Bbl-Cyl gap

3rd Gen Neal · #1 04-20-2010, 11:09 AM

I have heard so many different opinions on this, the barrel to cyl gap, I wanted to ask what you guys consider to be ideal and excessive. My 28-2 N prefix is about .0085. Is that excessive?? My 29-2 is more like .005. Then my 686-6+ basically doesn't have a gap!! I'm not looking for imaginary problems with my weapons just curious. And if a revolver is overly gapped what is the result/solution?? Thanks everybody.

Nightowl · #2 04-20-2010, 11:19 AM

Factory standard is about .004 to .010. About .006 is probably the most recommended. Unless you are having problems with .0085, it is not worth trying to correct to .006 or less. The fix is to remove the barrel and turn the shoulder back so it will make one more turn, then the extractor rod has to be shortened and refit. I once had my 627 set back to .004 and had it hang up, so I had to open it back up to .006. I would not worry about it, at this point.

Gun 4 Fun · #3 04-20-2010, 11:21 AM

S&W specs used to be .004" - .010" as being within tolerance, but I have read not too long ago that it is now .004" -.012".
Most S&W's when actually measured will run in the neighborhood of .005"-.007", and will seldom be uniform all the way around the cylinder.

H Richard · #4 04-20-2010, 12:18 PM

I have a 17-4 that has from .001 to .002. I have not had any dragging problems, but do not shoot it extensively.

Gun 4 Fun · #5 04-20-2010, 12:52 PM

Quote:

Originally Posted by H Richard

I have a 17-4 that has from .001 to .002. I have not had any dragging problems, but do not shoot it extensively.

I have a 629 P&R that has .0015", and I haven't had any trouble yet either, though I thought I might. My F/A 83 will barely allow a .001" feeler gauge through, and I use top end cast loads all the time with no problems either.

dant · #6 04-20-2010, 04:02 PM

yes, close is better, until it actually rubs, and if you get ANY fouling ( lead build up) it can and will 'rub', if they get that close....we try and keep it around .004-.006"

jvmm · #7 04-20-2010, 10:48 PM

I just put a NEW barrel on my Mod 14 and measured the cylinder/barrel gap at .016!!!

Should.s I take it to the range for testing or get the lathe ready?? thanks

jvmm · #8 04-20-2010, 10:50 PM

I just put a NEW barrel on my model 14 and checked the gap...it is .016!!!

Should I go to the range for testing ot get ready to turn the lathe on? Thanks

Gun 4 Fun · #9 04-20-2010, 11:09 PM

A gap that large will usually cause spitting, and is not a good thing. I would tighten that up if at all possible. You will also lose some velocity from a gap that large.

In fairness, I need to mention that I have a very old S&W that has a .017" gap, and it doesn't spit. The fact that the chambers line up nicely with the bore when locked up is the biggest reason why, but I would still prefer it to be under .008".

jvmm · #10 04-20-2010, 11:53 PM

It's off to the range, I guess will give an AAR. Willbe using cast 148 WC with Bull.

bgrafsr · #11 04-21-2010, 10:31 AM

.016" is way to big of a gap. I would have the barrel shoulder turned back one complete turn, or at least enough to have the barrel draw up tight to the frame, and then use the lathe to cut the end of the barrel back so it stays square and you get a good gap of .003" to 004". If only turning the shoulder back one turn, you may not even have to shorten the extractor rod.