S&W 15-3 With .357 Chambers


sweet betsys ike
January 4, 2014, 10:28 PM
Hi I have a model 15-3 serial #8K597** and it will chamber .357 magnum rounds. Every type of factory and hand loaded ammo I have tried drops right in flush with the cylinder. and the cylinder shuts with no problem. I found this out showing a novice shooter how .357 magnums are not suppose to chamber in .38 Specials .[ NEVER ASSUME ANYTHING ] And they don't in any other of the .38's I own. This was a cops back up gun 25+ years ago, But He is Gone now so I can't ask him about it. I wonder if he had it bored out to except magnums. or if it was a factor error or what. Anybody see this before ?

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January 4, 2014, 10:57 PM
It would only take a few minutes to rechamber to 357. Sounds like at some point somebody did.

January 4, 2014, 11:14 PM
I own a 15-4 whose chambers have a constriction about 1/4 to 3/8 inch from the barrel. This constriction prohibits the loading of .357 length cases.
Maybe this is what is referred to the gas ring?

January 7, 2014, 05:44 PM
Prospector, that 'constriction' is the end of the chamber proper. The smaller diameter area forward is the 'throat' (at least from where I hail, possibly other terms in other parts of the world). That is NOT the gas ring. That is what keeps .357 Magnum ammunition from being chambered. At least when everything works correctly.

If one measures that forward shoulder, the measurement should match up with the length of an empty case from the cartridge in question (in your instance, a .38 Special).

The gas ring is a very short 'tube' arrangement on the front of the cylinder, surrounding the extractor rod. The purpose was to keep the burnt powder gases from firing from entering the fissure between the extractor rod and the cylinder itself. The burnt gas is usually full of fine grit and accelerates wear.

IKE, I'd believe someone rechambered that revolver for .357 Magnum at some point. It was more common with stainless steel revolvers, but not unknown in the blue steel guns. Quite often, they would not accept some of the heavier bullet loads as the bullet would project out the front of the chamber.

I'm pretty adventurous at times, but I don't believe I'd run much .357 Magnum ammo through that revolver. In fact, I would look the cylinder over with a magnifying glass (after a good cleaning) looking for tiny cracks or other evidence of impending failure prior to shooting it.

Old Fuff
January 7, 2014, 06:14 PM
Yes, some have been known to rechamber this-or-that .38 Special into .357 Magnum. I even know of an instance where a Colt Detective Special was rechambered, with far from good consequences.

What those that did (or still do) this don't know is that most manufacturers use different steel and heat treating procedures in magnum cylinders.

If someone comes across an rechambered .38 Special I strongly suggest that they let someone else buy it.

Jim K
January 7, 2014, 10:05 PM
Amen, Fuff. Some cops who were restricted to .38 Special revolvers wanted to use .357 as a carry load, hence the alteration. The guns usually stayed in one piece, but the practice is NOT recommended.


January 9, 2014, 01:52 AM
Not that I would do it, but I was under the impression that that was safe to do specifically on the service/security six series. Designed and originally chambered for the .357, some were chambered .38 for various reasons.

I got that impression from Ruger who told me that those .38 cylynders were exactly the same as the .357 cylinders and perfectly safe to rechamber.

I lost a $50.00 bet on this. I wouldn't recommend this on any other .38 but apparently its ok for those two particular models.

Please don't hate on me. Just relaying the facts.

RCMODEL.... care to weigh in??

January 9, 2014, 07:05 AM
Thanks Archie! I was looking for an explanation like that.

Ron James
January 9, 2014, 08:24 AM
And it could be nothing more than someone wanting to shoot .357 wad cutters in their Model 15. Less bullet jump for accuracy or so I've been told.

sweet betsys ike
January 9, 2014, 09:25 PM
Thanks to all that replied,[ Especially Archie ] . I think he may of had this done. I do remember he used a model 19, 4 inch as his main carry gun. The 15 is a snub nose, and was a back up. I guess if you are in a fire fight and your main weapon go's down or whatever, then you will still be able to use what is in your belt. after you fire the first 6. I'll be sure to keep all .357 ammo away from it! [BETTER SAFE THAN SORRY!] I just wondered if there is a difference in the length of the cylinder between the .38 and .357 on K frame revolvers and maybe the factory installed the wrong one?

Old Fuff
January 10, 2014, 12:54 AM
Yes, the .357 cylinder is longer (1.56" = .38 /1.67" = .357) so a .357 cylinder won't go into a K-frame that been fitted with a .38 Special barrel. I highly doubt that S&W made any mistakes.

January 13, 2014, 05:23 PM
Down here in Southern Peru officially magnums were banned before we arrived in 86. Several Model 10 S&W's were modified to chamber caliber .357 ammo that was technicly reserved for police use. Have not heard of any blowups.. but ammo is expensive here so most firearms are seldom fired by the average individual owner.
In the last 15 years some retiring police have sold off their personal caliber .357's as revolvers are now viewed as "out of fasion". Not everyone holds that opinion :) .
Mike in Peru

January 13, 2014, 06:46 PM
My brother bought a model 36 S&W that had been opened up to 357 He was out shooting and a deputy stopped by to chat, he saw the snub nose and patted his magnum stating " you need a gun like this. He had the 12 bullet slider on his belt and my brother picked one out opened his cylinder placed it in his cylinder and closed it. The deputy made a quick retreat behind his squad car so he wouldn't be hit by flying gun parts as my brother touched it off. The deputy couldn't believe it. It actually survived. I might add my brother was on the Sheriffs Boat Patrol and he bought it as a backup to his Model 19 for ammo interchangeability

Old Fuff
January 13, 2014, 09:20 PM
Understand that S&W .38 Special cylinders were not made of the same steel and put through the same heat treating process that .357 Magnum cylinders were. A few magnum cartridges might not blow up a gun, but would expand a chamber(s). Once one or more were expanded the cylinder was over stressed and ruined. Continued shooting might well result in a cracked or ruptured cylinder wall.

As is so often said, there isnít any cure for stupid.

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