Barrett 50 BMG 661 Gr M33 Ball Ammo 10 Round Box Our 50 BMG Ammunition Is Ready For Action. Encased In Barrett Head-Stamped Brass, Every Cartridge Is Loaded With Noncorrosive Powder And Primers as Well as a 661 Gr Projectile using State-Of-The-Art Machinery. Caliber: 50 BMG Bullet Type: M33 Ball Bullet Weight: 661 Gr Muzzle Velocity: 2800 Fps Rounds Per Box: 10 Boxes Per Case: 25 Casing Material: Head-Stamped Brass