LOWER RECEIVER: THE STANDARD DPMS A-15 MULTI-CALIBER OR 5.56 LOWER RECEIVER FITS THE .50 BEOWULF UPPER RECEIVER WITHOUT MODIFICATIONS Notes: DPMS A-15 lower receiver and Alexander Arms .50 Beowulf barrel and upper assembly because it uses standard AR-15 dimensions. .50 Beowulf Barrel Specifications Caliber: .50 Beowulf (12.7x42mm equivalent dimensions) Standard Length: Commonly 16 inches rifle Twist Rate: 1:20-inch Right-Hand (RH) twist Material: 4150 Chrome-Moly Nitride or phosphate finish Muzzle brake This rifle comes with what you see in the photos including four 10 round, one 7 round, and one 4 round magazine.