Welcome from AZ! Need a few more specifics , like is it new ? If so ... Rack the BCG About 100 times with some lube on it to mesh the upper to the bcg. When you go out next time take a DPMS metal mag with you and a different kind of ammo ,like 168 Gr projectiles. Wait for it.... Lube it up with Mobil One or Castrol GTX ! Dripping Wet, Running down your arm, Splashing in your face and dripping on the floor !!! This will break in your gun , 50 to 100 rounds . Run a patch through the barrel every 10 to 20 rounds. The 147 gr bullets are not the best to be used for breaking in your gun. Also the buffer is a little heavy. Magazine could be the other issue, try the metal mag with the 168gr bullet then the Pmag with the 168gr bullet. Good luck and tell us what happens.