S&W: J vs. K

[Seven For Sure]

I keep reading how the L frames were made because K frames had a hard time staying together with repeated 357 magnum use. Why can a J frame handle the abuse any better, or can they? I just got a 5" 60 and I'd like to shoot it regularly with 357 magnum only. Not super hot stuff but 158's at between 1100 and 1300 fps. I have one K frame and it's a 648 so I'd like to hear from the old Smith guys. Can my new 60 handle alot of 357's and can the old 357 K frames really not?

 

[GrantCunningham]

I think you'll find the difference is one of frequency. The "K" frames were typically holster and duty guns, and as such tended to be fired with full power ammunition fairly frequently. This was especially true as the old habit of training with Specials and carrying Magnums gave way to training with the ammo that was actually carried. As that happened, the problems with the 125gn Magnum loads in the "K" frames began to crop up.

The "J" frames, on the other hand, are likely to be shot very little in comparison, particularly with Magnum ammunition. They aren't at all pleasant to shoot, and that fact tends to keep their round counts fairly low. If you were to shoot a "J" with the frequency that a lot of "K" frame owners did, using full house Magnum ammo, I suspect you'd find durability problems as well.

Then again, who's willing to do that? Not me, brother!

 

[Starter52]

In my opinion, S&W made a mistake when they chambered the J-frame for .357 magnums. Like Grant says, these guns will rarely get fired with a .357 load, but really..... a good +p .38 is all the little J-frame should have to handle.

 

[Majic]

When the K-frame was modified to accept the .357 magnum cartridge the bottom of the forcing cone had to be millled flat to allow room to close the crane/cylinder assembly. This created the weak point of the K-frame magnum.
The J Magnum frame has a full round diameter forcing cone that has the strength to withstand hte magnum punishment.

 

[VA27]

I have a 5" 60, too. I haven't shot any 125s through it, I shoot 158gr GoldDots and 170gr Gold Dots. I also like the Federal 180gr CastCore. It's a lot more pleasant to shoot than the short barreled 60's or the airweight L-frames. If it breaks, Smith will fix it. Shoot and enjoy!

As for the K frame thing, over the last thirty years I've been issued two K frames and one L frame. I bought the M10HB (I had it rechambered to 357 the day after it was issued to me) when we went to the M65. I passed on the M65 when we went to the L frame(didn't have the money).

Never had a problem with either of the K frames, but I shot the L frame loose and had to have the armorer rebuild it 3 times! The last time he worked on it he told me if it shot loose again, it'd have to go back to the factory for a rebuild! When we went to the Glock 22, I passed on the L frame, simply because I didn't want to have to pay to have it rebuilt by Smith.

The problem with the K frame comes on high round-count guns using the 125gr load. The forcing cone can crack where it is the thinnest (the clearance cut for the crane, on the bottom of the barrel). The J frame guns don't have this cut and the forcing cone is better supported by the frame, so that problem goes away. The L frame, with its larger cylinder (more rotational mass) will shoot loose with lots of fast double action shooting (police training and qualification). You pays your money and takes your choice.

We fielded over a hundred K frames during those years and never had any catastropic failures with them. Unless you're shooting thousands of rounds a year through the K frame, I wouldn't worry about it.

 

[Croyance]

Some of the 19-5's had cracked forcing cones from repeated use of full power 125 grain .357 Magnums. Insufficient cleaning may have something to do with this.
There aren't confirmed problems with the rest. A lot of heavy loads may necessitate timing work, but I've been able to find K-frames that have taken decades of hunting loads and held up.

 

[GRIZ22]

You will develop problems with using magnums in a J frame over a period of time. I doubt you are actually getting 1300 fps in a J frame w/ 2" barrel. If you are that is a hot load. Have you ever given any thought to a +P+ or +P load? You are not really giving up a lot (100-150fps) and it's not only easier on the gun but easier on you as well. I've chronogarphed Federal 147 +P+ out of a 640 at 980 fps. The little bit of difference makes controlability a lot easier.

 

[Seven For Sure]

Thanks for the responses. I'm getting 1300 or more due to the 5" barrel on it. I actually have some DT 180 hard cast that do 1300 out of a 4" but I had no intentions of firing those from my 60. I'll save the Double Tap and Buffalo Bore for my 686 though. The Blazer claims 1150 from a 4" tube and the Georgia-Arms I have do 1200 and 1250 from a 4" tube. It's a nice little gun and I don't want to beat it up. Those medium 158's are plenty for smaller varmints and long distance plinking. I fired a cylinder full of super hot 125's and decided I won't be shooting those anymore.