Rimfire cylinder binding, pic with post.

[GGF]

I'm having a problem with my Mod 34.
After firing 6 -12 rounds the cylinder binds up to where it doesn't rotate or open easily.

I did a search about cylinders binding and I'll tell you what I've ruled out.

1. It's not dirty. I've took the cylinder out, took it apart & soaked it, brushed the chambers and cleaned behind the extractor star.

2. Tried different ammo.

3. Ejector rod is tight & straight.

4. No carbon/lead build-up on the forcing cone.

5. Locks up normally with unfired rounds in it. ( until you fire a few )

This doesn't look like the recoil shield on my other rimfire revolvers ..




... see where the case heads are rubbing the at the top of the shield.


Your thoughts and suggestions for a fix is very much appreciated.

GF

 

[Jim K]

It looks like the frame mounted firing pin (used in all modern S&W rimfires) is not retracting fully or is too long. Is there any protrusion you can feel and is the recoil shield otherwise smooth? Not sure why a problem like that would wait 6-12 rounds to show up.

An uncommon cause of cylinder binding is too tight a barrel-cylinder gap that closes up as the cylinder heats up. That seems pretty unlikely with a .22, but it does match what you say about 6-12 rounds. Then while the shooter messes around trying to free the cylinder, it cools down and all is well. So check the b/c gap; it should not be less than .004". Under that, and I would expect that is the problem.

Jim

 

[BBBBill]

I would expect the heating/expansion problem more with a 357/thin cylinder walls, but who knows.......

 

[243winxb]

The face of the cylinder may have high spots. My M17 did. Easy fix for a good gun smith. Check with a feeler gauge. Should be .004" minimum gap between barrel & cylinder.

 

[rcmodel]

The top chamber with the grey ring around it in the photo suggests there is something different about it then the others.

Maybe a photo lighting trick?

Maybe a protruding sharp edge in the chamber throat catching fouling and rubbing on the barrel as it gets dirty?

Can't tell from the relatively poor quality cell-phone picture.

But look at it closely, again.

rc

 

[GGF]

"Check with a feeler gauge. Should be .004" minimum gap between barrel & cylinder. "

I'll have the headspace checked, that has been mentioned when I've shown in to those more knowledgeable that me.
Also There looks like a burr in the face of the recoil shield. At the edge of the clearence cut for the ratchet around the hand window.

I don't know - looks like I need to send it to a compentent gunsmith and not mess with it myself!

GGF

 

[rcmodel]

Have you tried it with more then one brand of ammo?

Any bur on the recoil shield can easily be removed with a fine stone or needle file.

If it doesn't look like it belongs there?
Carefully Stone it off smooth.

BTW: the round circle with the finish worn off is normal on a well used gun.
It't where the case heads impact the recoil shield every shot.

rc

 

[mnrivrat]

That hand window bothers me as it looks like more than just a bur. Have you checked timing and lock up ? Shaved lead from poor change up and lock up will build up fast on the back of the barrel to cause cylinder binding.

Could be a number of things causing problems, I think it's time to send that to factory service, or a good revolver smith.

 

[claiborne]

Here's a Thought

I recently bought a used model 63 with similar symptoms. Whether actually firing or pulling the trigger on empty chamber, as it rotated, the cylinder was binding. I cleaned, re-cleaned, and re-re-cleaned. Nothing... I finally busted out the magnifying glass and started poking around.
Guess what I found? Very tiny brass shavings that were stuck under the extractor, out of sight, even with the extractor pushed out. I had cleaned under there on each of the previous cleanings. After I cleaned the shavings out the binding problems disappeared.

 

[rcmodel]

Yes!

Imagine that!

About 99% of the time that is what causes this sort of problem.

rc