Shimming a M1903 barrel

[purple]

I have a couple of new, un-installed barrels, one a HS 9-44, the other a SA 8-44. I want to install one of them on a 900,000 range SA receiver, but find that they both time up even with the witness line on the receiver when hand tight. These barrels time up to a hand tight position of 18 and 20 degrees off vertical index on a Remington M1903 receiver, so they appear to be within spec for installation.

I've inserted a .003 piece of shimstock between the barrel shoulder and the face of the receiver and see that this would probably provide enough draw for one of the barrels to be installed on the SA receiver.

When tightened to the fully indexed position by hand a bolt will not close on a "go" gauge, so I should be OK for headspace after finish reaming. There is also sufficient clearance between the bolt safety lug and the rear bridge of the receiver. There is a bit of setback of the bolt lug seats in the receiver but it is otherwise sound. I don't think I'll be able to get a better fit by trying yet another new barrel on this receiver, so am thinking about trying to install it with a washer-style shim. Has anyone else done this with a new barrel? Results?

[m1903rifle]

I have heard of some people using a small hammer to upset the barrel shoulder to get the proper "draw" instead of the shim washer.

[ClaudeH]

I have heard of some people using a small hammer to upset the barrel shoulder to get the proper "draw" instead of the shim washer.

I've also read of chucking the barrel in a lathe and working the area ahead of the shoulder with a steel roller.

[1903shooter]

I have found over my years of collecting and working on 1903 rifles that a lot of (if not all) National Match rifles have a round shim between the face of the receiver & the facing shoulder of the barrel. On close examination of the receiver it appears that the arsenal faced the face of the receiver so that was perfect mating surface between the barrel and receiver. So it is possible that you have a receiver that was originally on a NM rifle. Or possibly a receiver that someone found the need to reface the receiver. In either case all you have to do is find a suitable round shim. There used to be a guy on ebay that sold them but that was several years ago. If I remember right he was selling shims that were used on hobby trains??? I just checked and found the receipt from the last set of shims I bought. Here is the information you need to get a set of shims. A MAIN HOBBIES 349 Huss Drive, Chico, CA 95928 1-800-705-2215, Model KYO96646, Kyosho 12x15mm Shim Set, the price in 2007 was $5.25 plus $3.18 shipping The set included 10 shims. They also have a website AMAINHOBBIES.com

[chuckindenver]

peen or rolling the shoulder is you best bet..
avoid shims...

[purple]

I have found over my years of collecting and working on 1903 rifles that a lot of (if not all) National Match rifles have a round shim between the face of the receiver & the facing shoulder of the barrel. On close examination of the receiver it appears that the arsenal faced the face of the receiver so that was perfect mating surface between the barrel and receiver. So it is possible that you have a receiver that was originally on a NM rifle. Or possibly a receiver that someone found the need to reface the receiver. In either case all you have to do is find a suitable round shim. There used to be a guy on ebay that sold them but that was several years ago. If I remember right he was selling shims that were used on hobby trains??? I just checked and found the receipt from the last set of shims I bought. Here is the information you need to get a set of shims. A MAIN HOBBIES 349 Huss Drive, Chico, CA 95928 1-800-705-2215, Model KYO96646, Kyosho 12x15mm Shim Set, the price in 2007 was $5.25 plus $3.18 shipping The set included 10 shims. They also have a website AMAINHOBBIES.com

Thanks for the detailed reply. I see they still list this set. They don't specify the thickness of the shims though, so I'm assuming that they came in a variety of thicknesses. Were you able to use one of this set of shims to do a barrel installation and how did that work out?

I know about peening or rolling the barrel shoulder but this means removing the fixed rear sight base and then re-installing it. Peening with a hammer isn't an exact process and I'm concerned about getting a uniform amount of metal displacement around the shoulder by doing this.

[chuckindenver]

once again...take the time to understand how square threads and the shoulder work..
i peen the shoulder all the time, and my results speak for themselvs..
so...since you wont take the time to search the posts.. ill fresh it up.
with square apex threads, and a shoulder.
most of the crush pressure is at the shoulder, and very little on the threads...the shoulder crush is normal, after being installed and removed the shoulder can peel back so to speak, bring the shoulder foward.
by peening the shoulder evenly, all your doing is bring some of the crush pressure back on the edge so that you can get at least 35 pounds of pressure on an index..
a washer, or shim..will give you a false crush, as well as push your headspace out. as your not restoring the crush, only pushing the barrel further out.
i have never heard of or saw a NM rifle that had a shim. the only shims iv seen were installed my someone other then the miltary, and every one that was shimmed, shot bad, and had headspace issues.

[purple]

In this case I'm dealing with a new, never installed barrel so the original shoulder crush factor would still be present. If I were to go the shim route I'm assuming that the shoulder would crush down on the shim. I'm thinking that headspace might be OK with a .003 or .004 shim as the bolt will not close on a go gauge when the barrel is put at vertical index by hand.

I'm reluctant to dick around too much with a new and pretty pricey barrel. No doubt I can locate another receiver which would be better for this installation.

[chuckindenver]

if you have mulitple barrels that over index , likely the issue is the receiver..i would locate another..
iv seen some that have been faced pretty hard.
all thats need in a match facing, is just to square, just a touch, sometime the barrel shoulder will need more...but never take off so much it wont index right.

[chuckindenver]

if you must use a shim..use brass or copper so that it crushes with the shoulder.
i still think removing the sight base, peening or rolling the shoulder, isntalling the barrel, and the installing the rear sight base, is the best fix for your issue.
just a bit more work..but worth it in the end, it will be safe, and likely will shoot very well.

[Dave in NGA]

Original shims are made of steel and measure;
OD = 1.253"
ID = 1.035"
thickness = 0.006"

based upon those I purchased many years ago and have used on a couple rebarrel jobs.

[purple]

Different rifle, different barrel thread, but the Brits issued 3 different steel shims or breeching washers for use when re-barreling the No4 Lee-Enfield. They came in .002, .003 and .004 thicknesses with the stipulation that shimming shouldn't exceed .004. The old gray cover NRA booklet for the M1903 also discusses the use of shims when re-barrelling the m1903.

[chuckindenver]

V threads and shims work well, square threads and a shim...no so much..
keep you self on the subject...so facts dont blur over..
iv rebarreled more 1903s then most.. my info isnt from someone elses book.

[Punch the Clown]

I use a shoulder roller Like Chuck suggests, but If you want shims they are available on the FAL Files.

http://www.falfiles.com/forums/showthread.php?t=310575