my first ar 15 build please help...

[EddieDaGreat]

Hello every one . Like the title says I am building my first ar 15 and need a lil bit of help.. the problem im having is that I want to build it in the 7.62 by 39 caliber.. I already have my lower complete and I have the stripped upper now the question is what kind of bolt or bolt carrier assembly do I have to use or what parts are going to have to be different than a regular 223.. or can I use all of the regular parts of the 223 and just change the barrel

 

[quepasakimosabe]

Bolt assembly and barrel assembly are what you need, the bolt carrier and firing pin are interchangeable. You look around on say brownells hard nuff you find them. I would strongly suggest that you either purchase headspace gages or see a gunshop and borrow theirs to check it once your done. Hope that helps. Torque specs on the barrel still the same, 30 ft-lb minimum, Moly grease will b e your friend here on those barrel threads, stay away from cheap steel cases unless you like swapping extractors.

 

[scsov509]

stay away from cheap steel cases unless you like swapping extractors.

We've run almost nothing but steel our AR's and have had no such problems at all through many, many thousands of rounds. The bigger issue with surplus rounds in a 7.62x39 AR is hard primers with a standard AR firing pin which is slightly too short to reliably ignite them. A heavier hammer spring has worked good for us, though I know some guys actually modify their bolts by taking a few thousandths off the end too allow a little deeper penetration of the firing pin for those harder primers.

The biggest issue you'll have is finding reliable magazines, because they're just a lot more scarce on the 7.62x39 AR platform. There's a great sticky posted here on this caliber in the AR that will probably answer most of your questions and help give you some other ideas as well.