PMC Ammunition .50 BMG 660 Grain Full Metal Jacket Boat Tail Brass Cased Rifle Ammo 10 Rounds. All PMC cartridges must pass through the rigorous inspection of the electronic powder check station. If the propellant in any cartridge varies by as little as two-tenths of one grain the system stops and that cartridge is discarded. Check out more of our supply of PMC Ammo for great savings on high quality ammoPMC Ammunition 50A: .50 BMG 660 Grain Brass Cased Rifle Ammo 10 Rounds