AR-15 parts (7.62x39mm)

**mojo** · January 14th, 2010, 10:19 PM

Originally Posted by lexnaturalis

I'm getting that vibe from this thread.

I suppose it's worth the extra money to do it right and at least have a complete upper assembly for each cartridge. All that re-assembly sounds like something I could royally screw up.

Uppers are cheap ... $93.10

http://www.bravocompanyusa.com/Upper...%20-m4%202.htm

**JayBell** · January 14th, 2010, 10:25 PM

also, be aware... 7.62x39 bolts break locking lugs very easily... its not a safety issue per se, but you DO have to replace them when it happens

the reason for this is that the case head recessmfor the AR is based off the 5.56 cartridge.... once you hog it out to fit the x39 head, you weaken the bolt head,and lugs break off...

after the 4th Colt bolt broke on mine, I gave up on the x39 system for the AR15...

**lexnaturalis** · January 14th, 2010, 10:33 PM

Originally Posted by 39flathead

I also was going to go the 7.62 route, but after researching it, the mags out there are problematic and after serious consideration, I decided against it.

A few posters in this thread mentioned some mags that were good. I looked a few other places and heard good things about the C products mags. I'm hoping they're worth while.

I still haven't decided if I'll build the 5.56/.223 version first or the 7.62x39. I'm still a tad overwhelmed with all the possibilities of parts. My Excel spreadsheet is quite immense at this point with all the possible combinations

**Dragracer_Art** · January 14th, 2010, 11:28 PM

Don't waste your time or money building a 7.62x39 AR15. I've never seen one run reliably... Save that Russian caliber for the Russian guns. I've tried it on several different guns I owned and never did get any of them to run 100%.

Stick to .223/5.56 in the AR15 if you are new to them. They are fussy enough as is sometimes just using the round it was designed for.

Just FYI... the difference between the 7.62x39 and 5.56x45 AR15 parts are the bolt and barrel. Std mags may/may not work, with reduced capacity. There are some 7.62x39 specific mags available if you are really hellbent on doing it.

The M16 bolt carrier has add'l metal on the underside in the rear to trip the autosear. I always prefer the M16 carrier due to the shrouded firing pin and added weight which helps reliability.

**mojo** · January 15th, 2010, 09:00 AM

Originally Posted by lexnaturalis

I still haven't decided if I'll build the 5.56/.223 version first or the 7.62x39. I'm still a tad overwhelmed with all the possibilities of parts. My Excel spreadsheet is quite immense at this point with all the possible combinations

Since this is your first one .. go with 5.56. You can always add 7.62 later. Go with the original first them mess with the "other" calibers.

**1832** · January 15th, 2010, 12:37 PM

FWIW, check out ar15.com and search in the AR Variants Forum. You'll see what experiences others have had with this setup, and what this round can do when its fired in an AR platform. Its ballistics are similar to the old 30-30 Winchester and its good to go out to 150 yds.

**Jackal** · February 26th, 2010, 02:47 AM

Originally Posted by 1832

As Mojo mentioned, some of the 7.63x39 30rd AR mags were problematic, however, the current crop of C Products 30 rd mags run fine.

I've not read the C-products mags work well. Last I read people were having trouble, still, with there 3rd generation mags. This was a few months ago, has anything changed? Do you have a link?

To the OP, it seems like an xcr from rob arms would allow greater caliber convertibility. The kits are 300-500 though. The price is higher but it is easier from what I read. I do not own an xcr.