Just wondering if this would be possible. I'd like to make it gas operated like MartytW's 7.62X25mm conversion.

I see the bolt from the 6.5mm Grendel round would fit the .357's case rim and 9mm barrels aren't hard to find.

I don't have any idea what would have to be done to the gas system to make it run. It would be really nice to have some adjustment to be able to run .38spl type loads with a supressor.

The other big question is magazines. I'm thinking someting like the Tromix .50AE kit or a .357 Desert Beagle mag wiht an adapter block.

What am I missing?

357 AR would rock!  Just make sure you shoot jacketed bullets only or it might clog up the gas system.    It might be easier to just use a 357 SIG instead since 40 SW uppers exist already all thats needed is a barrel.

hehe i like that Desert Beagle part!

Gloating, it's what I do best

What would be awesome would be 357/223.

Quoted: 357 AR would rock!  Just make sure you shoot jacketed bullets only or it might clog up the gas system.    It might be easier to just use a 357 SIG instead since 40 SW uppers exist already all thats needed is a barrel. hehe i like that Desert Beagle part!

Blow back systems don't use the gas system.  Correct?

Quoted: Quoted: 357 AR would rock!  Just make sure you shoot jacketed bullets only or it might clog up the gas system.    It might be easier to just use a 357 SIG instead since 40 SW uppers exist already all thats needed is a barrel. hehe i like that Desert Beagle part! Blow back systems don't use the gas system.  Correct?

Correct

Would a .357 round fit in a M1 carbine mag??

In first place, I don’t understand why anyone would want a .357/.38 AR. And you’d think if there were any “need” or market for it, someone would have done it by now. The AR system has only been on the market for 40 years.

Secondly, I’d think that anything you could do with a .357/.38 AR could be done nearly as well with a 9mm. I wouldn’t think any possible advantage would be worth the hassle of trying to cobble the thing together.

All that said, however….

If you want to pursue this, your biggest problem is prolly going to be a suitable magazine, and then a suitable bolt. I can solve both those problems for you in one stroke.

Back in the mid-‘70s, Jeff Cooper sort of “magnumized” the .38 Super by making brass from cut-down .223 empties (which of course is much stronger in the head area than normal .38 Super cases). IIRC he was getting near-.357 velocities, at least with lighter bullets. You could do the same thing. You could reline a shot-out .223 barrel to .357 bore and then ream it to .38 Super. You might even be able to rechamber a standard 9mm barrel (not sure if this would work or not). You could even go Cooper one better by cutting the .223 brass to longer overall length, as you are now limited only by the AR .223 magazine, not the shorter handgun mag.

Of course, if you keep the case at normal .38 Super dimensions, you could then carry a handgun chambered for the same ammo.

Quoted: Gloating, it's what I do best i5.photobucket.com/albums/y164/RyanJR/IMG_1871.jpg

It that really a .357 Mag? or a .357sig? What kind of magazine and block?

I don't want a .357sig, 9mm, .38super or any strange wildcat. I want a .357Magnum. Why? I want one.............because I want one. Reason enough?

Out of a 16" barrel the .357Mag can push 125grain JHP's @2000fps or 180grain @1800fps. That gives it the same kind of energy numbers as the .223 but with a much bigger bullet. I don't think the 9mm in a blowback setup is going to do that.

Quoted: Quoted: Gloating, it's what I do best i5.photobucket.com/albums/y164/RyanJR/IMG_1871.jpg It that really a .357 Mag? or a .357sig? What kind of magazine and block? I don't want a .357sig, 9mm, .38super or any strange wildcat. I want a .357Magnum. Why? I want one.............because I want one. Reason enough? Out of a 16" barrel the .357Mag can push 125grain JHP's @2000fps or 180grain @1800fps. That gives it the same kind of energy numbers as the .223 but with a much bigger bullet. I don't think the 9mm in a blowback setup is going to do that.

It's a 357sig, someone mentioned the round so I figured I post a pic of mine. I think the 357mag would make a neat conversion though.
I'm running a Colt type system using an RRA mag block and modded uzi mags.

Im sure it could be made to run in gas mode but feeding it would be an issue. The strait case with a larger rim? Just my $.02. Ron

Yeah-I suppose it could be possible but let me be the devils advocate here and point out some possible problems to be dealt with.
1) rimmed case is going to be a PITA,not sure how DE deals with it.Rimmed cases just don't stack well.
2)Factory ammo comes with quite a selection of power levels with a huge variety of bullet weights,shapes and sizes,along with various OA cartridge lengths. Gun could be set up to run with anything but swapping around would cause tricky problems.Adjustable gas block ?
3)Bullet jackets constructed for 1200fps-1500fps are not going to  act properly when pushed 300-500fps faster.

One  last point--after you make yourself crazy cooking this thing up and getting it to run right,let us know how you did it because it sounds like a lot of fun!!!!!!!!

Its a great idea, but I don't know what magazine would be suitable for such a project.

I have heard of a .357 wildcat, it is a 10mm magnum case necked down to .357".  Loaded with 200 grain spitzer bullets, it almost fills an AR15 6.8mm  magazine.  Sort of like a 9 x 25 Dillon on steroids!

I have no idea of the ballistics, but I would suspect they would match or beat anything the .357 magnum could do.  The main drawback being that bullet selection is limited.

Randall was working on the 357 10mm mag thing, but I think it is on the back burner. There was another site on a guy that had one in a contender, he was getting around 1900 fps with bullets in the 140 range.  It would use a 6.8 bolt (think 338 spectre)

Bullet selection should be huge as you could choose from the 357/358 crop.  Main advantage would be the low penetration of the 125-158 grn 357 bullets at higher velocities to aid expansioin.  I think it would be a great short range urban round.  I looked at it a while, just did not want to bite the bullet on a reamer yet.  10mm mag brass forms easily when run into a 357 sig die.  I thought about the 357 automag also, but I am concerned it would sheer the locking lugs like the BR series of cartridges.

The feed lips on an m1 carbine magazine would need to be re-formed, but the length is right except for the heavier bullets.  If you smack a loaded mag, they all fly out.  I would think recoil would be a non issue.  They look like they would feed out of the AR magazine with rifle bullets, I don't know about the pistol bullets. For rifle bullets, you would need to find bullets designed for the 35 rem or such that have a thinner jacket.

Quoted: Just wondering if this would be possible. I'd like to make it gas operated like MartytW's 7.62X25mm conversion. I see the bolt from the 6.5mm Grendel round would fit the .357's case rim and 9mm barrels aren't hard to find. I don't have any idea what would have to be done to the gas system to make it run. It would be really nice to have some adjustment to be able to run .38spl type loads with a supressor. The other big question is magazines. I'm thinking someting like the Tromix .50AE kit or a .357 Desert Beagle mag wiht an adapter block. What am I missing?

I don't know if this fits in with what you want but one of the dealers here on ARFCOM has a 357 auto project that uses some existing AR parts although I don't believe it's a gas system.  You can see it here;
www.ar15barrels.com/prod/357auto.shtml

This is the round.

This is the rounds in the 6.8 mags.


Maybe Marty can work this one into his gas system project!

I talked to Randal about this project a long while back as we were thinking along the same lines.  With all the 6.8 and 6.5 stuff along with his others, I don't think he ever went into production of the barrells.  I do believe he did have a reamer made.

Quoted: I don't want a .357sig, 9mm, .38super or any strange wildcat. I want a .357Magnum. Why? I want one.............because I want one. Reason enough?

Oh, I thought you were serious. My bad. Sorry to have wasted your time. Won't happen again.

Quoted: I don't want a .357sig, 9mm, .38super or any strange wildcat. I want a .357Magnum. Why? I want one.............because I want one. Reason enough?

Sorry Rangie -- I missed the above statement! As you said, the magazine is the problem.

Quoted: I see the bolt from the 6.5mm Grendel round would fit the .357's case rim and 9mm barrels aren't hard to find.

9mm is .355"  I think squeezing a .357" bullet into that would cause problems.  But if ar15barrels.com is making .357" bore barrels for his 10mm/.357 project he could probably make you one you could chamber to .357 mag.

The other big question is magazines. I'm thinking someting like the Tromix .50AE kit or a .357 Desert Beagle mag wiht an adapter block. What am I missing?

Years ago somebody, maybe Tromix, made .44 Mag uppers.  I asked then about .357 uppers then and they said they could do it, but it was way more than I could afford at the time (or now).  I believe they've stopped making the .44 uppers since then too.  

I don't remember any details, but I think they might have used the Desert Eagle mags.  That sounds like a good place to start if they'll fit the mag well.  I don't remember if they were blowback or gas.  I'd guess blowback, but I've heard 9mm is about the limit for blowback actions.  Are rounds like the .458 SOCOM or .50 Beowulf blowback or gas?

You could probably use the 357 maximun (super mag) case.  Problem would be the rim, unless you have access to a lathe and want to turn the case head to the profile of the 223 round.  The 357 max case is supposed to be made from the draw of 223 cases.  Think a 223 rimmed case blown out to accept .357 bullets.  Thought about it as I have a 357 max reamer and some barrel blanks and an extra barrel extention.  Probably push a 180gr bullet to 2000fps and use standard AR mags and standard 223 bolt.  Only if we had the cases, everything else would be easy.

After fooling with some .357 rounds and a couple of AR mags I don't see any way they could be made to work. I think the only option would be the DE Mags, which is kind of dissapointing since they only hold 9 rounds.

The 10mm Magnum to .357 wildcat looks really neat. I imagine loaded to it's full potential in the AR platform it would leave the .357 mag in the dust.

The big appeal for me to use the .357 mag is that I allready by ammo for it by the case.