fitting 1911 barrel

Briefly, what is the fitting sequence of a barrel in a 1911, in terms of the upper, lower lugs, hood adjustments and link components? So the pistol will hold 2 in. or less at 50 yds... also to consider headspace.

I assume 2 inches with a Ransome rest-easier to achieve than with sand bags or off hand. I once saw a video of Jim Clark Jr. fitting a 1911 .38 Special barrel and then testing in a Ransome rest in a tunnel. I do not know if they sell the video.

I have only fit one barrel that will do 2 inches at 50 yards. It is a Kart NM "EZ" fit. It comes with 12 pages of small print instructions and some fitting components. It took me 15+ hours to do it. None of the other pistols I have completed will do 2 inches at 50 yards so I am no expert. I have a Custom Open STI that will do 2 inches at 50 yards but I did not build it.

For that kind of accuracy I suggest you get information from some one who some experience building bullseye pistols reasonably frequently.

Also it takes a little time to learn how to use the Ransome rest and get repeatable results or at least it did me.

Whew! This one could get involved. There are several differnt views on the question of match-grade barrel fitting, and almost as many approaches.

The barrel is fitted in two planes... vertical and horizontal. In the horizontal, lockup is achieved with a tight fit between the front faces of the locking lugs to the corresponding rear faces of the lugs in the slide. This is achieved by using a long hood and adjusting it to fit into the slide with zero play so that the thrust faces are in contact with the pistol in battery.

Some smiths take the approach that only the first lug is necessary with a .45 ACP caliber pistol because of the low pressure. Others want all lugs bearing an equal part of the load. I like equal distribution over all three lugs if I can get it.

Then there's the vertical lockup... the amount of the total lug height that engages the slots in the slide... in an attempt to get as close to 100% engagement as possible. This is usually doable on the first lug, but not quite so on the two forward lugs due to the tilting barrel. More clearance for the slide is available at the rear because it falls lower than the front lug... so a compromise is necessary.

The other factor is the centering of the barrel in the breechface, so that the firing pin will hit as close to dead center as can be managed. Lug heights on the barrel to slot depths in the slide need adjustment. Some smiths don't place a great deal of importance on this factor.... but I do. I've been known to weld a lug and refit it to gain an extra .003 inch. Extreme... and probably not necessary... but sometimes I like to see just how close I can get it. No time constraints are a good thing.

Basically, I like to start with a "Hard-Fit" barrel with long hood and short chamber and go from there. By gauging the distances from the breechface to the thrust faces of the slide lugs... and the distance from the hood face to the thrust faces of the slide lugs... I can adjust the faces of the barrel lugs themselves to get equal lug contact... or leave a tiny gap between the thrust faces in order to let the lugs pressure equalize on firing. This requires cutting the chamber short and firing the gun to "Slap-Seat" the lugs. This gap must be very small...no more than about .001 or .002 inch... along with a fairly tight hood fit to allow the lugs to seat without losing the tight horizontal lockup provided by the hood. When they seat, the fit of the hood loosens up a bit due to the barrel shifting forward in the slide as the lugs set back to equalize. Then, the chamber is finish-reamed to depth. I like to set that depth at .003-inch to .005 inch over minumum as determined by using the SAAMI standard GO gauge. (.898 inch) My primary gauge is .895 inch.

At that point, the decision is made to either leave the hood with a zero- clearance linear fit in the slide, or file a couple of thousandths off to provide a little dirt clearance... as the intended role of the pistol dictates. Target pistols don't get the clearance. Carry pistols do.

Then, there's the vertical lockup provided by fitting the lower lug to cam the barrel up on the slidestop crosspin. You want zero vertical play at the rear of the barrel... but you don't want it to bind as it goes into battery. Again... a purely target pistol gets a little tighter fit than a carry gun, but there is very little difference here. I typically fit a carry gun as tight as a match gun and finish-lap by hand with a length of .200 drill rod.

The sides of the hood are also a consideration. Target guns are held close to zero clearance there. Carry guns get a bit more. Ordnance-spec, or production guns are pretty loose here...as much as .010 inch per side. A fitted hood on a carry gun can do pretty well with a lot less, and still allow for dirt and carbon fouling. For a carry gun, I like to see about .003 inch per side, but a little more is okay... up to about .005 inch. What you're after here is limiting the barrel's tendency to rotate...or torque...when the gun is fired. The fit of the sides of the lower barrel lug to the frame recess is also a limiting factor, but there has to be a little clearance there to allow the barrel to link down, so it can't be the limiting factor. The fit on the sides of the hood also aid in returning the barrel to the same position on every cycle.

The most important thing is that the barrel lock up well at the bushing... the hood... the bottom of the lower lug to slidestop pin, and equal support of the lower lug on the pin from side to side... and the barrel crown.

I think that too much is made of the slide to frame fit, side-to-side. It plays a role in the overall picture, but only a small one. You want to hold it pretty close, but zero isn't really necessary and is a detriment to free slide movement. More important is the vertical... or up and down clearance between slide and frame. I can live with .005 inch of side-play as long as I can get nearly zero in the vertical plane.

Back during the 1960's the Army experimented at Springfield Armory while they were building USGI National Match pistols for various military shooting teams, and for use during the National Trophy Match (pistol) that was held each year at Camp Perry, Ohio. These pistols were in relative terms, mass produced and all were built on USGI 1911-A1 frames. The first "hard fit" barrels were designed and made for the National Match Program. Before this gunsmiths had to weld up the hoods and lower barrel lug and then fit the barrel to a particular gun.

At the time, the program was run by an engineer named Gene Taylor, who had forgot more about the 1911 then I'll ever know. Fortunately he was very generous when it came to handing out information.

They're accuracy standard was 5 shots off of a machine rest at 50 yards, with the bullets going into a group no larger then 3-inches measured center-to- center between the two most outside shots in the group. They used National Match grade hardball ammunition, which was required in the matches where the pistols would be used. This 3-inch standard was about the best the ammunition would do out of a bolt action barreled test fixture at the same distance. BTW, they tested all of the guns they made, not a selected sample.

At one time they built a series of pistols, where after each step in the accurizing process the pistol(s) were machine rest tested to see what affect each step had on the pistol's ultimate accuracy. Slide-to-frame fit only accounted for 3 percent of the total improvement. By far the most important factor was barrel-to-slide fit.

Consistent groups at 50 yards of 2-inches and under are very difficult to get because of limitations in the ammunition as well as the pistol. If and when this is done the pistol must have absolutely zero tolerances in the barrel's lockup when the gun is in battery. This may be fine in a pure match pistol, but it isn't anything I'd want in a weapon. In this case "zero tolerance" is an invite to malfunctioning as soon as the pistol gets fouled or lubrication displaced.

Two-inch groups at 25 yards are relatively easy to get, and a more realistic standard for anything except a bullseye match pistol.

Weldin'em up and cuttin'em back to fit... Ahhh! Those were the days! Bad ol' days! Those "Hard-Fit" barrels are the nuts, and I understand... though I don't know... yet... that the Kart EZ-Fit system is the double-nuts for the hobbyist.

Part two:

Bushing to slide and barrel to bushing fit is one critical area that needs to be addressed a little further, lest the first-timer think that all he needs to do is make it good'n'tight. The barrel tilts... up into battery/lockup...and down into unlock/linkdown. If the bushing to barrel fit causes the barrel to be forcibly locked in the vertical plane, it creates "Barrel Spring" and actually bends the barrel in the middle. Not a good thing. The bushing needs to be clearanced a bit at the inside rear area... and sometimes a little at the front bottom... to allow the barrel to vertically lock in the slide without requiring force.

Then, there's the matter of linkdown clearance. Most production, ordnance- spec pistols come with barrels that have a slight flare toward the muzzle end. This allows for a closer fit with the bushing, and still provide adequate clearance behind the flare for the barrel to unlock. This flare is sometimes referred to as the "Fitting Pad." The diffrence in the two diameters typically runst to about .006 inch or so... and if your hard-fit barrel doesn't have it, you'll have to put it there, or go with a bushingless system. This is accomplished with a barrel turning fixture and a lathe. It's also helpful to scrape a little clearancing provision at the rear bottom edge of the bushing, just for a little added insurance that the barrel will fall into bed.

And THEN there's the little matter of adjusting the barrel stop surface and frame bridge so that the link won't be stressed and stretched by the barrel stopping on the bridge... and so that the barrel lugs won't be peened, rolled, or sheared by the slide if the barrel hits the stop surface before it's completely unlocked, AND THEN there's the matter of selecting the correct link to match the lower lug's dimensions and geometry... and it goes on and on.... don't it?

I had a smith install a BarSto and after taking it back twice, it is still loose and the gun won't shoot (large groups with my best hand loads), they had welded the hood and filed the lugs when they promised that they would use a lug cutter and didn't and the hood fit still rotates, so I propose to weld the hood and lower lugs and recut myself, but I must get all the operations in correct order, right?

My vision of my fitting of a barrel in my 1911s is in 3 planes/dimensions with spiral rifling and torque issues whether I hard fit or use a Kart NM "EZ" fit barrel.(I can do both). I am however only an amateur "hobbyist" not a professional gunsmith/pistolsmith/armorer. Are only 2 planes important for 2 inches at 50 yards?

Go back and read it again. I touched on the torque question in the part about hood width/side play in the slide's recess. I don't think of rotation due to torque as a plane. but rather a directional response to torque. (Length/Width/Depth... or XYZ axes.) Vertical... Horizontal... Side play

The third plane is fore and aft, ain't it?

Enquiring Minds Want To Know!

Nah... That's included in the horizontal lockup. Barrel lug and hood face fit, etc.

The adjustments and fitting are for a bullseye match pistol, and as far as the barrel fit is concerned, the hood fit is touching the breech at the corners, the lower lugs lightly touch the slide pin, the bushing has almost zero play and is clearanced to allow unlocking and locking, the only area that i suspect is the upper lugs. I can slide a cig paper (.001) out of the top lug without tearing. Now, if that's the case, the hood touches the breech, the lower lugs are a good fit, the bushing is tight, but the upper lugs are suspect. Is this not good? what should be the case and what should be done to make it right?

If that Bar-Sto barrel has been welded, and especially if it has been welded more then once, I wouldn't continue to use it. It sounds to me like this sorry example of a gunsmith(?) doesn't know what he's doing, and by now the hood and lug areas may be embrittled or excessively soft. Rather then take a chance I would purchase another barrel and have Bar-Sto fit it. They know what they're doing and they don't do it by welding.

Little confused here... If the clearance is between the top of the hood and the frame bridge... that's not the lug. The thrust face of the first slide lug is under and slightly forward of the bridge, and the thrust face of the first barrel lug is at the front of the hood.

If there's clearance between the first thrust surfaces, the #1 lug isn't bearing any of the load and is being held off by one or both of the two forward lugs. If this distance is very tiny... maybe .001 inch... the lugs may equalize in time, after firing it enough.

In agreement with Fuff, by the way. Unless the welder knew his stuff as to quenching and drawing the steel back, you could have some metallurgical problems within the welded areas or slightly beyond.

Agreed, there may be issues with the welding of the hood, and I will find out what kind of welds were done and deal with those problems later. Although if it were just welded and cooled then the steel is then in an annealed state and will be subject to premature wear.

The danger of course if it were heated to correct temp and quenched to harden and not drawn back will likely cause fracture and breakage. My concerns are with the upper lug fit with the slide. If I can slide a feeler through the first lug, what does that mean in terms of lockup at the moment of firing and when the slide moves back the short journey before the bullet leaves the barrel?

As the slide/ barrel move rearward, the lugs still contact the slide stop pin say at least .080 so that means the upper lugs are still in contact, further meaning that correct alignment is still established... but where is the upper lockup then? It must be in the hood/breech contact that is holding the upper lock? right? Nada?

If not, how can I check to find out what lug surfaces are contacting (I guess I can use layout dye) but more important, just exactly what surfaces are supposed to contact and where. I think we are getting close to problem.

Let me throw a few numbers out and see what we can glean from that... I think the answer is in the unlock/linkdown timing of your pistol.

When the pistol fires, slide movement begins as soon as the bullet moves, though it's more sluggish due to the greater mass. The barrel and slide move together for a short distance, and unlocking begins. That distance varies from gun to gun, but it occurs at roughly .090 to .110 inch of travel... and the barrel STARTS to unlock. This is for ordnance-spec, or production guns.

To further enhance accuracy, when a smith sets up a match-type gun, he tries to keep the barrel locked to the slide for as long as possible... but there's a limit to how much it can be delayed... About .125 inch of slide movement, but it can vary a little from gun to gun as well, depending on how everything stacked up when the pistol went together. Lower lug geometry and length of the link have the final say in exactly when the unlocking phase begins. Generally speaking, the longer the barrel remains locked into the slide, the better for accuracy. This will also serve to partly explain why we encounter different accuracy levels in identical factory pistols... and varying points of impact too.

If your gun is starting to unlock early... at .080 inch of slide travel... that could be a big part of the reason for your accuracy issues. I've seen some factory pistols begin the unlocking phase so early that the shooter was getting hot gasses blown into his face from the breech.

Unlocking begins, and the barrel starts to tilt. At about .250 inch of slide travel, the barrel is fully unlocked and down... or it should be... and there should be clearance between the top of the barrel hood and the underside of the slide's first lug... the one just under and forward of the bridge. Some say that .005 inch is minimum, but I like to see .012-.015 inch or more. This clearance is necessary to keep the slide from knocking the top front corners of the locking lugs off.

Mine starts to unlock at .080 and I thought it would be enough to keep it locked before the bullet left considering I use lead 200 grain bullet and I also use a full Bomar rib making the slide/barrel rib heavier than normal which slows down the mass somewhat.... the slide is fit on the frame enough that the safety is just able to lock and then a little, the slide /frame fit is about flush but if I cut the lugs say just another .030 I would be in the .110 range (better i think) but what problems would I encounter if I did this?

And to complicate matters even more -

When the barrel is designed and fitted to be cammed into its final position by the slide stop pin and lower lug pressure, the link has an oversized hole for the slide stop. Thereafter its only function is to pull the barrel downward to unlock it as the slide moves backwards. But depending on the size of the hole, and the distance between the holes in the link, the timing can be changed too.

Da' Fuff will now suggest in his usual blunt and undiplomatic way, that if maximum bullseye match accuracy is what you want, you’re going in the wrong direction. Given what your present barrel has gone through I think it’s unlikely you will ultimately get the kind of performance you are looking for. If this pistol was an ordinary toy I'd say, "have at it," but apparently this isn't the case. Having been an active bullseye shooter at one time, and good enough at it to be a member of a State Team at Camp Perry for several years I know of what I speak. What you need to do is:

1. Dump the mis-named "gunsmith" that butchered and ruined your Bar-Sto barrel.

2. Get a new barrel and have it installed by a real professional. Clark's come to mind, and if I went to them I'd go by they're recommendation on what kind or brand of barrel to use. Or if you choose to use a Bar-Sto go to them. Most of the top 'smiths will return your pistol with a 50 yard/machine rest test target. Expensive? You bet! But do-it-yourself experimenting on match- grade barrels isn't exactly cheap.

3. By all means, practice fitting a barrel (starting with the one you now have if you want) but go through the learning curve without starting on your best match pistol. Again, speaking from experience, you won't likely get 2"/50 yard groups on the first attempt no matter how you do it.

You might try cutting the lower lug a little farther back. I don't know if I'd take it as far as .110 inch though... I like to try to keep'em about .112- .115 but if your gun isn't heavily sprung, it may be okay. That would keep the barrel locked a bit longer. The amount of difference that it would make depends a lot on how well everything else is fitted... and it would set the slide further forward on the frame quite a bit.

Fuff touched on another point that needs consideration. The link and the timing of the whole shebang. If the rear radius of the lug is cut farther back, the link will pivot farther past dead vertical than it is now. If the link's position is now correctly about one-half degree past vertical... you may run into a little problem there if the clearance between the slidestop pin and the hole in the link isn't sufficient to prevent stretching the link. If the link gets stretched, it delays the linkdown timing of the barrel... and that could bring on problems with unlock and linkdown timing of the lug- bustin' kind.

Might be best to take Fuff's advice. Ditch the smith and find one who knows how to correctly fit the barrel for match guns. These things have to be in the right order. Sorta like an algebra problem. Once you go wrong, it's wrong from that point forward.

Practice fitting my own barrel (yes), go through the learning curve (yes) I only need one 45 (wad gun) there are hundreds of gunsmiths that can accurize a milspec gun to shoot 2 in., I just have to find out how and jump through the hoops, I don't mind.

I took it to another smith after the range yesterday and he checked centering of the barrel with Brownells centering tool and could not fault the centering, he said the rear hood/breach fit was a kiss fit in length and decided that it was not excessively tight and the side clearances were not excessive considering the barrel is centered. He said the slide/frame fit was almost perfect, could not detect any vertical or horizontal movement (showed me three STI pistols that all had a lot of felt movement) the bushing has no movement in lockup.

He did slide the slide back several times to feel when the lockdown started and wonder if he felt that is was marginal, but didn't say anything. the lower lug fit was sufficiently tight enough not to be an issue in his opinion. Headspace is within spec. He checked the link and noted that it was likely a .288 link and felt that it was marginally tight when it gets to vertical during lockdown movement. He felt the pistol would be as good as he sends out his door but, I think that .080 is not enough to keep in lockup, but hey, what do I know.

So, you are starting to look elsewhere and my ammo is very carefully assembled with hard cast well filled out # 68 wadcutter 200 grain weighing 197 grain with lino added to the mix. Tried 231 and Bullseye with taper crimp to .468 and 4.1 Bullseye giving the best group. Of course I have tried varied crimps powder amounts etc. I'm kinda like a doggy with a bone here and I think that i'm almost there, seems that something simple is the culprit.

I highly doubt that your ammunition is at fault, but just for grins you might try something else, and/or try the ammunition in someone else's pistol.

If you can, fire several bullets into a soft medium and then recover them. Use a good glass and look at the rifling marks to see if they are tapered and wider at the base. Forty-five pistol barrels have shallow rifling, and sometimes softer lead bullets will skid because of the torque. When this happened I could detect a difference in accuracy at 50 yards, but not at 25.

Bar-Sto barrels usually fit fine, and in my experience offer high accuracy. However, seeing what this particular one has gone through I wouldn't make any bets. It isn't the obvious things that are hard to correct, it's the others that require experience to detect.

Last but not least, test the pistol at 50 yards using a Ransom or similar machine rest. This is the only way to find out what the pistol & ammunition(and not the pistol/shooter combination) will truly do.

Actually, I had some metal that tested BH 23 and cast couple dozen bullets and carefully measured dia. and weights at 192 gr, picked ten best, bullets were perfectly filled with with sharp bases, sized with Alox/beeswax with the base rod center machined out to give a shoulder to seat on without interferance with the cutoff sprue, my seating die punch is also machine out so that the bullet is seated on the shoulder of the wadcutter for almost perfect alignment seating the bullet and l have seated bullet out enough about 1/30 in to give me a base/shoulder length about .906. These 10 rounds simply made a slightly smaller group. I was disappointed with this result as I expected a huge improvement, but just wasn't there.

So, ok, gurus, dig deep, there is something in the gun that isn't kosher... this gun, ammo combo should shoot one hole at 25 yds all day long.

Tuner, you said that you don't know if you would go to .110, but you also stated that you like to keep it aroung .112 to .115, ... I dont get what you mean, so considering that I have only .080 , is that dicey? What would you take it to? Give me a figure that you would do if it were yours and I'll try it and go from there, no obligation here, if it does't work I'll have it rewelded and do it over again

Hmmm, no more answers, must be getting everyone down. OK, so I have done a test on the lockup. I put the pistol in my machinist vise without the spring or the link and fit a dial indicator on the slide and also another vertical indicator on the hood of the slide (vert ind. reads tenths) keeping thumb pressure on the exposed barrel while moving the slide back.

 .020 rear slide back ---.0015 barrel down
 .045 -------------------.0005
 .070 -------------------.001
 .080 -------------------.0025
 .085 -------------------.003
 .090 -------------------.004
 .095 -------------------.005
 .100 -------------------.006
 .110 -------------------.0085
 .112 -------------------.0095
 .115 -------------------.010
 .130 -------------------.015

So waddya think?

I know, either a new barrel or weld the lugs.

So I guess the next question is what welding technique should I use, MIG ok?

Your barrel is droppin' pretty early in the cycle, but a lot of that may be due to the thumb pressure. Since the barrel would be held forward during live- fire, repeat the test by just letting it fall on its own, and use the link this time.

From the sounds of your first test, your lower lug seems to slope a little too sharply, since the barrel is falling at a pretty constant rate through the slide travel. You may be able to keep it locked a bit longer by making it a little straighter without giving up a lot of vertical lock. It wouldn't take much to keep the barrel locked to the slide to the .050 inch mark, which would just about cut your error in half. Might work... Might not... depending on how much vertical lock you lost when you flatten out the slope. It's worth a try, since you're either gonna weld the lug or rebarrel it.

Don't know a lot about welding stainless, I'm afraid. So many different grades of SS, and you'll just about have to know exactly what you've got to make an accurate call on how... and what method to use. Maybe somebody that knows will chime in.

One little trick that has seemed to enhance accuracy while working on pistols in which accuracy enhancement wasn't the object of the exercise... is the fitting of a small-radius firing pin stop to the gun. It doesn't keep the barrel locked to the slide longer, but it does delay the slide for a split nanosecond... which pretty much accomplishes the same thing. The results varied from gun to gun... but most of the reports indicate that there was some difference. That might also be an option, since accuracy comes from several little things working together toward one end.

OK I'll test again with the link installed.

Looking at the first test, it pretty much stayed in lock until .070 which seems a little short, right? And I was hoping you might say to cut the lug another .010 and try it, and maybe another .010 later until it corrects. I don't know the formula for calculating just how much rearward slide movement is critical, what seems to be the average?

Cutting more metal off of the lug will likely cause the unlocking to be sooner, not later. You need more metal where it isn't.

I know the firing pin stop trick can be useful with hardball, but I'm not sure how it would do with lighter mid-range target loads. In general, target 'smiths try to make unlocking easier with softball guns, especially those with Bomar ribs. Tuner?

You can expect slide advace on the frame about a 3:1 ratio if you cut the lug further back. Not sure of the exact formula for calculating it, but that's about the amount I've noticed in some few that I've adjusted the lug to delay unlock... none of which were for accuracy, but to stop tadpole-tails on the primers and gas in the face.

Your barrel drops .001 inch at .070 inch of travel... without the link. Adding the link to the mix may give a different result, just like not using pressure on the hood. Also... don't forget that when the barrel is under pressure, it's not gonna drop from the slide under gravity alone. It has to back off the pin far enough that the link can exert its influence without the lug solidly on top of the pin. The more slope on the lug... the earlier... and the more... it drops.

All this may be for naught, though. Looks like you may wind up with another barrel anyway if you can't get the gun to shoot like you want by massaging this barrel.

True enough... but reducing the amount of slope on the lower lug would limit the barrel movement past the point of starting to unlock, and maybe serve to make it a little more stable. Like I said... Might work and might not.

Worth a try, since he's pretty much figgerin' on barrel work anyway.

The firing pin stop's influence can be offset softball with a 2-pound drop in recoil spring load if need be... but it may not. I've got a pair of early 1991A1s that have a 23-pound mainspring... a 16-pound recoil spring... and the small-radiused stop. Just for the helluvit, I shot some of Kelie's Softball ammo in'em... 185-grain lead bullets loaded to 700 fps...and the guns cycled well enough to lock the slides 7 times in 10. I could clip one coil off the recoil springs and they'd run, even though the brass falls on my right foot.

At times i can be a real dumb bunny (maybe Easter has something to do with it), but i do not understand Old Fuff stating that not cutting more is better?

Ok,the first barrel they put in wasn't cut enough, the slide was not even with the frame by at least .040 , so when the slide comes back the .080 or so in recoil the slide was already back by .040 and it only had to come back another.040 when it started to unlock... all my cases were black, because the slide/barrel was unlocking while the pressure was way up at the beginning of the internal ballistic...

Having said that with this 2nd barrel that was installed the cut on the lugs is likely approximate in the positioning but only marginally so... because the barrel is really starting to unlock about .070 an isn't that early? If I extended the cut another .010 or even .030 more, wouldn't I get into the better zone where the slide is still in lock before the bullet exits the barrel? Where and what am I missing if that's not correct?

I believe he has a slide with a heavy Bomar rib. In that case the slide will almost run on momentum alone. They were designed and intended to work with very mild pussycat loads. I am sure the extra-heavy slide will have some effect on the cycling rate. It should be slower to start, but then it will go like gangbusters if the recoil spring is too light for the cartridge's load.

Mike:

It depends on where you're removing metal. If it is on the bottom lug in front of the slide stop pin the barrel will drop down sooner as the link pivots the barrel downward and backwards. That is, if the link will let it do so.

Another thought has come to me. If you have a set of twist drills find one that will just go through the slide stop hole in the link and then mike the diameter. Could be that the link is part of the problem.

I see... I see... Okay! Nix the lighter recoil spring then. The FP stop still might be workable, though.

Same ol' same... Change one thing, and ya might as well get ready to change 3 or 4.

Fuff, Mike was thinkin' about a cut on the lug that would set the pin deeper.

I suggested makin' the bottom part of the lug flatter to keep the barrel closer to the same place longer in hopes that it might limit the arc as it drops... even though it would still start a little early, it would remain at THAT point over a longer time frame. Might help... Might not.

Darn, on to test #2 with link installed, I believe it is .010 longer than standard.

I make mistake on setting up the up/down indicator, so here goes again.

The indicator stays at zero untils there is .110 of slide movement where it drops only .0005, then at .115 it practically drops like a rock almost immediately... looks like the barrel is riding the link, right, No? Not good huh?

I made a pin that just barely fits the slide lock pin hole a very tight fit, measures .201, the slide lock pin that I use now measures .1995, I used this pin for the test and for what it's worth, I just replaced the recoil spring with a new Wolff 14#

The light is starting to dawn...

Put some layout dye on the bottom of the lug, reassemble the pistol, hand cycle it, and then look at the bottom of the lug to see if the slide stop pin is rubbing, and where.

If the link is long, and the hole isn't oversized, it is probable the link, and not the lug is what's locking the barrel as the slide goes into battery. You should have one or the other, but not both together.

My USGI blueprint for a link modified to be used when the barrel is cammed by the slide stop pin has the hole dimensioned at .230 +/- .001 center-to-center dimension between the holes at .291 +/- .001

Are you saying the hole in the frame, or the hole in the link is .201"?

Light at the end of the Tunnel!

Yep... sounds like you might have a "rider". A quick-check is to just look at the slidestop pin to see where the the rub mark is. If it's the same width as the link... and on the top of the pin... it's a-ridin' it.

To verify... ease the slide into battery and measure the distance from the top of the slide to the top of the hood with and without the link. If it locks higher with the link... it's a-ridin' it.

Tuner, that's exactly what I thought on the last test, that the barrel is riding the link and not the pin.

Old Fuff,

with the pistol assembled including link, I can just barely fit a .201 pin where the slide lock pin fits... I'll try the dye test later. What part and why is it not good for the barrel to ride the link? Like, what happens?

Applied layout dye on the barrel lugs and the slide lock pin. After cycling the slide several times, there are two bright spots on the top of the pin that interfaces with the lugs , there are bright spots along the contact area on the lugs where the pin slides along full length as well. There are not rub marks on the pin where the link would interface.

I measured the slide lockup height with the link installed and removed, the measurements were identical

This is going to take some thought... and by now Tuner has gone to bed.

Be that as it may. When a barrel is cammed into battery by the slide stop pin pressing on the lower barrel lug the link is supposed to have an oversized hole in it, and thereafter only drops the barrel to unlock it and nothing else. I would expect the link in your barrel to have a .230" hole for the slide stop pin, which is about .200 Since the pin is acting to cam the barrel the hole location and size in the frame and link, and the diameter of the slidestop pin must be held to the closest possible tolerances. The hole in the link can be, and should be about .030 oversized. It would appear that in your case it isn't. But maybe the cam surface in the lug is so close it doesn't mtter because there is enough tolerance stack to allow the barrel to ride on the slide stop pin, and the tight link doesn't matter. If so, this is a first for me.

If the pistol was laying on my workbench, or on Tuners, we could make some solid judgments in short order. As it is we have to give out a lot of speculation.

Another test. Insert the slide stop through the link and frame, and then lower the slide into batttery while the slide stop lever is pointed down rather then in place. See if you can pivot the slide stop. If the barrel lug is pressing on the slide stop pin there should be resistance. If there is, see how far you have to push the slide/barrel backwards before the pressure on the slide stop pin goes away, or if it does at all. What I'm looking for is evidence of binding.

Now it's past my bedtime so I'll have to get back to you tomorrow,

Old Fuff... here's a good morning question for you, with the pistol assembled and the slide stop pin hanging, do you mean to push down on the barrel while closing the slide to lockup? Should the recoil spring be in? I guess I may not fully understand the test, can you try explaining again?

What am I doing? Not sure, but at this point Tuner and I are playing hunches. It would seem that your barrel is being locked into battery by both the link and the camming action of the lower barrel lug bearing on the slide stop pin. If so this shouldn't be, and in fact something should be binding, although so far I don't see evidence of that.

So long as the pistol can be pushed into battery you don't need the recoil spring, but of course you do need the barrel bushing. You also don't need to push down on the barrel at the hood, because it seems that either the lug/slide stop pin or link (or both) are pushing the barrel upwards into a firm lock-up. If the link is removed you probably will have to push the barrel down to get it to unlock at the start of the cycle. What I am looking for is if the slide stop won't pivot if when the barrel is in battery - indicating that pressure from either the lug or the link is causing a bind. I would expect that if the barrel was cammed into battery by the lug/slide stop, and that could be determined by removing the link and repeating the test to see if there was more or less pressure on the slide stop pin. If the barrel is standing on the link I would expect it would take some pressure to push the slide into battery, and a slide stop that didn't want to rotate - unless the link fit was absolutely perfect.

An old pistolsmith's trick is to assemble everything (and/or with or without the link) and hand-cycle the slide without the recoil spring in place. This way you can literally feel what is happening as the slide moves back and forth and the barrel unlocks and locks. Of course if the link has been removed you may have to press down on the hood with your finger or thumb to get it started in the unlocking phase as the slide starts back.

I think Tuner is looking at two things. First, the way the slide starts to move back while the barrel starts to unlock, and then suddenly "drops like a rock." This was something that was unexpected. The second thing is that the hole in the link is a close sliding fit on the slide stop pin, where we would expect a hole to be about .030" larger then the pin. This clearance is to insure that the link does not interfere with the slide stop/barrel lug's camming action.

As I said before, if the pistol was laying on one of our workbenches we would hopefully conclude something before long. As it is we have to speculate.

If you have not already done so, you should purchase a copy of Jerry Kuhnhausen's excellent little book, "The Colt .45 Automatic - A Shop Manual (Books 1 & 2)" - both books are in one volume, and Book 2 details how to hand fit a match barrel.

Back to the vise, link out, pin in... at lock, pin is tight, back the slide out .020, pin is very loose and the barrel is already dropping 2 - 3 thou. The numbers here are not the same as my first test, but there must have been some crud holding it up, but now it definitely drops very fast as the slide is moved back without the link.

Link in, pin is tight, move slide back, pin will actually start to rotate and will stay tite until about .090 then gets loose and another few thou. back the barrel drops fast, but stays almost zero until then. Almost identical to test 2

This slide has been lowered a lot to get a tight fit, I'm sure this has an effect on the link geometry, just my thought... another thought (dangerous) is in the link pin hole in the link, isn't this hole supposed to be pin size? Enlarging the hole at the outer will have an adverse affect on the timing?

Do you mean it should be .203 or .230?

In a regular 1911 pistol both holes in the link should be a slip fit on the respective pins that go through those holes. This is because the link both lowers the barrel when the slide is retracted, and pushes it up into the locked position when the slide is in battery. This usually leaves the barrel floating a little bit when the slide is in battery, but it is acceptable, and even desirable in a service pistol - which the 1911 was originally intended to be.

Bullseye target shooters however don't want any float, they was the barrel locked firmly with no movement to they'll get maximum accuracy.

During the late 1950's some custom 'smiths and armorers at Springfield Armory discovered that if enough material was on the barrel's lower lug, or the lug was built up with welding, it could be "adjusted" so that the lug pressing on the slide stop pin would cam the barrel into the locked position, and unlike the link would allow each barrel to be individually fitted to a particular pistol in a manner (if done right) would lock the barrel into a position where there was no possibility of movement each time the slide returred to battery. Of course fitting the hood and barrel/bushing fit played a part, but we can ignore that for the moment. However if the barrel was set up so that the slide stop/barrel lug camming system was used it was necessary to enlarge the hole in the link so that the link would only pull the barrel down to unlock and otherwise have no function.

When the camming system is used (as it usually is a all match target guns) the only modification to the link is to open the lower (slide stop pin) hole from .2045 +.001 to .230 +.001 In both cases the upper (link pin) hole remains at .1565 +001

The slide stop pin diameter should be .2003 - .2005 The slide stop hole in the frame should be .201 - .203 Hopefully it will be on the low side, but this is not necessary.

It appears that the link in your barrel is designed to both lock and unlock the barrel, and this is not what you are supposed to have. If the link is the one that came with the barrel it might be a good idea to call Bar-Sto and ask. Maybe your barrel wasn't intended to be fitted using the slide stop/barrel lug camming method. If it was you have the wrong kind of link.

Repeated the first test with a little help with my thumb on the barrel.

Link was left out. By .070 the barrel. dropped .001, at .085 it's .002, at .095 its .004, at .100 it's .005 and drops pretty fast from there.

The smith had likely used a std. fit barrel, I can see weld pits in the lug and hood area, then they bead blasted to change the welded appearance. The link is longer than the original by .010 by comparison . I tried a shorter one and it wouldn't fit around the cam on the lug, so this one fits perfect to get around the cam, and to continue if this pistol is riding the link, then it too long right, but a shorter one won't fit... so, my peanut brain says the only thing to do is keep the same link, but have the lug lowered a few thousandths by weld and recut the lug lower to free up the link? Is that the solution? Or, do what Giles did on his pistols, he soldered a shim in the lug recess on the slide, probably to center the FP and to get a favourable lug/link geometry?

Gonna do a little ramblin, the Browning design as described by Fuff and Tuner point out that the barrel locks and unlocks by link alone. OK, to make it accurate you must get rid of the link arc and so smiths lower the lug and put in a shelf for the link pin to ride on within full lockup the entire way. Again as Fuff says, the link is loose and the only function it serves is to pull the barrel out of lockup. Again ,OK, in my case it seems the link is long by likely a few thousandths, so why not cut the inside of the link hole a thousandths at a time until the lug is clearly running the shelf. Then tests with link in and link out should be identical... but somewhere I am led to understand that doing this is undesirable, and I don't know why... it seems the present link is ok for timeing and pulling the barrel out of lock, so I don't see any gain to change that. Somthing else that I just remembered, the slide was tightened/squeezed quite a bit and you can see where the barrel has been rubbing the full length of the slide