posted 25 June 2017 20:47
I saw an article recently that discussed a 357 AR. IT used a 5.56/223 case blown out to 357/358 diameter. Standard bolt head/bolt carrier group and 223 magazines (modified to function) were used in this build. The cartridge/rifle approximated the 357 Remington Maximum. The 357 Max reloading dies were used to load this cartridge. Does anyone know of a builder of an AR of this nature? The writer if the article built it for himself and his son. I would like to have a close copy of this rifle but I do not have the equipment or skills to do this myself. Who does this kind of work?

mcgowen will make you a barrel
http://mcgowenbarrel.com/shop/custom-ar-barrel/

Hi Duckhunter, Haven't checked in for a while after getting a new computer which didn't have my favorites on it. I'm the same Moleman who made the 357AR in the thread you spoke of. It's basically a 357Max-rimless run at 223/5.56 pressures. At first it was a "just because" build but a few years later the MI DNR changed the regulations for our shotgun zone and suddenly it could be used for deer hunting. When my son was old enough I made him one and he got his first deer with it at 142yds. The 180gr SSP bullet broke the opposite shoulder on the way out. He'll be using it again this hunting season. A few years back I switched to a 44x1.8" wildcat that matches 444 Marlin velocity and have been hunting with that in an AR10. Pmags are the easiest to modify by simply removing the bullet guide ribs in the mags. A "big bore" type feedramp works, along with a carbine length gas system on 16"-20" barrels. Haven't tried any longer than that. The chamber reamer has to cut a step for the case mouth to headspace on, so a standard 357Max reamer cannot be used. Manson Reamers made me a 357AR reamer at one point and has the print on file. If going that route I'd reduce the taper of the chamber from .005" to .003" so you don't have to trim the cases as often, and lengthen the freebore to .150" (allows you to seat the bullet out further and is necessary with some heavy cast bullets) which is what the last reamer I made has and is based off of my experiences from my other 3 reamers. I do not make barrels for others anymore but there has been some interest on the modern sporting rifle evolution forum and a small barrel maker is putting out feelers for a run of 10 of them. It's a fun niche caliber with low recoil, but it will never compete with something like a 450 Bushmaster which is a pretty good alternative.

On another site there is a barrel making putting out feelers for a small run of 357AR barrels. I currently do not make barrels for others, and I have no connection to the barrel maker other than saying it was fine with me if he wanted to make some. Just throwing that out there as an option for those who cannot make their own barrel. http://mdws.forumchitchat.com/post/3...post1300051429

Thanks for the information. I like the 357AR idea for several reasons. First is the cost of the build. I can use a standard carbine upper and just change out the barrel. Next, I have the 357 Max reloading dies, powder, primers and bullets. I have lots of 223/556.brass to convert. And finally, I like to tinker with wildcats.

I tried a few conversions this morning and these look a lot like a 357 Max when I finished. The body is slightly undersized through the middle as I don't have a body expander yet. I lost about 10% but I did not anneal these, just lubed well. Your directions to leave slightly long is well taken. My first attempts were too short to square up the case mouth and still be the required length. Can't wait to get a barrel.

Winchester did this in 1907. They called it the .351 Winchester. Why they made it a .351 and not a .358 who knows (not to be confused with .35 WIn.?)
I make cases for my '07 out of .357 Max brass. An ar in .351 Win. might be an interesting conversion??
C.G.B.

Hi cgbach, the 351 Win is very similar in concept. The same reasons it was popular 100 years ago still have merit today. Add in a longer case with more capacity, higher allowable pressure along with a locked breach and you get a cartridge that blows the doors off of the 351 Win. Quickload guestimate for a 180gr Hornady SSP, 2.235" COL, 34.8gr water capacity, 24gr W296- 2119 fps at 52,454 psi. The QL guesses have been pretty close for me. I have no way to verify the pressure but the Magneto Speed average for that load out of my sons 15.5" (welded on flash hider to bring it up over 16") was 2140 fps. That is not a max load, just one that shoots and performs well. When I was first discussing making one of these 6 years ago or so the 351 Win came up in looking at similar cartridges and one member on that site also had one. With all the areas that only allow straightwalled cartridges, I'd bet Winchester could bring out a limited number of reproductions and they'd sell.

That does rock. There is something about the stock shape and the blow-back action on my .351 that seems to accentuate felt recoil. The 9mm blow-back operated rifles appear to generate more recoil than they should. A gas operated .351 might be cool.
C.G.B.

Starline has a limited run of 223 basic brass, $90 for 250 cases. They'd need trimmed and possibly reamed to make 357AR (Max Rimless) which could be done in a single operation with a reamer pilot set up on your trimmer. I ordered some even though I'd just made about 500 more cases this fall. Can never have too much brass right? https://www.starlinebrass.com/whats-...w-products.cfm

Rehash of the 351 maybe, but with 223 brass and 357 bullets . . . components that are readily available today, and will be into the foreseeable future.
I went over there, read through 21 pages of posts in that thread and as near as I can tell they ordered and received all of the barrels that were made.
Never did figure out whether the barrels were ready for barrel nut and install in an upper though.