cylinder exchange 640 (no dash .38) to new .357 cylinder

[Shotgunner]

Are the dimensions of both guns the same?

Can I exchange the cylinder on an older Smith and Wesson model 640 .38 cal, to a new 640 .357. Both the new and the old gun are all steel construction.

Magnum ammo will not fit into the older cylinder because of a belt at the bottom of the .357 cartridge. But an eyeball measurement suggests that the old cylinder would accommodate the length of the longer .357 ammo.


Will the cylinder physically fit into the frame of the old gun?

Is the old gun strong enough to handle .357 ammo with the new cylinder?

Is this simply a bad idea on the basic premise that the old revolver wasn't tested or rated for this pressure level of ammo?

I have a 6" 686 and a python that are both in great shape. So I can safely fire .357s. I am inquiring just to see if the idea is feasible.

Edited to add: the gun was originally bought in 1992.

[MCPreacher]

I don't think that the old frame and barrel are rated for anything close to modern cartridge .357 mag, neither is the cylinder. Advances in powders, steel and machining make the new pistols a lot tougher than the old ones.

I imagine you might get away with it for a few rounds, maybe even a few cylinders, but sooner or later, that swap is bound to cause trouble.

[Berto]

I wouldn't.

I believe the frame window is longer on the 'improved' J frames for the longer .357 cylinder.

[LSP972]

Don't even THINK about it. As Berto stated, the frame window in the .357s is larger, just to discourage such parts-swapping.

You could put a .38 cylinder into a .357 frame, but then you'd have a large flash gap that would cause another set of problems. Those can be solved by setting the barrel back, but you're talking major sugery there.

If you want to experience the thrill of .357 recoil in a J frame package, I can save you some time and money.

Get a good, solid metal head hammer of at least two pounds weight, place your shooting hand flat on a hard surface, and strike it with the hammer until the thrill is gone... ;)

.

[Shotgunner]

I knew there was a reason that I have been reading this board for the last five years. You can't pay for advice like this. Enough said, I'll stick to my 686.

Don't even THINK about it. As Berto stated, the frame window in the .357s is larger, just to discourage such parts-swapping.

You could put a .38 cylinder into a .357 frame, but then you'd have a large flash gap that would cause another set of problems. Those can be solved by setting the barrel back, but you're talking major sugery there.

If you want to experience the thrill of .357 recoil in a J frame package, I can save you some time and money.

Get a good, solid metal head hammer of at least two pounds weight, place your shooting hand flat on a hard surface, and strike it with the hammer until the thrill is gone... ;)

.

[gunsmoke92]

Good plan. That would be a BAD thing, besides, .38s are a little more pleasant to shoot in the J frame. The 686 is the real deal if you're into the .357. :supergrin: