View Full Version : 1911 barrel clearance
June 4, 2011, 11:23 PM
Iv'e got a used PT 1911 and am interested in tightening the barrel/slide combo.The bushing has aproox .005-.006 clearance inside and outside so there is about .010 to .012 that the barrel can move when locked and ready to fire. How much is "normal" clearance and is this a good spot to gain accuracy. The gun shoots fine, no problems, just kind of inconsistant with grouping. (lots of fliers that my other 45 doesn't have with the same ammo).Iv'e even been clamping it in a vice to eliminate me as much as possible. I don't know if sending it to Taurus will be the answer since it doesn't technicaly have a "malfunction" Otherwise the gun is in great condition looks to be fairly "new".
June 5, 2011, 12:25 PM
You can try, but I honestly doubt that you will get any satisfaction from Taurus as it is probably within their specs. Plus folks with lots more serious and obvious problems have reported poor results from Taurus customer service.
There are several potential causes for inaccuracy in a 1911 type pistol and the barrel/bushing fit is only one. One way to tackle that problem is to buy an undersize bushing and fit it to the barrel and slide. It is a fair amount of work and requires patience but the results are often worth it. Further it is a DIY job that a gunsmith will charge a lot of money for. (Make sure there is clearance for the tilting barrel, though.)
Then there is the barrel itself. Again, a custom barrel that can be fitted is a good (though not cheap) solution. Then add trigger pull, the shooter and the ammo to the mix and it becomes clear why there is no simple answer to accuracy problems.
BTW, using a vice is not a good idea for accuracy testing; to properly test for accuracy, the gun and rest must be allowed to recoil.
June 5, 2011, 02:54 PM
I think a well-fit barrel bushing has about .001" clearance.
If you can get accurate measurements of the inside diameter of your slide mouth and the outside diameter of your barrel at the muzzle, EGW (Evolution Gun Works) in Pennsylvania can make you up a bushing that's custom-fitted for your pistol. When you go that tight, ask for the "angle bored" bushing to ensure that you get proper barrel link-down without "springing."
June 5, 2011, 06:04 PM
I didn't like the idea of clamping the pistol down myself , I wanted to make every effort I could to elliminate me because I know the human is usually the majority of the problem in this area.The vice is a portable rifle vice so it did move when the gun went off so it wasn't locked in solid.
I was looking at those undersize bushings, Briley has a list of different sizes to pick one out that is .001 over the barrel dia. and they have a spherical brass insert,I think that takes care of the tilting barrel.The outside is considered oversize, but if my slide is on the big side it may fitas is, if not I'll have to take it to work and turn the O.D. down to fit my slide.
The trigger is pretty good as is.It ig tight and breaks clean and crisp at maybe 4lbs. It wouldn't hurt if it was 1.5lb lighter in my opinion,I'm used to 3/4 to 1lb triggers on my benchrest rifles, so careful trigger finger control is habitual to me.
June 5, 2011, 07:35 PM
Guru1911 here to help with your original question regarding barrel, bushing, & slide tolerances.
The measurement of the slide id, the bushing od, & the barrel od are added together. This is referred to as "total tolerance stack-up". It will give you the potential machine rest 100 yard accuracy if the ammo is up to the task. If your measurements are correct, the total stack-up is .018"---this means that @ 100 yards, the best group would be about 18" in diameter. 50% of the barrel lock up stability is at the bushing end of the slide !!!!!
Stay away from those bushings that have the pivoting inner ring !!!
A properly fitted bushing should yield about .001" clearance in the slide. You should barely be able to turn it with your fingers, but really easy with a plastic wrench. CLEARANCE BETWEEN THE BARREL & THE BUSHING SHOULD BE ABOUT .002"---JUST ENOUGH TO ALLOW PROPER BARREL TILT WITH NO "SPRING" FEEL WHEN DEPRESSING THE BARREL INTO THE SLIDE.
If you have any doubts about your ability to properly fit a "match grade bushing" to the slide & the barrel, let someone who knows what they are doing & pay them.
Any additional questions, please contact me by "pm"
June 5, 2011, 07:55 PM
Being an old timer, I am used to buying the undersize bushing and fitting it to the barrel and slide, rather than having bushings in every conceivable size already made up. Ah, progress!
Anyway, that is only one of the possible causes of inaccuracy. Another one is the failure of the barrel foot to fit properly on the slide stop. If that is not correct, or if the barrel is riding the link, accuracy will be erratic no matter how tight the bushing is. The front end of the barrel may be stable, but if the back end wiggles all over the place, accuracy will not be good.
The much discussed slide to frame fit (which has resulted in many broken slides as folks tried to pinch them to get a tight fit) is actually the least of the many problems.
June 5, 2011, 08:50 PM
I get .01 to.012 total clearance, the grouping is that bad . I can get 3-4in @25 with several reloads,however there are all those fliers that can be 6in away from the group, when my XDM can regularally get 2-3inch and no fliers with a trigger that is harder. I may try the bushing and go from there. Maybe eventually it'll turn into a "custom project" I did get the gun for$300 so it is definately worth it.
The slide to frame fit is on the loose side too, so ya, the back af the barrel can move around too.So it may not be worth it to put much into it.Someday trade it in for another 1911 (I like the "feel"of the 1911 a little better than the others)SR1911??
June 5, 2011, 10:20 PM
Jim & i are both from the "old school"---we purchase a brand of nm oversize bushing that we have learned to trust & keep several in stock. After measuring the id of the slide, we then turn down the od of the bushing to a close fit & then lap it in for the final.
We measure the od of the barrel & then ream the id of the bushing to a close fit & then lap and hand polish for the final.
With a properly fitted nm barrel bushing & a cut and polish on the barrel muzzle, the difference in group sizes will amaze you---if you can shoot well.
The whole point is to eliminate or minimize those mechanical & ammunition related problems with the pistol. Then if the shot is good or bad, the fault will lie entirely with you.
"the only nut i cannot tighten, is the one holding the pistol"
myself, jim, & scorch are here to help you & the other shooters on this forum with equipment related problems. Once that has been done, then the rest is up to you---practice dry fire, practice live fire, clean weapon, & repeat as frequently as possible.
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