Sierra Outdoor Master cartridges utilize innovative components and production processes that deliver an economical cartridge suitable for all purposes. Packed with hard-hitting terminal performance. Designed for magazine length and reliable feeding in an AR platform. Cartridges are loaded with brass casings, making reloading with conventional equipment easy and economical. *Note This ammo uses mil-grade primers. Best for use in AR-15s. Primer pockets must be reamed or swaged in order to reload. Specifications: 223 Rem 55 gr Hollow Point Boat-Tail (HPBT) 20 Per Box/10 Cs Caliber 223 Rem Application Hunting Bullet Type Hollow Point Boat Tail Bullet Weight 55 gr Muzzle Energy 1281 ft lbs Boxes Per Case 10 Rounds Per Box 20 Casing Material Brass Muzzle Velocity 3240 fps