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View Full Version : Questions on 1911 barrel fitting (bushing and link)


mikikanazawa
February 15, 2005, 02:16 AM
I've been reading as many 1911 'smithing books as I can get my hands on (Los Angeles Public Library = two thumbs up). ALL of them say to ream an undersized ID bushing to fit the barrel and/or turn down the OD of the barrel. Is there a reason why the barrel bushing could not be bored on a lathe to get the desired ID? I see that EGW has an "Angle Bored" bushing and figured that it could not be lathe bored AND preserve the angle, but I don't see how a plain ol' expanding reamer could do this either.

I have a lathe and am quite handy with it. I'd like to try fitting a bushing to "my" tolerances (learning experience) but don't want to screw up $100 in bushings in the process.

Second question, what is the standard procedure for checking the link length? I understand why you'd want to do this, but the actual checking eludes me. Is this a cut-and-try approach? I've seen the links at Brownells as small as .003-inch increments.

Last thing... I'm open to people's comments on the brand of small parts they prefer, specifically barrel bushings, slide stops, firing pins and firing pin stops.

BillCA
February 15, 2005, 10:41 AM
If you're interested in gunsmithing on the 1911, get the book The Colt .45 Automatic - A shop manual by Jerry Kuhnhausen. It's an excellent source of information. It's now in 2 volumes, but Vol 1 is the basic book and worth the $25 to $30 price.

As to barrel bushings...
If you think about it, in the operation of the 1911 the barrel has to move rearward and down as the slide operates. A bushing should be selected that just fits over the barrel's OD. Once selected, the bushing must be relieved in the right places to allow the barrel to "tip" as it moves rearward.

Usually this involves removing small amounts of bushing material at the lower rear of the bushing and top front. Think about the barrel having to "link down" at the rear, which causes a slight upward angle at the muzzle. Removing a little material in the bushing allows this movement to occur freely and not impair the movement of the barrel or slide.

Kuhnhausen devotes a couple of pages to proper fitting of a barrel bushing, complete with photos.

The reason you don't lathe or ream the bushing is that the rest of the bushing should fit snugly, especially at lock up before firing.

RickB
February 15, 2005, 01:28 PM
If you turn the outside of your barrel to match the ID of the angle bore bushing, you should have to do no other fitting. BillCA - on a standard bushing, material is removed at the lower-front and top-rear, to allow the barrel to tip UP; it's concentric with the bushing when it's unlocked. The beauty of the angle bore bushing, is that the critical lock-up fit is established in the boring - it's bored at the lock-up angle. You may have to relieve the barrel slightly, by reducing the diameter just behind the lock-up area by a few thousandths, but this could be easily done on your lathe. The drop-in angle bore bushing has a nominal .580" inside diameter, so if the last half-inch of the barrel was .479", and the rear part of the barrel was turned down to .474", you'd have a great fit.
Links of non-standard length are used when fitting an oversize barrel; you shouldn't have to fiddle with the link in a factory gun. A too-short link can result in insufficient slide/barrel lug engagement or the barrel "stopping on the link" in recoil, resulting in broken links. A too-long link can cause timing problems in link-down, resulting in damaged lugs on the slide and/or barrel, or preventing the barrel from seating properly in the frame when linked-down.
I also highly recommend the Kuhnhausen manuals (both volumes).

Walter
February 15, 2005, 11:30 PM
I recently bought an Ed Brown drop-in barrel bushing for my Colt Mk IV
Series 70 Gov. Model, to replace the "collet" bushing that came on the
gun. I mic'd my barrel and bushing, inside and out, before i ordered the
replacement bushing. It all measured within .001 of specs, on the "go"
side.

The bushing fit my barrel perfectly. The only problem I had was a "ridge"
on the exterior of the inside end of the bushing, making it a tight fit into
the slide. A few minutes with a fine file and a little 'medium' scotch-
brite, and it was all good.

Fifty rounds through the gun at the range the next weekend satisfied me
that the fit was good. I do think the old gun shot a little straighter that
day than it used to. But then, my pickup always runs better after I
wash it. :D

Walter

BillCA
February 16, 2005, 10:13 AM
RickB,

Seems that I wrote my article from faulty memory...
The bushing needs to be relieved at both the front top & bottom just enough to permit the barrel movement. The top-rear relief is cut if the barrel, in the locked position (off the frame) exhibits any spring that pushes the rear of the barrel down. (pages 44-46).

mete
February 16, 2005, 10:59 AM
Has anyone other than myself ever made a fitted barrel bushing for a Browning HP ? Yes they do have a bushing which is screwed in.

RickB
February 16, 2005, 12:53 PM
I don't think all HPs have a separate bushing. I have a Mk. III, and I see no evidence of a separate part. If it is separate, it's not readily removeable.