Cylinder to barrel gap
- Thread starter MR.G
- Start date
.004 to .006 is what you will usually find. Anything over .006 is excessive. Some revolvers have a gap as low as .002. Too loose and you get extra powder gas blowing out and maybe spitting lead. Too tight and dirt and powder residue could lock up the cylinder or cause it to drag. Premium, accuracy intended revolvers are usually tighter toleranced. My Experience!
In praise of small gaps...
My personal .38snubbie has a .002" gap. I like it like that. True, towards the end of a 50-rd box of ammo the trigger starts feeling gritty
but a quick wipe to the back of the barrel and front of the cylinder clears it up for another 30 or 40 rounds at least 
.
.38Spl from a 2" barrel is marginal stuff. I want all the velocity I can get. I keep it loaded with two 5rd speedloaders handy so in 15 rounds it's not going to gum up.
In a wilderness survival gun and a more serious caliber and barrel length, I can see going to .003" or even .004". More than that isn't optimal. More than .007" is a malfunction.
If you end up with one that's too tight, at .001" or you want more than .002", DO NOT send it back to the factory! I wouldn't. God only knows what it'll come back at.
Instead, if it was me, I'd take a fine-grit knife sharpening stone and very gently polish the back of the barrel. Go dead slow, keep it nice and flat, take light strokes and you'll get it to where you want. This is the easiest home gunsmithing fix there is, and will allow you to set the gap to YOUR needs.
Don't look at a "too tight" gun as a problem. If you find such a critter at your gun dealer, look at it as a wonderful opportunity to set the gap to perfection.
My personal .38snubbie has a .002" gap. I like it like that. True, towards the end of a 50-rd box of ammo the trigger starts feeling gritty
but a quick wipe to the back of the barrel and front of the cylinder clears it up for another 30 or 40 rounds at least ..38Spl from a 2" barrel is marginal stuff. I want all the velocity I can get. I keep it loaded with two 5rd speedloaders handy so in 15 rounds it's not going to gum up.
In a wilderness survival gun and a more serious caliber and barrel length, I can see going to .003" or even .004". More than that isn't optimal. More than .007" is a malfunction.
If you end up with one that's too tight, at .001" or you want more than .002", DO NOT send it back to the factory! I wouldn't. God only knows what it'll come back at.
Instead, if it was me, I'd take a fine-grit knife sharpening stone and very gently polish the back of the barrel. Go dead slow, keep it nice and flat, take light strokes and you'll get it to where you want. This is the easiest home gunsmithing fix there is, and will allow you to set the gap to YOUR needs.
Don't look at a "too tight" gun as a problem. If you find such a critter at your gun dealer, look at it as a wonderful opportunity to set the gap to perfection.
I hope that .10" is supposed to be .010". A gap of .10" would be the thickness of two dimes. I think .010" is on the high side, but I don't see any real problem, and I have fired guns with a lot more than that with no trouble. I don't know what S&W's specifications are.
One disadvantage of a too-small barrel-cylinder gap is that the cylinder will lengthen and bind if it becomes hot. I have had to relieve the gap in several CAS guns because they were binding up. One had a gap of .002".
If the gap really bothers anyone, there are still Nagants around.
Jim
One disadvantage of a too-small barrel-cylinder gap is that the cylinder will lengthen and bind if it becomes hot. I have had to relieve the gap in several CAS guns because they were binding up. One had a gap of .002".
If the gap really bothers anyone, there are still Nagants around.
Jim