Big S&W 642 Problem

[popeye]

I have a 642-1 (no lock) that I bought new 6 mos ago and was unfired. Today i tried to fire some brass with newly loaded primers only (no bullet, no powder) in it and the cyl .locked up. took lots of finger strength to pull the trigger . Opened the cyl. and noticed that the primers are concave.Ran finger tip over the firing pin bushing and it is convex and above the face of the recoil shield. I do believe this is the problem. What do i do , send it to S&W or to a gunsmith to fix ? Has anyone else had this problem? Is this the same type of thing that the early 686 had? Empty, it dryfires OK. With loaded shells they will allow the cyl. to rotate . Clearance between cyl. rear and breach face is really tight. With cyl. loaded and closed I cannot see any light between case rear and breech face. I Pulled bullets and powder on factory ammo and fired with just primers and it locks up with primer flattened at F.P.bushing contact point.

Any thoughts,? Jim

 

[Onward Allusion]

I've experienced that but not to the degree you are describing. Mine smoothed out after a few hundred rounds. Sounds like tolerances are way too tight and are out of spec. Time to ship it back to the factory.

 

[Jim K]

The solution may be simple. Try firing it with normal ammo. I won't go into a lot of detail, but firing with primers only will usually lock up a revolver.

Jim

 

[ArchAngelCD]

The solution may be simple. Try firing it with normal ammo. I won't go into a lot of detail, but firing with primers only will usually lock up a revolver.

Jim

That is exactly what I was thinking. It's the primer only that's causing the problem.

Why did you shoot primed brass with no load?

 

[popeye]

"Why did you shoot primed brass with no load?"

I wanted to make some snap caps out of factory ammo. I know they'ed only be good for a couple "snaps"

 

[MrBorland]

What Jim K said.

When you fire a normal round, pressure in the primer pocket unseats the primer a bit, while the pressure in the case sends the whole case back into the recoil shield to re-seat the primers. Without a bullet, or, say, with a rubber training bullet & no powder, there's not enough pressure to send the case back, so the primer remains unseated, resulting in a tied up revolver.

Cases used for primer-only shooting have the flash hole drilled a bit bigger to relieve the pressure in the primer pocket.

If you really want/need to shoot primer-only rounds for some reason, look into some Speer plastic cases.

 

[MikeJackmin]

Try it with unprimed brass. If it's OK you don't have a problem, but if the issue persists, then you do.

 

[MrBorland]

I wanted to make some snap caps out of factory ammo

Just get some A-zooms.

 

[marb4]

Had this issue with a Taurus revolver once. Shot loaded ammo and it worked perfectly. I found that the primer alone would allow it to deform. When a live round is fired, the force of the shot causes the brass to "flatten"/reseat the primer.

 

[popeye]

Well..Thanks to all for advice, info, and suggestions. I will buy some A Zooms. I will try the gun at the range. I matched this gun against a friends mod 37 and there's more clearance for the case head on his than mine between the cyl. end and recoil shield. So I thought there was a problem. That could be because his has FP in the hammer and mine hath the FP in frame.

Thankyou all, Jim

 

[RunninLate]

Primers will back out if shooting just a primer causing the cylinder to lock up.

Buy you some snap-caps.

 

[walter o]

with all of the scenarios on using loaded rounds ,what pushes the fired brass and primer away from the protruding firing pin bushing? and the primers were locktited in the case.

 

[Jim K]

Hi, Walter O,

I am not sure I understand the question. Why or when would primers be Loctited into the case?

Jim

 

[ADKWOODSMAN]

It's just one of those things a reloader finds out!!

 

[walter o]

the primers were locktited to see if that would stop the fired primed brass from binding the cylinder . the primers did not move out of the brass ,but the gun was still bound up with the primers locked back into the convex F.P. bushing . I was always under the impression that the breach face must be flat for the fired cases to allow rotation of the cyl..I think most are missing the point that the F.P.bushing is not flush with the recoil shield and is domed shaped

 

[Jim K]

The new FP bushings are indeed domed and a tiny bit proud of the recoil shield, but the old ones were flat and primed cases would also hang up the gun.

Jim

 

[rcmodel]

Doesn't matter.
And Locktight will not reliably hold a primer in a case.

Primer pocket pressure is in the thousands of PSI range, and without a bullet, there is no case pressure to slip the case back in the chamber and re-seat them.

If you insist on firing primers with no bullets, or wax bullets, or hot glue bullets?

You Must drill the flash holes out to 1/8" to relieve the primer pocket pressure and prevent the primers from backing out in the first place!

rc

 

[CZ9shooter]

I ran into a similar issue once too while trying to test for reliability after altering springs. Took me a few minutes to figure out what was going on. Turns out revolvers just plain hate it when you try firing just a primer. Nothing wrong with the gun.