old timers, the forward movement of the slide can still push the barrel forward into that tolerance freedom, pushing the two pins toward each other so the lower link lugs still ride the slide stop pin up. But the tolerances have to right.

Any gun with enough tolerance free play will let you feel it. Let the slide go into battery on the empty gun, then stick a dowel rod or even a pencil in the bore and, resting your thumb on top of the barrel at the ejection port while you pry down against the muzzle with the stick, you will feel the barrel slide further up into the engagement.

That all makes the gun work, but it is not tight enough for peak accuracy. That's all. Once you start messing with tighter parts and eliminating the free play, you have all the other i's to dot and t's to cross that I mentioned before. Changing the link alone does not a precision match gun make. The Dwyer Group Gripper is the way to take that approach if you want to try it. It helps some and does not introduce the problems with swinging the barrel too far to the rear.
 
What precipitated my post was:
Years ago, I purchase a new Colt .38 Super Combat Commander. After shooting the gun for awhile, I noticed that the locking lugs on top of the barrel were being deformed just behind the front locking surfaces. Having many guns, going back to college, divorcing, moving to Southern Michigan, after several years( it was a series 70). I decided to take it to a Gun Store with a gun smith and have the problem fixed.

The "gunsmith" told me that I needed a new slide, as that was the problem. they installed a new slide. After awhile, I decided that I should replace the damaged barrel also, which they did.

Being old, forgetful, and not shooting that gun much (I used it for a hidden, loaded, bedroom gun), I had forgotten that the new barrel was not damaged. But, the picture of the damaged lugs on the barrel were still vivid in my mind, and I though that I had better replace the barrel. I ordered a new barrel. It arrived, and I Begin to research timing of a 1911. Upon disassembly, I found that the barrel I had replaced by the "gunsmith", was NOT damaged. In short, I did not really need to replace the barrel again.

It would seem from what I have learned from these posts and from the 1911 site, is that it was likely a timing issue, not a "bad slide" issue.

Nevertheless, having researched 1911 timing, I found myself engrossed with the intricacies, and wanted to learn as much as I could.

So, that is why my posts may seem confusing, At first I anticipated replacing the barrel, but at later point, I just wanted to learn.
Thanks for the information.
 
To get a fit that is guaranteed to ride the slide stop pin all the way up into battery, you have to go to the old school method of weld build-up on the barrel link lugs and a hand-scraped fit that rounds the corner in contact with the pin.
Click to expand...

Or just start with a 'gunsmith fit' barrel that has the feet left oversize for cutting in the frame and slide.

Brownells even sells the lug cutter.

A little filing after cutting and you get a smooth curve and correct lugs.

I use the smaller all the tine and then finish up with a file.
 
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