Okay, here's the problem.  My carbine will fire one round, then the bolt will catch halfway through loading a fresh cartridge.  I retract the bolt, dump the round that didn't feed, and chamber a fresh round.  It fires again, and hangs up again.  Upon examiniation, I found the firing pin retaining pin bent, took it to a local gunshop, and he worked over the hammer a little.  Took it back to the range, same problem.  

The kicker is that the old A1 upper I had worked fine, usually using Wolf or Winchester White Box fodder.  The new lightweight carbine upper worked fine when I put it on.  This upper worked fine with both a stubby "LE" stock, it worked fine with the A1 stock.  Post 9/13 I put a 6 position RRA stock on it, and now I've got problems.  Is there any reason that the new stock would lead to this problem?  Please help, 'cause if it is I can hear Feinstien laughing at me and it's irritating...