The main functional difference between the military's M16 and M4 rifles and a civilian AR-15 is the "burst" mode on many military models, which allow three rounds to be fired with one trigger pull.

This rifle is much, much cooler, though! Related: How to Build an M4 Shorty in Gray Zone Warfare Besides the iconic factor of using this weapon, the recreated CAR-15, built around an M4 in Gray ...