S W Model 66 Weird Cylinder Gap

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Chris Fett

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Hi,

I'm contemplating the purchase of a S & W Model 66-2 with a 4" (prohib) barrel.

The revolver I'm looking at is in very nice shape, no forcing cone or top strap erosion, the end play & cylinder wiggle is within spec and the sideplate screw heads aren't messed up so doesn't look like anyone who didn't know what they were doing went inside. The 66 is a K-frame.

The issue though, is the cylinder gap. Smith & Wesson says anything from 0.004" - 0.010" is acceptable. I like to see no more than 0.006" but in this particular handgun, the gap is practically non-existant (maybe 0.002") on the left side when looking down at the top of the gun with barrel pointing away BUT the gap is 0.005" on the right side...giving the impression that the cylinder is not parallel with the long axis of the gun.

The present owner says that that that forcing cones are ground side-to-side after the barrel is threaded in place so out-of-square is normal. Someone else thinks this may be the result of slamming the cylinder shut with a flick of the wrist (Hollywood style). I'm not sure how slamming the cylinder would cause misalignment of the cylinder...if anything it'd damage the ejector rod...I don't think the yoke (AKA crane) would plastically twist out of alignment and besides, the gap is on the right side not the left...a rotation of the cylinder would cause the gap to be on the left side (I would think)..

Any ideas on how this gap difference happened and is it a cause for worry ?
 
You don't mention whether you're pushing the cylinder back, when measuring the "gap" There's usually a couple of thou movement there.

One of the most accurate revolvers I own and shoot is a Mod 66 that has .003 gap, but only when the cylinder is pushed back

That gap measurement isn't written in stone, IMHO, for safety reasons but to make sure the cylinder and the mouth of the forcing cone don't bind when returning the cylinder to battery position.

To have such a difference, over such a small distance, I believe that much cylinder off the axis of the bores would be eyeball visible.

If it's locking up well after closing it should be OK.

S&W revolvers have a very tight tolerance between the body of the crane and the frame.

I have seen these revolvers with frames twisted after re barreling and they will show a very visible gap at the crane/frame juncture. Usually the alignment also visible to the naked eye and the cylinder binds when swung into battery.

Your post got me curious, so I pulled out a couple of my factory barreled S&Ws and a Taurus. They varied anywhere from .002 to .006. The Taurus was the tightest and the face of the forcing cone had a slight angle on it. It looks to have been done purposely. Maybe stoned at the factory during fitting, to make sure the cylinder clears as it swings into battery??

Won't make any difference to the function of the forcing cone at all.
 
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End shake? much? not a big deal, where you run into trouble is carbon build up and the cylinder dragging, . a good stoning would straighten it out.
As a 12-6 66 model we are talking about or less 400.oo I would think, so just shoot the hell out of it and clean when needed, I have K frames , but not a 66 to look at The 19 has end shake, the 14 has none, both shoot tight groups, I don't always, but usally 1 1/2"-2" DA
 
The Bbl tenon threads & forcing cone was machined prior to Bbl installation...not after the fact.

Buy it & Shoot it!!

When you shoot it enough to see flame cutting in the underside of the top strap above the cone....shoot it some more.....the cutting will stop.
 
Is your revolver spitting lead ?
If not, nothing to worry about.
If yes, get an 11 degree reamer (if I remember 40 years ago memories) and rework the cone.
There was also a tool consisting of a stem introduced in the barrel, with the forcing cone side fitted with a cylinder whose flat face had cutting blades; by rotating the stem, the cutters "surfaced" the barrel mouth.
 
The yoke certainly could be bent from abuse like flicking the cylinder closed, or dropping the revolver. The alignment can be checked easily with a range rod. Now if you do not have access to one, you could ask to test fire the gun first. If it's accurate and doesn't bind or spit lead, all is good.
 
Clean the cylinder face & the forcing cone face. Put some black magic marker on the cylinder face. Load six snap caps or 6 empty 38spl cases into the cylinder. Close & dry fire all 6. Open the cylinder & check for rubs or scrapes on the cylinder face. If you find some, it could be that the force cone is not concentric, & is rubbing.
If this is the case then the force cone must be trued up.
 
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