.22LR fired case head bulging

[Earl Keese]

A buddy of mine has an old Iver Johnson revolver. Not a nice pistol by any means, but it means something to him. He's had some light strikes and took it to a local gunsmith...4 years ago. Anyway, he got it back untouched and we shot a few rounds to see what he was talking about. No light strikes, but after 5 or 6 shots the cylinder hung up and wouldn't advance to the next round. Got it apart and the problem was the bulging of the case heads. I know the hammer is striking too far out on the rim, but what causes the bulge? I've never seen it and he didn't recall the issue from before. The ammo came from an open box of Fed Automatch that works great in my Kadet.I can feel the slightest bit of end play in the cylinder. Would that be the likely cause? Thanks for looking.
[ IMG ] [/img]

[1SOW]

Sheer guess:  Cylinder alignment off,  causing the offset strike and unsupported case when it fires?
Has he got any old fired cases from before the problem started?

[Earl Keese]

No old fired cases. By offset strike, what do you mean? The strike on the outer edge, or offset radially? I just stuck those cases back in the cylinder to make it easier to photograph, so they aren't perfectly aligned.
 The strikes on the outer edge I believe are due to him working on the hammer. He thought the hammer was worn down, causing light strikes so he built it up with a mig welder and reshaped it. I might be able to find him a replacement hammer, but the case support issue has me thinking maybe the gun should be retired. He's not overly concerned with fixing it, mostly a learning experience for me.

[copemech]

That thing probably was not built for High Vel. loads as the unsupported back end shows. Try some standard vel. and see how it does. There can be a lot of difference in pressures.

[ReloaderFred]

It looks to me like the revolver suffers from a headspace issue.  There is too much gap between the back of the cylinder and the pressure plate.  It's time to retire it.

Hope this helps.

Fred

[M1A4ME]

I was thinking the same thing (Fred is right).

If he really has to have it fixed (if it was mine I'd want it working, for old times sake if nothing else).  He might be able to have a bushing fitted into the front of the cylinder to push/hold the cylinder closer to the rear of the frame.

Keeping some lube on it would help prevent wear and protect the finish, too.

[Earl Keese]

Comments pretty much confirm what I was thinking. This one has a lot of miles on it. I think I'll re-blue it for him and he can put it up. Thanks again.

[SI VIS PACEM PARRABELLUM]

This is called end shake in revolvers and is pretty common across the brands. The excessive fore and aft movement of the cylinder can sometimes be corrected with fine shims between the cylinder and yoke. I've snugged up a couple of my old S&W's with shims made by Power Custom and they do work well.
Without actually physically seeing the old .22 it's hard to say if it could be repaired this way but judging from the pics it looks really well worn.

[Wobbly]

However, when you shim the cylinder to the rear to take up head space, the cylider-to-barrel gap opens up. It's a "Catch 22", no pun intended.

 

[SI VIS PACEM PARRABELLUM]

However, when you shim the cylinder to the rear to take up head space, the cylider-to-barrel gap opens up. It's a "Catch 22", no pun intended.

 

Yes I understand that. This is why when refurbing an old wheel gun you would address end shake before measuring the bc gap too see if the barrel needs to be set back and forcing cone recut. Setting a barrel back is a gunsmith operation and could be cost prohibitive on a gun that is well worn with no real value left to begin with.
Quite often you can remove all or most end shake and still be in spec on the bc gap though.

[Earl Keese]

Once again, this forum comes through and my education continues. The cylinder on this gun comes out for loading and unloading. I would think dealing with a shim would be a challenge.
 At some point I hope to acquire a DW revolver and a S&W 629. This info will come in handy for sure. I've always been unsure what is good/acceptable/bad when looking at used revolvers.

[M1A4ME]

However, when you shim the cylinder to the rear to take up head space, the cylider-to-barrel gap opens up. It's a "Catch 22", no pun intended.

 

Still excellent.  I think I just woke my wife up.  And the cat is looking at me funny, too.

[SI VIS PACEM PARRABELLUM]

Once again, this forum comes through and my education continues. The cylinder on this gun comes out for loading and unloading. I would think dealing with a shim would be a challenge.
 At some point I hope to acquire a DW revolver and a S&W 629. This info will come in handy for sure. I've always been unsure what is good/acceptable/bad when looking at used revolvers.

Endshake on an S&W was always considered excessive if it exceeded .002 and a good bc gap would be around .006-.008 but in recent years S&W as well as Colt and Ruger increased their maximum allowable tolerances to accommodate the use of CNC machines in place of good old hand fitting and their own shoddy overall workmanship.
Their are many good online sources for info regarding pre-purchase inspection of revolvers. The same inspection protocols  for used revolvers should also be used when buying new guns as well.
A very good piece of advice would be too not purchase a revolver online since there are too many things to inspect and too many things that can be wrong with it. handling the gun first is very much the way to go.