Super-X Features The latest offering from Winchester the new 223 Rem BTHP is a highly accurate round that is excellent for varmint hunting and target shooting. Super-X Specifications Brand: Winchester Ammo Caliber: 223 Rem Model: Super X Series: Rifle Bullet Weight: 55 gr Rounds Per Box: 20 Casing Material: Brass Application: Varmint Target Bullet Type: Boat-Tail Hollow Point (BTHP) Muzzle Velocity: 3240 fps