colt ar15 in 7.62 x39

[Ball]

I picked up an colt upper A2 in 7.62 x39 and finally had a chance to shoot it at the range(100 yards) My problem is it ejects perfectly but does not pickup the next round.
I have it on a lower that i build myself and it works with my two ther uppers in 223.
Do you think its a buffer spring issue(spring too stiff for the caliber) or the mag. I'm using a brand new C-products 30 round which are suppose to be good quality for the 7.62x39 caliber??
Thanks any input would be appreciated..

[Hobie]

I'm not an expert but I understand that some of these are problematic. I don't know why. I would check on the AR15 forum.

[45stops_em_quick]

The 7.62x39 is really where the problem exists. The round cannot reliably feed from AR mags. The problem lies in the AR's straight magwell, and the geometry of the round. Colt originally sold 7.62 marked mags for the 7.62 rifles, but even those wouldn't feed reliably when loaded with more than 9 rounds. They were merely standard mags with a different follower.

So, in order to increase reliability in feeding and function, you must not load more than 9 rounds, and I would try using Colt 7.62 mags, or at least the latest anti-tilt follower in a mag if you're using 5.56 mags.

[Ball]

i had read that before too, the problem is i'm only putting in 5 rounds anyways.
I talked with another AR guy and he maybe it was short cycling because it ejects the spent round and then dry fires on an empty chamber. Does not pickup the next round.

[45stops_em_quick]

It could be short stroking, but the rounds could also be binding in the mag, and not available for pickup. Try checking the gas tube for corrosion, and or blockages, as someone may have been firing combloc surplus ammo through the upper. I'd also check the gas rings's on the bolt, and make sure that the gaps aren't aligned. Are you running the weapon wet? AR's like lot's of lube. Finally, I guess that you could try changing the buffer and/or spring, but I'd try cleaning the gas tube really well first and running straight mags. 10 or 20 rounders, preferable Colt 7.62 marked.

[Ball]

yeah i run them wet too, but i will give the upper a good cleaning including the gas tube, it does not appear dirty, but i did find the lower parts to be some what on the sticky side from old lube..
And try it once more before changing the buffer tube.
Thanks sometimes its the easiest things that we skip over, just need a reminder..

[shawnmt6601]

buy sme Cproducts mags. that should cure it