Winchester Super X .223 Remington 55 Grain Boat Tail Hollow Point BTHP Brass Cased Centerfire Rifle Ammo 20 Rounds. For decades hunters and shooters have relied on Winchester Super-X rifle ammunition. Best known for time-proven dependability the rounds offered include a hollow point and lead core for rapid expansion on game as well as a thin-wall jacket which reduces engraving forces for improved accuracy. Specifications for Winchester Super X .223 Remington 55 Grain Boat Tail Hollow Point BTHP Brass Cased Centerfire Rifle Ammunition: Manufacturer: Winchester Caliber: .223 Remington Number of Rounds: 20 Bullet Type: Boat Tail Hollow Point (BTHP) Bullet Weight: 55 grain Cartridge Case Material: Brass Muzzle Velocity: 3165 ft/s 3240 ft/s Muzzle Energy: 1223 ft-lbs Application: Competition Package Type: Box Primer Style: Centerfire Lead Free: No Features of Winchester Super X .223 Remington 55 Grain Boat Tail Hollow Point BTHP Brass Cased Centerfire Rifle Ammunition Varmint Hunting & Target Shooting Highly Accurate 3165 FPS Package Contents: Winchester Super X .223 Remington 55 Grain Boat Tail Hollow Point BTHP Brass Cased Centerfire Rifle Ammunition What is Winchester Super X .223 Remington 55 Grain Boat Tail Hollow Point BTHP Brass Cased Centerfire Rifle Ammunition good for? The manufacturer says that it is good for competition.Winchester W223HP55: Super X .223 Remington 55 Grain Boat Tail Hollow Point BTHP Brass Cased Centerfire Rifle Ammo 20 Rounds