That's just test fire one, no worries, post up those measurements. Gas port size may need to be checked, that's gonna slow up getting that carbon seal on the gas block, might wanna just get it measured and have it though. Field strip and look everything over for odd wear marks. If everything looks fine send another box or two with the gas wide open. It can be frustrating when they don't take right off but it's always good to get some malfunction training in on a new weapon.