Hornady Superfomance 5.56 Nato 55 Grain Copper Solid CX Brass Cased Centerfire Rifle Ammo 20 Rounds. It uses the highest quality cases and primers available which equals consistent components that translates to consistent shooting in the field. The Superformance ammunition is 100 to 200 fps faster than conventional ammunition and is safe for use in all firearm types including semi-autos lever guns and pump actions. Specifications for Hornady Superfomance 5.56 Nato 55 Grain Copper Solid CX Brass Cased Centerfire Rifle Ammunition: Manufacturer: Hornady Caliber: 5.56x45mm NATO Number of Rounds: 20 Bullet Type: Boat Tail Soft Point (BTSP) Bullet Weight: 55 grain Cartridge Case Material: Brass Muzzle Velocity: 3175 ft/s Application: Medium Game Package Type: Box Primer Style: Centerfire Sectional Density: 0.248 Bullet Core Material: Copper Package Contents: Hornady Superfomance 5.56 Nato 55 Grain Copper Solid CX Brass Cased Centerfire Rifle Ammunition What is Hornady Superfomance 5.56 Nato 55 Grain Copper Solid CX Brass Cased Centerfire Rifle Ammunition good for? The manufacturer thinks that it is good for medium game.Hornady 812544: Superfomance 5.56 Nato 55 Grain Copper Solid CX Brass Cased Centerfire Rifle Ammo 20 Rounds