Barrel-Cylinder Gap

[smoothshooter]

A few days ago I bought a new Smith .22 revolver with the 3" barel. When looking it over, I noticed the barrel-cylinder gap looked rather wide, I would guess about .020".
When I commented on the wide gap, the rather knowledgeable guy behind the counter told me that Smith & Wesson now considers barrel-cylinder gaps up to .030" (!) to be within acceptable specs. I have always preferred a .003" to .006" gap.

I was under the impression that one of the reasons ( besides cost savings ) that Smith has gone the barrel shroud route was to make it easier for production workers/machinery to be speeded up while making adjusting the gap easier.

Anyone know anything about this?

 

[CH4]

We all like a gap of .003-.006! I heard .01 was the new acceptable Gap.

 

[BLUEDOT37]

... the rather knowledgeable guy behind the counter told me that Smith & Wesson now considers barrel-cylinder gaps up to .030" (!) to be within acceptable specs. I have always preferred a .003" to .006" gap.

Sadly, the counter guy doesn't know what he's talking about.

S&W used to consider .010" as an acceptable max. but changed it to .012". Most consider .006-.008" gap as maximum, with .003-.006" as preferred.

I've gotten new S&W revolvers with B-C gaps as bad as .011" & as good as .003". My new 66-8 snubby has a .003" gap.

.

 

[diggler1833]

Seems like another example of a gun counter commando spreading misinformation with every breath.

I second BLUEDOT's information on what S&W considers to be an acceptable max.

My personal S&W revolvers range from .002 to .009. Surprisingly the few new ones I've purchased have all been .006.

 

[gnystrom]

I just checked all my S&W's and .003 was the norm with none over .004.
My Kimber K6S checked in at .0015.

 

[dwhite]

I just got my new 66-8 back from warranty work on Friday. Amongst other things I complained about the wide-ish cylinder gap at .010-.011 and burrs on the crown.

They replaced the barrel (probably because of the burrs) and the new cylinder gap is .003. Perfect!!!

As the old gap was in-spec, I doubt they would have replaced/refitted the barrel just for that. Regardless I'm happy now.

p.s. It shot fine with the .010 gap; but it was one of my dirtier guns. We'll find out in a couple of hours how this new gap performs.

 

[riverrat38]

I just got my new 66-8 back from warranty work on Friday. Amongst other things I complained about the wide-ish cylinder gap at .010-.011 and burrs on the crown.

They replaced the barrel (probably because of the burrs) and the new cylinder gap is .003. Perfect!!!

As the old gap was in-spec, I doubt they would have replaced/refitted the barrel just for that. Regardless I'm happy now.

p.s. It shot fine with the .010 gap; but it was one of my dirtier guns. We'll find out in a couple of hours how this new gap performs.

I just got my new 66-8 snub back on Friday also. It was "venting" in S&W's terminology. Spitting in mine!
The BC gap was a nice .004 inch.
The repair slip says they cut the forcing cone and repaired the yoke. I think the chamber to barrel alignment was not good enough, and caused the "venting". This would not be a timing issue, but the chamber being either too high or low, with respect to the barrel. A timing error would make the alignment off left or right.
The original forcing cone was more of a suggestion of a "cone". The rifling was still evident at the very rear of the barrel.
I think the 66-8's are a little dirtier due to the need to modify the gas ring to avoid cutting the bottom of the rear of the barrel flat on the bottom. Probably a good trade-off.
Off to the range tomorrow.

Best,
Rick

 

[.455_Hunter]

Cylinder gap is the first thing I check on a wheel gun, followed by lock-up then endshake. If we are good to on all three (kinda hard these days with both Smith and Ruger), then more detailed inspection occurs.

It's a sad state of affairs when a brand new 2017 production magnum wheelgun from S&W, Ruger, Charter or Taurus has a much larger cylinder gap than a wartime emergency 1916 production Webley Mk VI chambered in low pressure .455.

 

[gumpys]

I prefer at least .006 Owned plenty of .003 and .004 guns that after 100 plus rounds would bind up. No thanks

Sent from my LG-H910 using Tapatalk

 

[riverrat38]

My Speer No.14 Manual recommends .008 inch as a good maximum, but says that up to .012 inch is industry standard.
They seem to be concerned that excessive gaps can cause stuck bullets, due to loss of velocity.

Best,
Rick

 

[SP45]

as I recall factory standard back in the 80s was .005 to .010. I know when they tried to get it to tight down to .002 they had problems with cylinder bind. I have seen as high as .015. I have also seen where it is different depending on which side you measured from so obviously the barrel shank was not cut straight, that is if the cylinder was turning true.

 

[smoothshooter]

A few days ago I bought a new Smith .22 revolver with the 3" barel. When looking it over, I noticed the barrel-cylinder gap looked rather wide, I would guess about .020".
When I commented on the wide gap, the rather knowledgeable guy behind the counter told me that Smith & Wesson now considers barrel-cylinder gaps up to .030" (!) to be within acceptable specs. I have always preferred a .003" to .006" gap.

I was under the impression that one of the reasons ( besides cost savings ) that Smith has gone the barrel shroud route was to make it easier for production workers/machinery to be speeded up while making adjusting the gap easier.

Anyone know anything about this?

Have been dealing with the previously- mentioned gun shop guy for over a year, and he has never said anything previously that I have found to be incorrect. He was not happy about what he said Smith was doing.

Shot the new revolver this morning, and had to stop after about 40 rounds. Every shot sprayed lead fragments back into my face on the left cheek along the lower left edge of my glasses, very consistently in an area about 2" across. The was very odd-same place, every time. Painful too.

Looks like this gun is going back to smith for a second time.
I was in the process of buying it three weeks ago when I noticed the barrel was screwed into the frame too far, and was not clocked in right. When looking down the sights I noticed thefront sight and rib tilted to the left. The gun store immediately shipped it back to S & W for warranty repair, and I went back and picked it up at the store the day it was returned ( 3 days ago).
Also, this barrel shows no sign of a noticeable forcing cone, and the rear end of the barrel appears to have been just cut off, with no deburring at all.

 

[BLUEDOT37]

I just got my new 66-8 snub back on Friday also.
The repair slip says they cut the forcing cone and repaired the yoke. I think the chamber to barrel alignment was not good enough, and caused the "venting".
The original forcing cone was more of a suggestion of a "cone". The rifling was still evident at the very rear of the barrel.

Sounds about like my FC was. Very short & shallow. Historically I've found the 2-piece barrel revolver to have good FCs on all of my others.

I believe the FCs are formed when the EDM/ECM rifling process is done on the 2-piece barrels, unlike on the one-piece barrels. Mine had what looked like faint "rifling" in the FC too.

The diameter of the FC was way too small on mine also. Smaller than the bullet's .357" dia. I believe that's what caused the spitting, not the alignment.

See my post, with pics, about it in Issues with my 66-8 2.75" :
http://smith-wessonforum.com/139663997-post59.html

.

 

[Dpris]

If the gun's spitting excessively & you have an almost non-existent forcing cone, it's not a matter of chambers being out of alignment.

As I mentioned elsewhere, the new 66 snub sample here was shaving bad enough to jam the cylinder four times with one load.

A range rod showed all six chambers in perfect bore alignment.

With at least a dozen reports of bad cones I've seen in the last three weeks, this does not appear to be a rare occurrence.
Denis