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jimmy
August 28, 2000, 06:57 AM
I'm curious about the effect, if any, of irregular barrel/cylinder gaps on revolvers. On one of my revolvers I noticed that the b/c gap looked wider on one side than on the other. So, to occupy part of a rainy weekend afternoon, I measured the gap on it as well as on some other guns with a feeler gauge.

The gap whose difference I could see measures .004 on one side and .011 on the other. But most of the irregular gaps I found are less dramatic, measuring (left and right, respectively): .003 and .005, .006 and .005, and .005 and .007. I've also noticed gaps that differ on the top and bottom. Based on my sample, I'd say irregular gaps are the rule nowadays rather than the exception.

Measurements like these may reveal the care (or lack of care) that goes into modern revolver manufacture. But do they matter in any practical sense?

[This message has been edited by jimmy (edited August 28, 2000).]

Icopy
August 28, 2000, 08:40 AM
I noticed the same thing on my S&W N-Frame. It's going back to the factory for their free cleaning and check-up. I'm going to have them look at it.

George Stringer
August 28, 2000, 08:44 AM
Jimmy, before you can accurately measure the b/c gap you have to check the headspace. This is done by loading the chambers with fired cases making certain that no primers protrude and that there are no burrs around the firing pin hole and then measuring the gap between the case heads and the recoil shield. This measurement should not exceed .008". Regardless of this measurement you need keep the cylinder blocked forward. Either leave whichever feeler fit in place or replace it with a shim. Then measure the b/c gap. This should be at least .005" to ensure that the cylinder doesn't drag on the barrel. If the headspace doesn't change and you maintain the minimum B/C gap from chamber to chamber then you don't have a problem. George

jimmy
August 28, 2000, 01:19 PM
George--many thanks for the info. So, any irregularity in the gap does not matter as long as the headspace is okay and the b/c gap is a minimum of .005, properly measured. Interesting! :)