It wasn’t “a few extra grains”. The round was severely overcharged, like 3x normal pressure generated by the round. 50k PSI normally generated by the round in the chamber vs 180k PSI necessary for the weapon to fail. With a replacement rifle, he test fired every other round he had from that batch and had no issues, but a round they purposely made overcharged (190k PSI) blew the thing up again in the same way.