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-   -   Commercial barrel turns past index point before getting tight. (http://forums.thecmp.org/showthread.php?t=276440)

krdomingue 02-06-2021 07:41 PM

Commercial barrel turns past index point before getting tight.
 
I have commercial barrel that was reportedly taken of an SA Inc M1A rifle that I am attempting to put onto a Bula receiver. The barrel turns about a 1/4 inch past the index point before it starts get tight. Is there a proven method to shim the barrel or is it a lost cause?

nf1e 02-06-2021 07:50 PM

You can roll the shoulder. Compress the barrel metal that contacts the front of the receiver to tighten it up. Very simple process and no need for shims.

krdomingue 02-06-2021 08:17 PM

Quote:

Originally Posted by nf1e (Post 2012785)
You can roll the shoulder. Compress the barrel metal that contacts the front of the receiver to tighten it up. Very simple process and no need for shims.

I will try that. Thanks

gjungle56 02-07-2021 05:52 AM

If me, I would give barrel a quick head space check at approximate index. If I figured right it'll take a roll equaling about .008 just to get to hand tight index and then yet more for the barrel to be tight. I've always wondered what is the objection to a shim? After all, the Rem 700 recoil shoulder is actually a shim. As a tool maker, I shimmed chipped carbide die parts all the time, standard op procedure, with no ill affect. I have shimmed barrels that had out of true shoulders, and then cut true, for proper index. with no ill affect. I do make the shim out of the hardened blue stock.

krdomingue 02-07-2021 12:27 PM

Quote:

Originally Posted by gjungle56 (Post 2012902)
If me, I would give barrel a quick head space check at approximate index. If I figured right it'll take a roll equaling about .008 just to get to hand tight index and then yet more for the barrel to be tight. I've always wondered what is the objection to a shim? After all, the Rem 700 recoil shoulder is actually a shim. As a tool maker, I shimmed chipped carbide die parts all the time, standard op procedure, with no ill affect. I have shimmed barrels that had out of true shoulders, and then cut true, for proper index. with no ill affect. I do make the shim out of the hardened blue stock.

I have no objection to using a shim other than making one is beyond my knowledge/capability. I would need to find a commercially available shim that would fit.

jmm 02-08-2021 10:25 PM

Doesn't adding a shim increase the headspace on a previously reamed chamber? :confused:

gjungle56 02-08-2021 10:30 PM

Yes it will, so will rolling shoulder

4gun-drill 02-08-2021 10:42 PM

Quote:

Originally Posted by gjungle56 (Post 2013604)
Yes it will, so will rolling shoulder

No, it won’t. If the barrel is at TDC the headspace won’t change unless you go a full revolution one way or another.

nf1e 02-09-2021 06:45 AM

Quote:

Originally Posted by 4gun-drill (Post 2013608)
No, it won’t. If the barrel is at TDC the headspace won’t change unless you go a full revolution one way or another.

Rgr that!

Ted Brown 02-09-2021 03:16 PM

There is no correlation between various commercial receivers and commercial barrels that insure proper head space when switched.


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