Interesting thoughts on barrel/cylinder gap

[Stantheman86]

I found an article about shooting blackpowder rounds through Peacemakers, obviously "unmentionables" but the information applied to percussion revolvers

The writer claimed he had revolvers with .002 b/c gaps that ran perfectly fine for 100+ rounds before gumming up....because the fouling on the cylinder face doesn't build up enough and only the fouling blown down into the cylinder pin started to bind the gun up.

I had thought , previously that .002 would be way too tight. It seems that a smaller gap actually reduces fouling to an extent

 

[alcessapiens]

It scrapes off as the cylinder revolves.

 

[45D]

It scrapes off as the cylinder revolves.

An open-top platform is going to do that anyway.
I've been setting open-top endshake at .0025" - .003" for 12 / 13 yrs. Makes for not only a much cleaner shooting experience but more efficient use of powder.

Mike

 

[alcessapiens]

An open-top platform is going to do that anyway.
I've been setting open-top endshake at .0025" - .003" for 12 / 13 yrs. Makes for not only a much cleaner shooting experience but more efficient use of powder.

Mike

My Blackhawk .357maximum (in84) would quickly burn holes through a thick leather leg pad when shooting creedmore for 200m silhouette. Got gap space reduced to .018. Problem solved.

 

[Flint62Smoothie]

Got gap space reduced to .018. Problem solved.

Uhhh … is that 18-thousands? Or is the decimal point off?

FWIW a typical early S&W had a gap of 0.004” where a typical current one is about 0.006”. I recall from my gunsmithing days that for a Ruger (cylinder pushed forward) was a 0.003" minimum to 0.008" (pushed backwards) or maximum spec.

 

[M. De Land]

I found an article about shooting blackpowder rounds through Peacemakers, obviously "unmentionables" but the information applied to percussion revolvers

The writer claimed he had revolvers with .002 b/c gaps that ran perfectly fine for 100+ rounds before gumming up....because the fouling on the cylinder face doesn't build up enough and only the fouling blown down into the cylinder pin started to bind the gun up.

I had thought , previously that .002 would be way too tight. It seems that a smaller gap actually reduces fouling to an extent

I always have set them at ..004 to .006 but after hearing what 45-D does I'm going to set them tighter as well. The trick is to get them the same around the clock (square with the barrel face) and not just tight at the top in open frame guns.

 

[Stantheman86]

I always have set them at ..004 to .006 but after hearing what 45-D does I'm going to set them tighter as well. The trick is to get them the same around the clock (square with the barrel face) and not just tight at the top in open frame guns.

I have a pair of Pietta .44 Navies that I dropped full flute cylinders into. The b/c gaps on both let a .002 feeler gauge slide in , barely. The new cylinders work but the gap tightened up with them. These may be awesome guns to shoot 777 through .

I'm going to test fire them and if they work , I'll just leave them. If they bind up I'll touch the forcing cone with a file until an .003 gauge goes in.

I've touched up forcing cones on unmentionables and cap and ballers over the years, usually just to clean up sloppy factory work and open them up a .001 or so

 

[45D]

I always have set them at ..004 to .006 but after hearing what 45-D does I'm going to set them tighter as well. The trick is to get them the same around the clock (square with the barrel face) and not just tight at the top in open frame guns.

Yes, with practice and going slow the equal opening is relatively easy to accomplish. I remember years ago reading an article in Guns & Ammo (I think) which was a test for velocity changes as the barrel/ cylinder gap was closed. It seems no real change happened until it got to the less than .003" then things changed rapidly. Of course the problem with that on revolvers with a gas ring or bushing would be the build up of fouling on the cyl face causing cylinder drag on the f.c.
The beauty of the open-top without the gas ring/ bushing allows it to be somewhat "self cleaning" as the cyl face contacts the f.c. during each cycle.

Mike

 

[Art Caputo]

I have found the sweet spot to be .002”-.0025”(go/no-go, and perfectly squared to the faces) on both my black powder, and modern revolvers. Regularly brush/clean the cylinder face and the barrel breach/forcing cone, free of any lead/carbon build up.

 

[Stantheman86]

I have found the sweet spot to be .002”-.0025”(go/no-go, and perfectly squared to the faces) on both my black powder, and modern revolvers. Regularly brush/clean the cylinder face and the barrel breach/forcing cone, free of any lead/carbon build up.

I touched up the two Piettas to where the .0025 slips in but the .003 doesn't really fit

Some chambers are probably an immeasurably small amount tighter just due to cylinder face variance , but they're Piettas not Korths

 

[Bunk]

An open-top platform is going to do that anyway.
I've been setting open-top endshake at .0025" - .003" for 12 / 13 yrs. Makes for not only a much cleaner shooting experience but more efficient use of powder.

Mike

I have a couple of "Goon's guns" and they run so reliably it is almost boring to shoot them...almost but not quite.
But they get shot a lot and simply work.
Bunk

 

[Stantheman86]

I'm having fun learning how to make my own guns work 100% reliably, it's very satisfying

I know I got it right when I can load up and let someone with little to no experience with cap and ballers roll through a cylinder , without a cap jam, the cylinder gumming up or a cap not popping because they can just shoot it like a cartridge gun