My buddy just put this AR together and we took it out today.

He inserts a mag and he can't pull the charging handle back.   I tell him to drop the mag and try to charge.  Ok, the charging handle functions, it's got spring in it.   Load mag and try again......same thing.

I take a round out (now the round is sitting on the right side of mag), slap the mag in and charge it.  Round goes into chamber like there was never a problem.

......BUT, now it doesn't fire.    Very light primer strike noticed afterwards.   I play around with it a little, but I'm no expert.  Try again, same issues.

Gun goes back into the bag before he really f's it up.

(we had more stuff to shoot and my AR ran fine, with the same mag and same ammo)



Anyone got an idea?

Could be several things.

First, if the mag started "full" and the top round was on the left, you might have stuffed 31 rds into the mag, since when full the top round should be on the right in most mags.  This extra round could have bound up your BCG because the stack of rounds in the mag exerted too much pressure on it.

Once you stripped that 31st round, you chambered a round and had a fail to fire.  Check that the hammer spring is not installed backwards as it is a common mistake and will lead to light strikes and the trigger pin walking out.

Certain there wasn't 31 rounds (ban State), but I get what you're saying.  Tried with only a couple rounds and when they started on the left it wasn't charging.  



I might just take it all apart for him and reassemble and see if I can't find something.