Tailored after FN's production of U.S. Military issued carbines and made to FN's exacting specification, the replica stripped receivers are the heart of an authentic M4 or M16 build. Forged from 7075-T6 aluminum, machined, and broached to precise MIL-SPEC standards before anodizing, each receiver includes the markings of FN's U.S. Military production M4 and M16 receivers. Although the fire control housing is modified to block select-fire operation, each semi-auto receiver is the closest reproduction to the original DoD contract carbines.