J "magnum" frames...what are they?

farandfine · May 11, 2021

Hello everybody, I was looking through my copy of the
Standard catalog of Smith & Wesson, and ran into a puzzling statement. It is stated (page 246) that the model 37-3 changed to the J magnum frame and hence, the possible use of +P ammunition. I don't know what a magnum J frame is (but it's easy enough to guess), and wonder how it differs from an older J frame in dimensions. Can anyone please tell me?

Also, I'm wondering about my own 37-2 which has ".38 S&W SPL +P" stamped on the left side of the barrel. A mistake? It's my impression that with all the guns S&W made there are bound to be overlaps and anomalies. But, any other explanations?

Thanks, John

BLUEDOT37 · May 11, 2021

In checking the dimension differences, with a digital caliper, between my late model M638 (Al, 38 Spcl.) and my M340PD & M360 (Al/Sc, 357Mags), the only substantial one I found is the top strap is thicker on the 357 Magnums.

.

murphydog · May 11, 2021

The key visible feature to the J Magnum frame is the integral frame lug, the J shaped, left sided frame protrusion that (almost always) keeps the cylinder from sliding off the back of the gun with the action open and muzzle up. In earlier guns the lug was a separate part.

Their dimensions are different in other ways from earlier guns and someone here probably knows where.

There were a few pre-J Magnum models factory rated for .38 +P, but none for .357.

s&wchad · May 11, 2021

The change to the J Magnum frame occurred when S&W went to CNC manufacturing. The most obvious trait of the J Magnum frame is the integral frame lug/ledge (top gun in photo), that replaced the old style pressed-in lug (bottom gun).

The J Magnum has a frame window that’s 1.73” long. The previous style had a frame window that was 1.64” long. They stretched it to accommodate factory .357 Magnum cartridges, but standardized on the new size across the board. Even guns like the 317 (.22 LR) have the longer frame window. S&W didn’t make the frame section under the barrel any thicker on the J Mag and that’s typically where these alloy frame guns fail.

Steel frame guns and aluminum alloy frames containing scandium can handle .357’s, but not all aluminum J Mag frames contain scandium. I think the statement you quoted about +P ammo is a bit misleading. Any .38 Special J mag framed gun can handle +P ammo, but so can just about any other J frame (with the exception of some of the early Airweights with aluminum cylinders, which shouldn’t be shot at all). S&W did mark some old style pre-J mag alloy frames as suitable for +P and it wasn’t a mistake. I assume it was done to meet some contract spec’s or as a marketing tool. A steady diet of +P’s will probably cause premature wear and shorten the service life of the gun, but it’s not going to blow it up.

The whole +P thing is highly overhyped in my opinion. Some older factory loads were hotter than todays +P’s. I don’t make a habit out of constantly shooting the hottest loads available out of my older alloy J frames, but i don’t do that with any of my guns. The most common failure on S&W alloy revolver frames is the dreaded crack under the barrel, but there doesn’t seem to be any connection with shooting +P’s. Some frames just cracked while sitting in the box.

two-bit cowboy · May 11, 2021

The J-frame models that evolved from the original Chiefs Special series (carbon steel 36 and aluminum alloy 37) were never made to accommodate .357 Magnum ammo.

The J-frame models that are .357 capable are the stainless steel variations (i.e., Model 60). The first ones were the Model 60-9 with a 2⅛" full lug barrel and Model 60-10 with a 3" heavy barrel and target sights.

S&W launched the J-magnum frame in 1996. Since then, actually since 2001, the company has produced many non-carbon steel J-frame models that accept the magnum ammo.

cmansguns · May 11, 2021

some barrels were marked +P

My first EDC was a Model 36 in 1971. Since then I've always carried J Frame 38 Special, so upgraded to Model 60 (no dash) for the stainless feature, then listening to the +P hype at the time, "upgraded" again in 2002 to a lighter weight Model 637-2.

None of the guns, including the Model 36-1 (blue or nickle) will chamber a 357 round.

The 637-2 does have the barrel marked for +P whereas the others are simply roll stamped 38 S&W Special Ctg.

My normal EDC load was factory brand 38 Special, but when I got the 637-2 my EDC load is now Speer Gold Dot 135 gr. JHP, and my normal practice ammo is Winchester (T) 130 gr. FMJ

I haven't really ever noticed and different perceived recoil from any of the 38's shown, but sure can tell with 357 Magnum out of my Model 66, 27-2, pre-27

Minorcan · May 11, 2021

Great info. My M-60 in 357 has the integral frame lug and it is strong. I was shooting Winchester white box and one of the rounds had way too much powder. What a kick and fire shot out six feet and bunches of fire from around the forcing cone. It burned the hair off my hand. Scared the bejeezers out of me. I unloaded the gun and inspected it when I got home. No damage, I was impressed.

farandfine · May 12, 2021

Thanks everybody!

Hello everybody. What a lot of really good information...THANK YOU! And it's interesting and amusing to think that my 317 is on a "magnum" frame!

I'm like many of you. Firing +p ammo, even from a K frame model 19, is not much fun for me. My whole interest in this is my old academic's curiosity.

Cheers,
John

J "magnum" frames...what are they?

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