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B/C gap measuring?

Posted: Thu Jan 24, 2013 12:19 pm
by ruger22
Looking around online, I get fifty different ways to check the barrel/cylinder gap on a revolver. With the cylinder static, pushed forward, pushed back. With and without cartridges in the chambers. Etc., etc.. I think some people only do it during a certain moon phase.....

I've always understood that with an empty cylinder pushed forward, that was the B/C gap. Pushed back was headspace, and the difference was end shake, or cylinder play. Or maybe I've read so much, I'm confusing them now?

My four revolvers are such:

Bearcat one, .003 forward, .005 back, endshake of .002.

Bearcat two, .005 forward, .007 back, endshake .002.

LCR-357, .004 forward, .008 back, .004 endshake.

LCR-22, .003 forward, .008 back, endshake .005.

I had a Single-Six that measured .003 and .007 after Ruger re-barreled it to fix a .012 B/C gap.

And with countersunk rim chambers like the Bearcat, I don't think the measurement is right with the cylinder pulled back, since the cylinder has a raised rim on the back that contacts the recoil shield?

Posted: Fri Jan 25, 2013 1:24 am
by Hardball
With trigger held in fired position.

Posted: Fri Jan 25, 2013 6:57 am
by Bullseye
I saw that you have gotten a very thorough explanation of this question from a revolver smith on another forum and I'm sure your satisfied with the knowledge gained. I will only add that most manufacturers have their own tolerances for end shake and B/C gaps and there isn't one set of go-no go specifications that covers all.