Been trying to find a 38 Super that I like, but just dont find any. So I decided to convert one of my 357. Need help deciding...
Model 66 2.5 inch 6 shot...
Model 686 4 inch Mountain Gun 6 shot...
I realize it depends on the use, but I am thinking general overall use.
Your thoughts would be appreciated.

FYI only, not saying its the best idea in the world, but I shoot .38 Super out of my 586 all the time. It is an unmodified .357. The Super headspaces on its semi-rim. Long jump to the rifling, but it is fun to play with.

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Would you be planning to change out both the cylinder and the barrel? Seems to me that would be the way to go as the bore of the Super is a couple thousandths smaller than .357. I'd probably tilt toward a 4" barrel if you'd be going to use it for an all around general purpose gun.

Having said all of the above, it sounds like an expensive project to end up with something not as good as the original gun in .357, but I realize we gun-nuts do like to fiddle!

MTKTM, I was looking at Pinnacle site and it seemed they just did the cylinder. But you asked the question that I have been wondering about. 355 vs 357 and how could you use the same barrel? I am calling them Monday and see what it is that I just do not understand. Thank you very much for your reply.

I would get a extra cylinder for the 686 and have it fitted and turned into a 9mm/38super. I have one and love it.

Does the barrel diameter being different effect the new cylinder?

People make waaaaayyy more of that two thousands of an inch than it deserves. I have a 360J that was rechambered to 9X23 by Pinnacle, I have seen no appreciable change in accuracy vs .38spl ammo and I've shot 9mm, .38 Super, and 9x23 out of it. There are several other forum members that have rechambered guns with similar results.

I would follow LC '92's advice and try some .38 Super in your gun as it is. My 586 L-Comp also chambers and fires .38 Super just fine. If they work in your gun, your all set. No sense in wasting your money.

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As others have pointed out, I'm possibly making too much of the bore diameter issue. It's a lot like having a 22 Magnum cylinder for a 22LR gun, it works even though the diameter is a couple thousandths off and the twist is different. I guess my thinking is that if I have a gun solely dedicated to shooting a given cartridge, I want it to be appropriately barreled and chambered. But it sounds like the folks at Pinnacle have a lot of experience with such conversions, so I'm sure they can guide you far better than I can.

I believe .38 Super actually uses .356 bullets, not .355

This is why I have enjoyed a confusing/rewarding life long interest in loading and shooting... My Hodgdon Data Manual states .355. My Lyman Manual states .355. My Hornady Manual states .355 to .357. The primary bullets I use are .356. My entire life has been trained to believe in numbers or bad things happen. Reloading/Shooting is at times a real pain in the ***, when each manufacture lists their recipe and they vary so widely. I imagine it has something to do with lawyers that are involved in just about everything these days. I really appreciate everyones helpful input.

No conversion necessary. Your modern S&W .357 will chamber and shoot Winchester and Magtech .38 Super ammo just the way it is. Other brands of factory ammo will not work.

Stiab, sounds good to me. What indicates that Winchester is good and other brands are bad. Thought factory ammo was built to specs. by all manufactures. I have mostly hand loads and they fit perfectly in the cylinder holes of all my Smith 357s. Just curious. Thanks

Uh oh, and when you have a lawyer who is also a handloader, things can get hairy real quick!!!

One of the things I discovered about 15 years back when I got a chronograph and began measuring velocities of different loads was that, almost invariably, I was finding velocities were a fair bit less for a given load than the manual might claim. Never more, always less. And according to the manual these were tested out of real guns, not special minimum pressure barrels/chambers. I could see it if it was an isolated incident, but that was not the case, it was across-the-board and repeated over and over and over again. At the time I was mostly interested in handgun loads and was competing in USPSA/IPSC matches where velocity mattered in the context of power-factor and scoring. I found that a load that should easily make "major" according to the manuals would not even come very close! I then, out of curiosity, began checking some rifle loads and data over the chrony and same results.

Nowadays I'm not seriously competing anymore so it makes less of a difference, but it always bothered me that the data was so far off so consistently. Why not simply be honest about it rather than trying to protect us from ourselves????

Thought I would dig this up again. I have a 66 and none of the 38 Supers fit. An 8 shot 627 4 drop right in and 4 not. New 686 Mountain Gun they all drop right in like it was made for them. The point I guess is I am surprised by the wide variations in cylinder holes. Stupid me I thought they would all be like the Mountain Gun and be somewhat consistant. Oh well I keep learning.

Not to offend anyone but what is the point of this? Other than saying you had done it I see no advantage what so ever.

Dave

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I guess if you had a whole pile of .38 Super ammo, there might be some purpose to it. Otherwise, the .357 Mag and .38 Special cartridges have that velocity range and bullet sizes pretty well covered.

I guess I should have been more clear...I have a couple thousand 38 Supers from my many Colt I previously owned. I have been trying to replace them and find nothing to meet my needs. Sooo I thought it would be a Hoot to shoot some, while still trying to find a Colt. Top Gun Supply had 2 of them but by time I called they were already spoken for. I the process I learned that the cylinder holes in the new S&Ws vary widely.

I have found that the case as well. They drop into my M60, push into my M14, & don't fit in my 586....or was it the other way around. But they didn't fit in either Colt revo. I have.

I had about 300 rds of super, & sold the gun. My .38 super were loaded with .357 135gr jrn.

I've thought about this a lot.

The .357 bore (grooves), has a land diameter of about .350.

A .355, or .357 diameter bullet gets a LOT of material squeezed somewhere, much of it radially, so this isn't as bad as it sounds.

Is this just whacky thinking, or what?

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When in doubt, pick up a 627 in 38 Super.
You'll be glad you did.

Bob

Bob, where would I find one???

There was a new run of them last year. There should be some on Gunbroker etc.

Bob

Just to keep beating this subject...I found a report by Ed Sanow who conducted an extensive review of this subject and yes you can do this. His comment was interesting to me that instead of using 38+P in a 357 you can use the 38 Super and get much more power, less muzzle flash, and better accuracy. Sound like what I will try out in my 66 and 386 NightGuard when it gets here.