Is this a 7.62x39 or a 7.62x51 aka 308? If it is a 7.62x51 it will not fit a 5.56 AR. It requires a completely different receiver. I'm assuming it is 7.62x39. You have to have special magazines as an AR-15 receiver will not handle AK mags. Also since it has a straight well, the curved 7.62x39 ammo might have missfeeds or jambs.

 

Sorry. It is by 39. It is a Windham Weaponry upper I picked up at a silent auction for $250, brand new. It came with one mag which is curved like an AK mag. I bought brass to sight it in and it worked great but the ammo was as much if not more than 5.56. I would love to stock up on cheap steel ammo but not if it is too dirty or tough on the bolt/extractor.

 

You can give it a shot but even my brother, who loves his 762x39 uppers, admits he only uses brass ammo.

 

If not mistaken, I don't believe the 7.62x39 upper will work with a standard AR lower. The 7.76x39 cases have a significant taper as compared to 5.56. Of course like I said, I may be wrong.

I'm building a 300 AAC Blackout upper for this reason. The blackout uses a standard AR 5.56 BCG, magazines, and lower.

Added: Looks like I was in fact wrong in that standard AR 15 lowers will work with the 7.62x39 upper. There seems to be reliability issues with this configuration though.

 

the only issue will be 7.62x39 mags... c-products makes some decent ones that fit AR wells...

you should be able to shoot whatever ammo you want, but know that AR bolts were not designed for the base diameter of the x39 cases.... as a result CMMG i think made a mutant that essentially is using a turned down AR10 carrier and bolt that works with a standard AR 15 buffer tube... now they also use a different lower to use AK mags, but provided your setup i dont think there is much you can do in terms of ammo selection to accommodate the limitations of the AR15 type bolt.

 

I hate it when I think of things too late. The upper came with a full bolt carrier group so they must have made it to properly fit the case and it "should" be robust enough for the steel case. Now the question is this; Is it worth shooting that really dirty ammo? I think it may be just due to the lower cost ammo.

 

Run the steel cased ammo and find out. This is the same debate that goes on about 5.56 steel cased ammo. In the long run you save enough money to buy multiple new barrels to counteract the premature round of the harder projectiles.

I personally will not own any AR that will not reliably run at least 100 rounds of steel cased ammo. It would really suck if that's all you could find at some point and your rifle wouldn't run it. Almost all new production ARs have no issues with this. I run brass typically though.

You got the upper for cheap so have fun with it and some cheap ammo. How "dirty" the ammo is really doesn't make a difference unless you're going to shoot thousands of rounds without cleaning it. Which is not recommended and quite dumb.

 

Great answer

Very true. Thanks for the rational thoughts.

 

steel case ammo wont hurt it at all, that's a interweb myth.


been used for over a 100 years and 2 world wars.....

 

One thing that I forgot to mention was to clean the chamber VERY well after shooting a decent amount of steel cased ammo before attempting to switch over to the brass cased ammo. The steel doesn't expand as well in the chamber and as a result it will allow the gas and carbon fouling to stick to the chamber walls. If you dump in a brass cased round immediately after it will expand more and is likely to stick in the chamber. I have never had this happen to me personally because I have never done it in that sequence but I just wanted to give you a heads up in case you were thinking about running both styles in a single range trip.

 

I have never had any issues with steel or brass ammo in my AR's, but I clean the chambers a lot. Just remember this: brass before steel is a hell of a deal, steel after brass is a pain in the ass.

 

Bet the little gas tube would benefit from a good cleaning after running filthy 7.62X39 gasses through it?

 

I was never good at that. what is the best method?v a really long pipe cleaner probably isn't it.

 

IDK, they make the long pipe cleaners for cleaning the gas tubes, I have access to a weapons sized ultrasonic cleaner so once in a while I just drop my rifle in that thing.

I suppose some good cleaner and the pipe cleaners would work.
I was more wondering if anyone with a 7.62 upper has run into any problem with the gas tube after running dirty ammo.