I wonder if I could turn my .38 special Model 64 into a .357 just by installing a Model 66 or 686 cylinder?

I have several guns of each caliber so this is not something I need to do, but the question is: "Would it be a safe conversion"?

What about reaming the . 38 special chambers to .357 depth?

Has anyone actually tried it himself?

__________________
NRA Life Member

I wonder if I could turn my .38 special Model 64 into a .357 just by installing a Model 66 or 686 cylinder?

I have several guns of each caliber so this is not something I need to do, but the question is: "Would it be a safe conversion"?

What about reaming the . 38 special chambers to .357 depth?

Has anyone actually tried it himself?

__________________
NRA Life Member

A direct swap-out of a K frame magnum cylinder for a non-magnum one would not work because the .38 Special cylinder is shorter than the magnum cylinder, and would leave the b-c gap at some unacceptable 0.150" or so.

Reaming out a .38 Special cylinder to .357 Magnum is an old idea sometimes tried by "bubba" type gunsmiths, and is a poor idea. The amatuer reaming seldom leaves an acceptable chamber finish, and the end product is unsatisfactory: a gun capable of firing magnum pressure ammunition that was only designed for half the chamber pressures. There may or may not be heat treat differences between a .38 Spl frame and a .357 frame, but who wants to find out if it will hold up? Not me.

In my 30-something years of gunsmithing, I've encountered a few converted guns. In latter production N frames, the conversion did not seem to cause any problems (Outdoorsman and Heavy Duty models), but in K frames (M&P and Combat Masterpiece models), rough reamed and bulged chambers were fairly common. It is not a recommended practice, since factory .357 guns are readily available.

It isn't even safe to swap cylinders on same model guns. They extractor stars are fitted to the hands and frame.

The frames of .38s and .357s don't necessarily use the same metal and definately are heat treated differently.

The model 15 frame wasn't interchangable with the model 19 frame. Could you get away with it short term? Possibly, wouldn't trust anyone to do the work who was willing to do it.

Thanks to all for your input and time. I appreciate your thoughts.

__________________
NRA Life Member

Actually, depending on period of manufacture you are wrong, or not completely right, on both counts.

In 1974 I attended the S&W Armorers School as a police armorer. I was there for automatics, and since they did not teach automatics in the armorers school at that time was assigned to the automatic section directly under the automatic foreman. To learn the guns spent two weeks doing range repairs of guns that didn't pass the test firing. (Just background)

While there I asked a very specific question about just this subject which was basically "Between .38 Special guns and .357 Magnum guns is there any difference in either material or heat treatment?" The answer was NO, they are identical. Think about it, why would you want to stock two different alloys which require different heat treatment? This increases costs beyond the savings from one alloy possibly being somewhat less expensive than the other, and the risk of mixing up parts of different materials? It is less expensive from a production standpoint to use the same material and heat treatment for all guns and have some much stronger than necessary.

On the second point, the only difference between the normal KT frame for the 14, 15, 16, etc, and the frame which is specific to the 19 is a very slight difference in the contour of the front of the frame to match properly with the extractor shroud. It isn't thicker, wider, or different in any dimension except for this point, and this is purely cosmetic. Both the 15 and 19 frames, at least at the time the question was asked had identical material, heat treatment, and for anything affecting strength were of identical dimensions.

Is re-chambering a model 10, 15, 14, etc. from .38 Spl. to .357 Magnum a good idea? Not really, for several reasons, but strength isn't one of them.

Believe me or not, I really don't care, but don't argue I am wrong unless you have a better source of information than "It just sounds right to me".

ALK8944- thanks for the updated information. My info was applicable to much earlier production..and from a source I thought trustworthy. It may well be that by 1974 product mix/demand had made single alloys/heat treat a production necessity.

In them thar days I'd seen one model 15 that'd been "magnumized" and was markedly unimpressed. Thinking back on it, I'm not sure if the result was due to workmanship, materials or handloading.

I agree completely, I also attended Armorers school and was told the same thing. Working for a large department with many old revolvers, I have on occasion replaced both the barrel and cylinder on frames and converted them from one to the other. (yes I have converted a 357 to 38 because of a bulged barrel and I had the parts on hand) If you think about it, A model 64, 65 and 66 use the same basic frame, Just different barrels, cylinders and sights. I also agree, that in most cases, just trade what you have for what you want. Just my 2 cents.

If the material & heat treat on a M. 64 is the same as the M 65 & 66, I suppose there would be no reason a 38 special couldn't be safe at, say, 25000 psi?? Additionally since the internals are the same as those used on the .357, I suppose there would be no premature "wearing out" a .38 special with these heavier loads.

This isn't about "hotrodding" a .38, or turning it into a magnum. It's about the GIANT safety factor built into modern S&W and Ruger revolvers.

On the Shooting USA show they took a S&W (L frame).357 revolver and plugged the barrel with 3-4 bullets loaded light so they didn't exit the barrel, then they fired a full-house .357 load into the plugged barrel. The only damage was a "ringed" barrel where the .357 hit the barrel obstruction. The cylinder and everything else was undamaged.

__________________
NRA Life Member

Plus 3 for comments by Alk8944 and topsaddle. I spent two weeks at the factory in 1979 and agree with everything they said. I saw frames coming out of the molds and dumped into barrels. The steel that was poured into the molds came from the same pots. Model designations come much later in the process. My time was building model 64's and repair of many other K frames. There were actually some 64's chambered in 357 before the 65 was born. As far as the autos of that era - we only spent 2 days identifying issues and replacing parts. Not much smithing went into them. Even the instructors did not like the 39's and 59's.

__________________
S&W factory revolver armorer

Riddle me this....Would/could you convert a 4" standard (i.e. pencil/skinny) barrel M64 to .357? Would that barrel hold up to .357 pressures? Not that I would mind you, just curious. I always that that gun would be the felines rear.

My (.44 mag.) 629 Mountain gun barrel has a .094 inch wall thinkness at the muzzle. My (.357) Model 28 S&W has a .125" wall thickness at the muzzle. They didn't explode yet.

Nonetheless, I wouldn't convert my .38s to .357. I'd spend my time and energy finding a safe .38 load that would give me about 1100 fps with a 158 grain bullet.

__________________
NRA Life Member

Regarding the inputs from ken158; Topsaddle, and Alk8944, am I correct in concluding that there is no real advantage in a .357 Magnum loading than a .38 Special?

It seems that the .10" increase in cartridge case length, and subsequent increase in gunpowder, has been largely negated through technology and better gunpowders. I remember people saying there was no real difference between the .38 and the .357 Magnum over 30 years ago, but that the legend behind the .357 Magnum kept it going.

What say you?

Regards,

Dave

.357 mags are longer only to prevent chambering them in guns that can only handle .38 spl pressures. NOT because you need the case volume. You can duplicate .357 mag performance in .38 special cases pretty easily.

Tomacatt51:

Thanks for your response. That was my conclusion, but I appreciate the confirmation. I guess the other plus of having a revolver chambered in .357 is that it will safely chamber any .38, as well as any .357 Magnum offering. The converse is of course, not so.

Regards,

Dave