.38 to .357?

Me239

Member
Joined
Feb 4, 2013
Messages
133
Reaction score
95
Hey, guys! Since talking to some guys at a pawn shop, I became really curious about the conversion of a model 10-6 to .357. Since its a k-frame, converting the model 10 effectively makes it a model 19. The guys said the conversion consisted of taking a .357 cylinder and also shaving some of the forcing cone off to allow the extra length of the .357 cylinders. I'm curious about this because I cannot currently buy a .357 pistol, and converting my K-frame (which is already pretty huge for a snub) would allow me to shoot .357 as well as .38 special out of it, only increasing its function. My question to you guys is what do you guys think of modifying revolvers? Does it take away from the value, or add to it? Does value lie within the originality of the revolver, or in the function it serves? Keep in mind, I'm not able to purchase a .357 at the moment.
 
Register to hide this ad
In my opinion -which is worth what you paid for it- Leave the M-10 alone and shoot +p`s which are close to .357 performance, if that is what you want.
Modifying the m-10 would cost a lot and greatly DECREASE it`s value.
You would be much better off trading off the M-10 and buying a .357 of your liking . The difference in cost will be much less than what you would have put into the conversion, and you haven't ruined a nice M-10 and you`ll have a proper unmolested revolver.
 
Well the problem is I can't buy or trade for a .357 since I'm under 21. I also inherited this revolver, which is my main concern. A .357 would be much better for things like boar. Do you see anytime where such a conversion would be justifiable?
 
Questionable Conversion

It can be done; BUT there are many many .38 Special "K" frames out there that are older and were not subjected to the same high grade of heat treating nor is the steel alloy up to today's standards. When I was gunsmithing, I was amazed at the 'butter soft' quality of steel used by most handgun manufactures in the early days. The much higher pressures of the 357 would immediately start 'battering' those butter soft older "K" frames until it became unsafe to shoot in several ways. One could handload 357 down to near 38S pressures, but what would be the point?

The only 38 to 357 conversion I could 'sort of' support would be to take a modernday Model 67 and change both the barrel and cylinder to 357. The alloy of the 67 frame and its heat treating process is exactly the same as the Model 66. Again, that would be economical only IF one had the parts laying around not being used for anything else. ..........

IMHO, until you can save up the $s to purchase an actual .357 Mag handgun, shoot the heck out of your .38 Special and work on developing the very best stance, handgrip, sight picture, breath control and trigger press you can with the goal of becoming the very best revolver shot possible. You will be much further ahead come the time you do start shooting magnums. .............. Big Cholla
 
Last edited:
You will shoot an old family heirloom loose in no time. Take care of it and buy a .357 when you can.
 
What you are considering doing is basically destroying a model 10 that was passed down to you from, I assume, your grandfather.

Here are a few rude and immutable facts of life.

First, you won't get Magnum performance out of a 2 inch model 10, the barrel is just too short. Sometime back someone in this forum did a comparison of 38 caliber, 38 +P, and 357 Magnums across a chronograph using one of the J frames with a 1 7/8 inch barrel. The results indicated that the best performing load out of this short barrel was Speer's Short Barrel Gold Dot 38 +P. In addition as I remember it the 357 Magnum loads tried only provided 38 +P performance with a lot more flash and post barrel blast.

Second, the K frames have a CRITICAL weakness in regards to the 357 Magnum and this particular weakness is independent of the barrel length. That weakness is the flat on the underside of the barrel inside the frame. Look almost anywhere and you'll find recomendations that the K frame shooting 357 Magnums should only be fed loads featuring a 158 grain or heavier bullet. History has shown that 125 grain 357 Magnum loads tend to crack the forcing cone on a K frame. BTW I believe this is due to the Kinetic Energy carried by the bullet as it exits the CYLINDER. Basically the lighter bullets leave the cylinder fast enough that they can carry enough Kinetic Energy to crack the forcing cone. Most high performance loads tuned for short barrels feature lighter bullets in order go gain as much velocity as is possible out of a short barrel. That Speer ammunition mentioned above features a 125 grain bullet so it's not suitable for a short barrel K frame.

Third, when the forcing cone on a K frame barrel splits it tends to get "opened up" by the user continuing to shoot the revolver. Perhaps just enough to finish off just one box of ammo. When this happens it's about 50-50 whether the frame will crack when that damaged barrel is removed.

Fourth, it's an open question on whether the barrels and frame for the 357 Magnum receive any special heat treating. Depending on the era of manufacture it's quite possible that at some periods the 357 Magnum were treated specially and at other periods all of the 38 caliber revolvers received the heat treating once reserved for just the Magnums. So, nobody can tell you if the barrel and frame on your particular revolver is actually strong enough for the 357 Magnum. BTW, if you ask S&W you will be told that the model 10 is simply rated for +P 38 caliber and nothing more.

Summation is rather simple. First, stop listening to Pawn Shop Commando's, they don't care a whit about what is best for you. All they are doing is creating a potential customer when you blow up your grandfathers gun. Second, a snub nose in any caliber is a miserable choice for defense against an animal that can move as fast as a hog. If you really need something for defense against feral hogs I would suggest that you get yourself a 12 gage shotgun with a 3 inch chamber. That will be a heck of a lot easier to aim at a moving target and packs enough power to discourage the most aggressive boar in the woods.
 
Last edited by a moderator:
How likely is a wild boar attack where you live? I'm 58 and live in/traipse the Louisiana swamp and marsh. On the chance I see a pig (we don't have "boars" here) he's usually doing a 180 from me and opening fast. If I am out looking to actually shoot one, I am hiding waiting for him to come into range at which time I'm gonna shoot him with the biggest thing I got which is NOT a snub nose .357! I would think that loading your .38 with +p's would give you all the firepower you would be able to handle to fend off whatever might decide to charge you. Remember a hit with a .38+P does a LOT more damage than a miss with a .357.
Taking gunsmiting tips from pawn shop commandos is usually a pretty bad idea. These guys sound like a bunch of goobers to me. Besides anyone here knows that the proper way to ruin a .38 by turning it into a .357 is to simply bore out the cylinder charge holes to accept the longer .357 case.:D A lot less work involved and you still get a nice ruined revolver.

I was young once and had calibre envy because my 67 that my dad bought me wasn't a 66 and I suspect that you are now in the same place. Be patient and do not do what I did (sold that 67 and bought a ,357 now long gone). Keep your model 10-6 and get a .357 when the time comes-you will be very glad you did. Trust me on this one-I'm an old fart :D
 
He is not an idiot. He is just young and uneducated in this. He was smart enough to ask questions.
Btw you could get a good idea of heat treatment with a hardness tester. I am sure my little Ames handheld would be able to take readings on a variety of K frames and get some answers in this regard.
I do agree that this conversion is not very feasible, especially for a snubby and shooting 357 or any other magnum in real short barrels only gives a lot of bang and muzzle flash.
Another problem not mentioned in the method of conversion proposed by ME239" adviser is trimming of the forcing cone end of the barrel would result in less opening for the bullet to go into the barrel. Trimming the forcing cone should be done with a special tool that will keep it square and then followed up with another tool that re-cuts the forcing cone.
It is good to think and be curious. It is also a very good idea to ask questions and gather information on thing like this before you beginning.
Me239. Don't worry you will be 21 soon enough. I remember being a minor and thinking that day would never come. Now I look back from 62 and when I see the date posted by the cash register that states when you have to have been born to buy booze and think it wasn't very long ago. LOL
 
Well...I wouldn't be quite so harsh on Me239...:)

It would be an ill-advised conversion for the reasons mentioned above. Several specialty ammunition makers load heavy .38 Specials called +P, which you could try first. If you can use these effectively (meaning within the vital areas of boar as you mentioned, at the distances you intend to hunt, from a field position) you are ahead of the game, so to speak. You mentioned also you have a 10-6, which has a 4" barrel and is technically not a "snub nose" revolver.

Rifles and shotguns may work well against boar, too, and you can own whichever one of these you like. Food for thought.
 
Hey, guys! Since talking to some guys at a pawn shop, I became really curious about the conversion of a model 10-6 to .357. Since its a k-frame, converting the model 10 effectively makes it a model 19. The guys said the conversion consisted of taking a .357 cylinder and also shaving some of the forcing cone off to allow the extra length of the .357 cylinders. I'm curious about this because I cannot currently buy a .357 pistol, and converting my K-frame (which is already pretty huge for a snub) would allow me to shoot .357 as well as .38 special out of it, only increasing its function. My question to you guys is what do you guys think of modifying revolvers? Does it take away from the value, or add to it? Does value lie within the originality of the revolver, or in the function it serves? Keep in mind, I'm not able to purchase a .357 at the moment.

The "guys at the pawn shop" are not operating within the realm of any kind of safe reality, and have been, if you will pardon the expression, "smoking too much crack."

Doing what you suggest will not turn your model 10 into a Model 19. Unless you also change the frame to a KT frame, and the barrel to a .357 Magnum barrel with enclosed ejector.

Just how do these "guys at the pawn shop" think that they are going to "shave some off the forcing cone" to make that .357 cylinder fit? Do you suppose they know the difference between a barrel shank, a forcing cone and a lunette?

Increasing its function? Unlikely. Increasing its ability to cause you serious injury? Maybe.

Modification such as you are considering? A very bad, and potentially unsafe idea. I realize the 10-6 served as the basis for the experimental .357 K frame with fixed sights, which resulted in the introduction of the Model 13, but ordinary 38 Special Model 10-6s may not have had the same heat treat, the barrels may or may not be rifled the same, and there could be other issues. And "shaving some off the forcing cone" is just not the way to do it. In fact, the whole description you give makes it sound like "amateur night out."

Value will be destroyed. Only a complete imbecile would purchase such an abomination if you ever decided to sell it.

If you are unable to purchase a .357 Magnum, then just get some good 38 Special +P defense ammo and consider yourself well armed. .357 Magnum out of a snub is not really going to set the world on fire anyway. If you just have to have heavy stopping power out of your Model 10-6, order up some Buffalo Bore "Outdoorsman" 38 Special ammo. It is the same as the old 38/44 (158 grain Keith type semi-wadcutter at 1125 fps or so), and quite frankly, that is as good as most .357s these days, as manufacturers have been loading down the .357 Magnum for years now. The issue you are trying to solve can be handled with the right ammo for the gun you now own.

In my opinion, you would ruin a perfectly good 10-6 to create something that no person with even the slightest knowledge of Smith & Wesson would ever consider purchasing. Ever. Bad idea. Don't do it.

And, stop paying attention to the "guys at the pawn shop." Personally, I am glad you had the sense to ask your question on this forum, and even though some of the responses have been - well, direct, it is good that you asked.

I hope you will come back to this forum often. There is only one way to learn, and the folks here will always do the best they can to help answer your questions.

Sorry that the answer about your "conversion" is not what you had hoped for, but at least you will not ruin a perfectly good Model 10-6.
 
Last edited:
You are NOT an idiot for asking questions. That is what this forum is for, it is about the experienced helping the inexperienced. Don't be afraid to ask questions. If it were my gun I would use some of the +P stuff for things like hog hunting. Buffalo Bore has a good load for that. Save up your money and when you turn 21 buy a good 357 mag. such as a model 27 or if you want to stay with a K frame a model 66 or 686.
 
Me239,

Much of what you read on the internet, including this forum, is based upon nothing more factual than "This is how I think it is", or "It sounds right to me".

I had been working on S&W revolvers for several years and had often wondered about the relative strength of various models of the same frame size. It made no sense to me that S&W would court errors in production by using different steels, and different heat-treating, for the various K-Frame models specifically, in both .38 & .357. Remember that basic forgings and blank parts would be indiscernable from each other if they happen to become mixed!

Here is what I was told at S&W when I was there for the Armorer's School in 1974, in response to a direct question about strength of the various models. The question specifically was, "Is there any difference between the .38 Special and .357 Magnum revolvers in either materials or heat-treating?" After some hesitation the answer I was given is NO, they are all identical!

So, taking your points, and other's comments, one at a time:

1) Chambering a Model 10 to .357 Magnum does not make it "basically a Model 19", there are several other differences.

2) The 1 9/16" standard cylinder is long enough for .357, the slightly longer M-19 cylinder in not needed.

3) Two mentioned it being an heirloom. The OP DID NOT SAY THAT, he said the gun was found in a pawn shop! READ and understand the question before giving an answer to a question that wasn't asked!

4) Cost. The only cost would be to purchase/rent a .357 reamer, anywhere from $35-125. Or you may find someone locally who has a reamer.

5) Ruin a Model 10? Don't be absurd. Removal of a few grains of metal from the front end of the charge holes is un-noticeable and has no effect on the safety or function of the gun. The guns is and will be a shooter, collector value is not a consideration.

6) The propensity if the Model 19 to experience barrel shank cracks. This is true because of the thin area at the bottom of the barrel shank. Model 10 barrels also crack there, but much less frequently. I wouldn't be concerned about this too much. Model 19 barrels are virtually non-existant, which is a problem. Barrels of any length for the Model 10 are abundant.

7) Performance? Any cartridge will generate lower velocities in shorter barrels. The idea that any .38 +P load will give higher velocity than any .357 Magnum factory load in an equivalent barrel length is absolute B.S. They do not magically switch positions in 2" barrels!

Am I recommending you do this? Absolutely not. I will repeat AirForceShooter's question, WHY? Will the gun wear more rapidly when higher pressure ammunition is used? Absolutely. This was one of the acceptable trade-offs considered when the Model 19 was designed. I can tell you one thing, and that is you will quickly tire of the recoil and go back to shooting standard .38 Special ammunition in the gun, unless you are a masochist. There is a solid reason the bull style barrel and extractor rod shroud were used on the Model 19!
 
Whoah... Ok people. The reason I asked is cause the guy at the store mentioned it as a thing that could be done. I never asked about anything besides the price. It is an heirloom in the way that it did belong to my grandfather and was given to me on my 18th birthday.
 
Hey Me, its ok , this is a good place to ask questions. Some folks get wound up about chopping up a gun, I dont, but in your case its a good thing you brought up the question.Its your gun, and later on you will probably be glad you didnt change it.
But the better reason is you will gain absolutely nothing( or very,very little) in a 2" gun changing to 357 mag. Get some good 38+p semi jacketed stuff and your good to go.
Tell you what, if you want to get a little more out of it, if you send me/or post a photo, I will send you a 4" barrel/ and the rods for it if I have one that fits its profile. I think they are the same as a 4" heavy barrel, but Ive never owned one . Then you can just pay a gunsmith to change it for you.
2" guns are harder to come by , so you might just leave it alone.
Anyway good luck and dont be afraid to come back to this forum to ask questions. bob
 
Whoah... Ok people. The reason I asked is cause the guy at the store mentioned it as a thing that could be done. I never asked about anything besides the price. It is an heirloom in the way that it did belong to my grandfather and was given to me on my 18th birthday.

Me239,

None of us (except a couple) are beating up on you. This was a legitimate question, but one that will elicit extensive remarks, even though that wasn't what you intended. You are far from the first to ask it!

Since you obviously reload, from one of your other posts, try this. 158 LSWC, 11.5 gr/2400 with either standard of magnum SP primer. This is a .38-44 load, but at one time S&W acknowledged the .38-44 was acceptable in the M&P. Just load a few and try them, you will see why you wouldn't want to shoot full snort .357 Magnums from the 2" M&P.
 
Keep in mind, I'm not able to purchase a .357 at the moment.

You have just inherited a revolver that has some sentimental value to you. You have interest in having a revolver that can fire 357 Mag.

Have you considered:

- keeping your M-10 stock

- if you have a good friend, have them purchase a 357 mag that you would enjoy shooting. Unless your state restricts loans (and most do not) which is allowed by the GCA of 68, you do a long term loan. For the next 3 years you shoot and care for this handgun. When you turn legal age to purchase a handgun, you legally purchase the 357 mag handgun from your friend.

I would never suggest anything that is illegal. And since you don't show your state of residence, make sure you are not breaking any laws doing what I suggest.
 
Me 239, two things come to mind. First, there is plenty if "condensed apple pie" on the internet,bad advice abounds[if you can call it advice] though not usually not on this forum. The LGS/ pawn shop has just as much or more misinformation as the internet. Second,if you want to convert your Mod.10 to a hand grenade this is a good way. All you have to do is pull the trigger! You don't even have to pull the pin and let the spoon go! If S&W thought this was a good idea they would not be making virtually the same guns,[with the exception of heat treating and a few upgrades], in .38 Spl. and .357 Mag.
I'm amazed any fool would suggest this to you,he does not understand the liability that could go with such asinine remarks. Listen to the guys here,save your Mod. 10 until other courses of action are available to you but don't ask a pick up truck do the job of a dump truck this ain't no hog huntin' gun!! Nick
 
The only "Plus" I can think of is a collector would consider your Model 10-6 "Miss-Stamped" by the factory and want it in his/her collection without first obtaining a "Letter" from Mr. Jinks.
 
- if you have a good friend, have them purchase a 357 mag that you would enjoy shooting. Unless your state restricts loans (and most do not) which is allowed by the GCA of 68, you do a long term loan. For the next 3 years you shoot and care for this handgun. When you turn legal age to purchase a handgun, you legally purchase the 357 mag handgun from your friend.

I would never suggest anything that is illegal. And since you don't show your state of residence, make sure you are not breaking any laws doing what I suggest.

I think I would be a little cautious about the "long term loan" thing as I think this type of transaction could be considered a "Straw Purchase" and would violate Federal Law?

While I'm not 100% certain as to the legalities of the "long term loan"... I would definitely check into the laws related to "Straw Purchases" before attempting this type of transaction.
 
Back
Top