357sig in rifle?

[stormbringerr]

has the ar-15 or any carbine been chambered to use the 357sig round?
seems like it would be a good round for a self defense rifle to me.

[DefensiveCarry.com]

[HotGuns]

I've never seen one, but I don't see why it couldn't be.

Its been done with everything else.

[40S&WMAN]

sounds nice, a hot 125 grain HP load going about 1800fps out of a 16" carbine

[BAC]

The worlds first gas operated 357 sig AR15

The guy put a ton of work into it, from custom parts to some impressive math, not to mention the trial & error to refine the weapon. Pride of ownership has got to be immense. Job well done, in my mind.


-B

[HotGuns]

WOW.

I'll bet that did take a lot of trial and error on his part. Great job though.

So there ya have it. It has been done.

[stormbringerr]

i bet our troops would like an ar-15 chambered in 357sig

[stormbringerr]

i cant see it because i was banned by the idiots that run that place a long time ago.
i never got an explanation or anything.
i think the mods/brothers over there have emotional problems and imagine things.

[BAC]

Gimme a moment to repost it all here, then:

I'd like to introduce to you all to my latest project. It is the world's first gas operated (direct impingement) 357 sig AR15.



I took her out to the range yesterday and finalized the gas port, buffer weight, and recoil spring/length. Function, feed, ejection all work just like a standard AR15.

Currently, I have the magazine system based upon sten magazines. I am not happy with the sten magazines for a few reasons. First, sten magazines do not have a bolt hold open feature after the last round is fired. Secondly, sten mags are old as dirt. Most of the mags I have are WWII surplus and they look every bit of it.

My next project with this gun is to retrofit a Hahn mag block to accept colt magazines so that the bolt hold open feature will work.

When I took her to the range yesterday, I brought with me a box of Winchester, speer gold dots, and two varieties of my handloads using VV3N37 (one set with light powder charge and the other with a more nominal charge). After opening the gas port little by little, I was able to get the Winchester, speer, and the VV handloads (with the heavier charge) to work 100%. However the VV light load would not bring the bolt back enough to engage the bolt catch. Not a big deal, because this gun will work with standard handloads and commercial ammo.

I have always wanted an AR chambered in 357 sig. What has stopped me from building such a beast in the past is that all previous systems were based upon the blowback design. Why is this a big deal you ask? Blowback in an AR with a hefty cartridge like the 357 sig would produce a LOT of recoil. In addition the chamber pressure of this round is approximately 40,000 PSI. As soon as the cartridge is ignited, the bolt begins to move back immediately, prematurely ejecting the case before the pressure has subsided. All blowback 357 sig guns leave the cases looking like .40S&W after ejection. This leaves the brass all torn up and in a non-reloadable condition.

With the DI gas operated 357 sig, the case is ejected from the chamber at the proper time, approximately when the bullet leaves the barrel. Because of this, the pressure has subsided enough to leave the case in the proper size and in a reloadable condition.

I was inspired by a person over at AR15.com who goes by the name of MartyW. He has pioneered the worlds first 7.62x25 Tok gas operated AR15. His work showed me that a project like this was possible. Anyway, enough of the credits.

I plan to send the barrel out to get it parked early next week. I left it unfinished because of the gas port work that was required.

After that is complete, I will take on the Colt magazine/bolt hold open project as time permits.

I will keep you all updated as to the Colt magazine project as it develops.

Anyway, thanks for the forum and I'm glad to share this with you guys here first, because I know there are quite a few 357sig nuts (like me) hanging around.

More details:

9mm barrel reamed to 357 sig. Barrel was threaded for a barrel extension and headspaced with a bolt that was opened up to accept 357 sig. Custom length gas port and tube. Gas tube length was established by a pressure vs barrel length chart. Bolt was opened up to accept 357 sig. Custom work on the ejector.

Then the discussion "why not a 9mm?" came up:

Interesting idea. However, I dont see the advantage of the .357 SIG over 9mm in a carbine.

The only reason I say this is that the overall cost of 9mm vs. .357 SIG and the fact that the muzzle velocity of the 9mm is enhanced when utilizing a carbine platform. Add to this the availability of existing 9mm AR parts and mags without the need to modify, for my $ Ill stick with the 9mm.

Good follow through though.

Interesting comments, however I don't agree about the performance of 9mm being close to that of the 357 sig. Fair enough though. I feel that because the 9mm is a blowback gun, a lot of energy is wasted because the case is being pulled from the chamber immediately upon ignition. Examine your cases and you will probably note all the soot that is evidence of this. In a gas operated gun, the case remains in the chamber longer until the gas pressure has subsided and has expended its energy pushing the bullet out the bore.

Next time I get out to the range, I will take several of my 9mm carbines (7", 10.5", and 16") and chrono some defensive loads and measure their performance. I will do the same with the 357 sig AR and report the findings. I suspect that they will not be close.

The AR parts I am using for this project are standard parts available anywhere. Nothing special went into this gun with a few exceptions. Let me put it this way, if a replacement part was needed, you would have no problem going out onto the open market and getting what you needed.

I cannot argue your point that 357 sig is more expensive than 9mm. However, due to the increase in 9mm prices, 357 sig has become more cost effective to shoot in relation to 9mm in the last few years. 9mm winchester white box used to cost about $11/100. Now it is $20/100. Standard winchester 357 sig is available at walmart for about $23/50 which is up from about $18/50. 9mm has risen at a faster rate than 357 sig and that has made it more cost effective than it used to be.

Enough of the comaparison shopping though. This AR was not created to compete with a 9mm. It is a specialty firearm that shoots a specialty round. If there is not enough interest in something like this on the open market, that would be fine. It will remain a one of a kind. I built this gun because I feel the 357 sig is a superior cartridge. I respect your opinion about the 9mm. So much so, that I own many 9mm based AR15's. But I can say this for sure, for those that feel like I do about the 357 sig cartridge, a 9mm just ins't the same thing.

What makes this gun special is that it has done something that has never been done before, it shoots a 357 sig pistol cartridge that operates a direct impingement gas system.

Here is some more convincing math:

I got a chance to chrono 9mm vs. 357 Sig. The results are as follows...

Both barrels are 7.5" and the two ammos compared are both winchester white box (standard plain jane, nothing hot or exotic)

9mm....
#1 1271.7 FPS
#2 1275.1 FPS
#3 1267.1 FPS
#4 1257.1 FPS
#5 1266.7 FPS
#6 1223.7 FPS
#7 1273.1 FPS
#8 1247.6 FPS
#9 1294.0 FPS
High: 1294.0 FPS, Low: 1223.7 FPS
SD: 19.7 FPS, CV 1.6%
MAD: 14.1 FPS, CV: 1.1%
Av: 1264.0 FPS, ES: 70.3 FPS


357 Sig.....
#1 1548.9 FPS
#2 1522.4 FPS
#3 1481.6 FPS
#4 1547.4 FPS
#5 1546.0 FPS
#6 1552.9 FPS
#7 1492.0 FPS
#8 1551.8 FPS
#9 1538.0 FPS
#10 1542.0 FPS
High: 1552.9 FPS, Low: 1481.6
SD: 25.6 FPS, CV: 1.7%
MAD: 20.2 FPS, CV: 1.3%
AV: 1532.3 FPS, ES: 71.3 FPS

Conclusion: No surprises. 124 grain 357 Sig shot about 300 FPS faster than 115 grain 9mm. If a lighter 115 grain 357 sig bullet were used there would me a much bigger spread between the two. I estimate that velocity would be about 1650 to 1700 FPS out of a 7.5" barrel. Likewise, if a heavier 9mm bullet were used from a 9mm AR, the velocity would be reduced to about 1050 to 1100 FPS.

The only comparison that this demonstrates is that the 357 sig is a much more powerful round than the 9mm. Let me put it this way, This gun cycles and functions fine with standard WWB 357 Sig ammo. I pulled a bullet from a 9mm WWB round and put the powder in a primed 357 sig case and set the 115 gr round nose bullet. I shot the above mentioned 9mm load 3 times today and it didn't have enough power to cycle the action to strip another round off the mag. It barely had enough power to eject the case.

So take it for what it's worth. This project has presented a lot of challenges and a lot of rewards. The gun is pretty much complete, I plan to tweak a few minor things here and there, but I believe I've settled on the final product.

Next, I may decide to make a 16" (non-NFA) length just to see how performance would be increased. Keep in mind, I was getting a tad under 1600 FPS out of a 7.5" barrel. A 16" barrel would produce numbers much higher .

Until then,

It was fun!

He chose not to get too technical on details because he did not want a company taking his hard work and profiting from it. He really did want to get regular production for this going, but just couldn't generate the interest for it.

In his words, "one of a kind."

This really sucks, too, since the guy did an outstanding job on this rifle and developed it the way firearms should be developed: mathematically and theoretically sound concepts, no half-hearted execution, and real trial & error to fine-tune and work out kinks.


-B

[BAC]

i bet our troops would like an ar-15 chambered in 357sig

Why?


-B

[stormbringerr]

they could carry more rounds per mag and gun would probably be still lighter than before.

i wish i had the gun he made it looks great.i would want it in a 16 inch barrel though for even more extreme velocity.

[dr_cmg]

I have wondered over and over why Beretta doesn't have a 357Sig version of the Cx4 carbine. They have a 9mm and a .40 cal. It would only require a 9mm barrel with the right chamber to attach to a .40 cal version. The same mags as the .40 uses would be used with the 357. I would swap my 9mm Cx4 for one of those tomorrow.

[OPFOR]

they could carry more rounds per mag and gun would probably be still lighter than before.

i wish i had the gun he made it looks great.i would want it in a 16 inch barrel though for even more extreme velocity.

Still not following you... The .357Sig case is wider than the 5.56N case, meaning fewer rounds in mags of the same size. Weight reduction of the weapon wouldn't be worth mentioning - the 9mm ARs that are out there don't weigh any appreciable amount less than the 5.56N versions. And, of course, you are losing tons of velocity, energy, and range by using the .357Sig (or any other pistol cartridge).

A .357Sig carbine is a great idea, but it is not suitable for general military use.

[mcp1810]

I am with OPFOR on this one. I think it is a neat toy but if you compare it with the 5.56 round it just doesn't work. Fatter brass= fewer rounds per magazine and the bullet itself weighs twice as much as the 5.56 but has much lower energy and the ballistic coefficient would limit your range. It could work in an urban environment but it would not give the troops the ability to transition from clearing a building to engaging a sniper 400 meters out.

It might make a nice urban law enforcement carbine though. If your agency carried .357 Sig pistols, and the powers that be are scared of giving patrol units something with a rifle round or say they cant afford to inventory the additional ammo, this could work!

[Rexster]

I would stand in line in the rain for one, if it would take P229 or P226 magazines, to match my duty/carry pistols, and was constructed military/police-tough. I like the idea of companion carbines for my handguns, even if they are NOT considered true all-around rifles. I cannot, however, afford anything custom along the lines of the one-off AR shown in the photos.

I already have a long weapon that shoots .357, but it is lever-action and chambered for .357 mag. It is no substitute for a true battle or assault rifle, but is a great short-range utility rifle, a Marlin 1894C. I like it so much that I now have an 1894CB on layaway. Neither will replace my .308 BLRs, but they have their place.

[Colin]

I have a Storm chambered in .40cal, if I lots of money I might get one with custom barrel in 357Sig, it's a round that makes a lot of sense for a carbine. I know the guy wanted to use stock AR stuff, I wonder if a piston system would work better for a pistol round than DI?