M4/M16 Spare Magazine HIGH CAPACITY 300 Rounds Metal Construction, brand new in package. Lancer Tactical Metal M4/M16 Airsoft Rifle Magazine, 300 Rounds, Tan. This is a HIGH QUALITY metal airsoft magazine, from the most trusted name in Airsoft. This magazine will only operate with 6mm airsoft BBs and cannot be modified in any way to hold real rifle ammunition.