Model 10 .357 conversion


August 2, 2011, 10:28 PM
I have an older Model 10 police trade-in that is in rough shape that I was thinking about doing some sort of customization to. I read somewhere that S&W made a limited run of the Model 10-6 in .357 before releasing the Model 13. That got me wondering if it would be possible to have a smith convert a standard model 10-6 .38 into a .357 (either by replacing the cylinder with that of a model 13 (assuming they share the same dimensions) or by boring out the cylinder on a Model 10.

No need to debate the whys or whether or not the K frame is suitable for .357., blah blah... Just wondering if it could be done.

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Lucky Derby
August 2, 2011, 10:51 PM
Yes it can be done. I wouldn't do it. Yes the K frame can be fine with .357 magnum. However factory .357 K frames are heat treated differently than .38 K frames. I would bet even those M10-6s that were factory chambered in .357 got the .357 heat treatment.

August 2, 2011, 11:29 PM
I am not aware of any differences in the frames. Not saying it isn't true, only that the way I heard it the cylinders are tempered for Magnums, not the frames.

But even just swapping a cylinder really makes no sense. Just buy the gun you want.

Old Fuff
August 2, 2011, 11:55 PM
All K frames are identical, but cylinders are different, both in terms of material and heat treating.

In theory you could switch cylinders, and modify the barrel, but if the job was done right you'd spend more money then if you sold the .38 and bought a .357. Because of that, and some other reasons, such a conversion is not recommended.

August 3, 2011, 02:20 AM
I'm sure you could have it customized for your desired conversion, but it is going to be expensive and rather unnecessary considering how many great .357's are on the market.
I have a thing for K frames even though they have been criticized to death. If you want a S&W that isn't going to break the bank, looks great, and will handle the .357 mag. loads without question find a model 66 or 19. Despite the controversy that surrounds those K frames, I have put thousands of full house hand loaded magnums, mostly the 125 gr. JHP's, through mine and they are still as tight and accurate as the day I bought them.

Doubting Thomas
August 4, 2011, 12:35 AM
Don't. Not only is the gun not suited to it, but you would spend a LOT more trying to get the job done than it would cost to just buy a proper .357 in the first place. Most sane gunsmiths wouldn't even want close to it (liability) and the any future buyers would probably flee from such a conversion.

That old .38 Special, if it's otherwise OK, will probably serve you very well just as it is. I used to sneer at them but the truth is that it's a good round and sufficient for 99% of everything that normal people will ever need to do. That won't sell many guns, but it is the cruel truth.

August 4, 2011, 01:12 PM
Don't.+ 1,000!

Bad Bad idea, all the way around.

We got people here who worry about shooting a steady diet of .38 Spl +P in older Model 10's!!

Heres more on doing a .38 to .357 conversion.


Monster Zero
August 4, 2011, 05:43 PM
Thanks. Keep the model 10 and also run out and buy a .357, then have both. That would be my advice.

Jim K
August 4, 2011, 06:05 PM
I can't state it as gospel, but I heard S&W stretched frames and blew cylinders in developing the Model 19. I would not convert any .38 Special revolver to .357 Magnum. Using such a gun oneself is one thing, but if a gunsmith did it, or if the owner ever sold the gun, court time could be in his future, and I don't mean a basketball court.


August 4, 2011, 06:19 PM
Don't do it. If you want to find out what would happen without the expense, simply load the .38 Special to .38/44 HV levels. The is a reason why the .38/44 HV was recommended for heavy frame revolvers and why they lengthened the case when they created the .357 Magnum.
Convert your revolver to .357 and you'll find out the reason.

Fat Boy
August 4, 2011, 08:48 PM
This question brought back memories from 1977- I heard all kinds of ideas along these lines. At least one "old-timer" told me a guy could take a pocketknife and cut off a bit of the 357 mag. slug (must have been lead, round nose?) and load them into a model 10 and fire away.

Other "experts" insisted there was no reason a model 10 couldn't be converted to fire the 357 mag...

interesting stuff but I would add my vote to what has already been stated..."don't"- there are lots of good .357 mag revolvers out there-

Red Cent
August 5, 2011, 06:38 PM

August 5, 2011, 06:42 PM
Just get a model 13, 66, 19, or a Ruger GP100 or -six series. I've got an old M&P in my safe right next to my 3" model 13. K frames are sweet, you need another one! :D

August 6, 2011, 01:29 AM
It was a common mod back in the 70's. When I was issued my first Model 10, the assistant chief told me to take it to the gunsmith and have it reamed to .357. I carried it for 10 years and bought it when we went to the Model 65. No problems. I also had a Model 64 Pencil Barrel re-chambered and never had any problems with it (except it kicked like a mule).

With nice old Smiths no longer being made I wouldn't do it today, but back then there was a never ending supply of 'em. Who knew?

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