66-1 cylinder gap

[Harry Stone]

I have an old 66-1 that I just love. I bought from a friend of a friend that needed the money and didn't have any interest in guns (he inherited it) and I was glad to rescue it from sitting in an attic or something.

Here's my question. There is a bit of front to back cylinder play in this gun. I measured the cylinder gap with the cylinder all the way back and it is about .007, a little more than half that by eyeballing it without pushing the cylinder back. By back I mean pushing the cylinder towards the hammer.

Should this amount of slop be fixed, or am I worrying about nothing? I haven't fired it much but I've never had any problems with it.

I take that back, I have one problem with it, I can't shoot a snub very well.

Also, if anyone knows a year it was made I'd love to know. The serial prefix is 32K.

Thanks for any help.

 

[dfariswheel]

To determine the amount of end shake in the cylinder, gently push it forward and measure the gap between the cylinder and the barrel with a feeler gage.
Then push the cylinder back toward the hammer and measure again.

The difference is the amount of end shake.
On S&W revolvers, the approximate maximum allowed is .006" before repair is needed.

 

[enfield]

Ask your DOB question on http://smith-wessonforum.com
and you'll get an answer.

 

[Pistol Toter]

1978/1979 for s.n.'s 25K0001-56K9999

 

[Confederate]

Using full throttle magnum ammo, the end shake will probably get worse. The recoil pushes the cylinder back and sometimes forces the case back into the firing pin. Examine your primers and see if any of them are pierced, and examine the forcing cone for any excess wear.

Chances are, your end shake was the result of manufacture. Smith quality control at the time was a bit of an oxymoron. Most gunsmiths could probably drop in a spacer and your problem would be fixed. If not, I'd return the gun to Smith & Wesson and let them fix it.

Just out of curiosity, what is your barrel length?

See this Smith & Wesson forum topic.

Also consider Ron Powers' end shake bearings, which is a huge seller.

 

[lawboy]

I am a little confused regarding whether we are talking about end shake or cylinder gap. the two are different.
Cylindar gap is the amount of space between the cylinder face and rear of the forcing cone when the revolver is cocked.
End shake is the amount of fore/aft movement of the cylinder when measured as described in a post above. Normal cylinder gap in modern revolvers is from .002 to .008 or so. However, it is not uncommon to find guns in new or excellent condition with more gap that shoot very accurately. Contrary to some popular opinion, cylinder gap results in negligible velocity loss regardless of how much gap you have. You will run into safety problems with excessive gap long before it becomes a velocity loss issue.
On the other hand, excessive end shake can cause the gun to batter itself into poor condition relatively quickly when heavy loads are used. End shake is corrected with shims that are added to the cylinder crane at the front of the gas ring I believe. DO NOT LET ANYONE STRETCH THE YOLK, CRANE OR ANY OTHER PART OF THE GUN TO CORRECT END SHAKE!

 

[Harry Stone]

It's a 2 1/2" barrel. It makes quite a boom with .357 loads. I'll probably only shoot .38 special out of it from now on.

 

[Confederate]

Bummer. If you can find a good deal on a Ruger Speed-Six, go for it. I got mine in a .38 Spc with a 3-inch barrel and then had the chambers rethroated for .357 by a gunsmith who gave me exact specification work. The action is like glass, too.
.

 

[dfariswheel]

"DO NOT LET ANYONE STRETCH THE YOLK, CRANE OR ANY OTHER PART OF THE GUN TO CORRECT END SHAKE!"

Sorry, that's wrong.
The S&W factory approved method is to stretch the yoke barrel.
The NON-factory approved method is to trim and square up the yoke barrel then use hardened stainless steel bearing washers to correct.
These hardened bearings are dropped inside the cylinder, then the yoke is installed.

There are two methods of stretching the yoke barrel.
The S&W factory method is to insert a hardened steel stud into the barrel and peen the rear. The barrel is stretched slightly over-size, then trimmed to square up the end.

The non-factory stretch method uses a modified tubing cutter. A tubing cutter's wheel is rounded off so it presses a groove into the tube instead of cutting it.
A hardened stud is inserted into the barrel and the modified cutter is used to press a groove into the barrel, stretching and lengthening it.
Again, the end is trimmed to square it up and fit it.

 

[JNewell]

IIRC, Kuhnhausen comments favorably on the use of the washers to eliminate endshake because it increases the bearing area. (Someone correct me if I'm remembering incorrectly.)

 

[Confederate]

The only problem with bearing washers is that they can open up the cylinder gap or, alternatively, increase headspace. When the cylinder is at rest in the revolver, the cylinder gap may be .006. Push it back with your thumbs and it could open to .009 or .010. By inserting a bearing washer, the endshake can be eliminated, but then the gap may open up. If corrected the other direction, the headspace may be increased, resulting in misfires.

I had a gun with that kind of problem a number of years ago. It was on a Taurus or an Astra, can't recall, but I got the gun back with excessive cylinder gap. I sent it back again and soon got it back with too much headspace (but the b/c gap had been corrected). The people doing the work on the gun couldn't fix both problems at once because I guess they either weren't trained to do that or they thought they could get away with doing what they did. I ended up just getting rid of the gun.

I've never seen a Ruger with endshake, but I do have a little .22LR Rossi with some endshake. It misfires every now and again, but that could be worsened by a lighter spring I put in. When a gun has endshake, the firing pin can actually push the cylinder a little forward. Of course, when the gun goes boom, the cylinder is pushed back and the b/c gap opens slightly. It's not a great problem to have, nor apparently easy to fix.