.223 Wylde as 56 Nato Chamber Chrome lined barrel High Pressure Tested otherwise MPT bolt as well as barrel M4 feed ramps Magnetic Particle Assessment or perhaps MPI of the bolt and/or barrel Mil-Spec 11595E barrel metal to 4150 metal Perfectly staked gas key Shot-peened bolt.Magazine The magazine is actually one detachable container in which holds each ammo. Sometimes, their magazine fits inside the weapon as an example, within the hold of a pistol. For some firearms, that it attaches itself outside the gun.