With the Ammo Boost Advantage, rifles can be converted to accept detachable magazines. Note: This detachable magazine requires Howa's Ammo Boost short action conversion floorplate trigger guard. This 5-round polymer magazine is compatible with Howa 1500, Weatherby Vanguard, Mossberg 1500, S&W 1500 and Interarms 1500 rifles in short action calibers: 243 Winchester, 7mm-08 Remington and 308 Winchester.