This magazine has a maximum capacity of (5) rounds. Only.300 Winchester Magnum and.338 Lapua caliber bullets will fit in this magazine. Steel construction allows it to withstand any environment while also preventing corrosion. Armalite included high-tensile compression springs in this magazine to ensure smooth transitions between the magazine and chamber. Factory original Steel 5 round magazine for the .338 Lapua Magnum and .300 Winchester Magnum caliber Ar-30 rifles.