Winchester Super-X RIFLE 8x57mm Mauser 170 grain Power-Point Centerfire Rifle Ammo 20 Rounds. This bullet was named after Winchester's famed "Super-X" because of the "X" that is featured on the new Long X. This new design of bullet features a "crosshatched" look on the nose that is typical of the X class bullets Winchester is famous for. The "X" also appears on the base of the bullet where the "X" and "X" cross slots are located. These feature notches on the jacket of the bullet where the "X" and "Y" crosshatches are located. This allows the "X" to "unfold" or "unfold" as the bullet expands - expanding laterally then spreading out to provide maximum expansion. This assures the "X" factor of double-diamond shaped petals that offer maximum expansion and a "X" type of effect on the target. This is due to the "X" type of notching on the bullets cross section or "X" type cross slotted or "X" shaped bullet. Also a "Y" shaped jacket mouth or "X" type jacket provides maximum expansion. Specifications for Winchester Super-X Rifle 8x57mm Mauser 170 grain Power-Point Centerfire Rifle Ammunition: Manufacturer: Winchester Caliber: 7.92x57mm Mauser Number of Rounds: 20 Bullet Type: Soft Point (SP) Bullet Weight: 170 grain Cartridge Case Material: Brass Muzzle Velocity: 2360 ft/s Muzzle Energy: 2102 ft-lbs Application: Deer Package Type: Box Primer Style: Centerfire Lead Free: No Gun Type: Rifle Features of Winchester SUPER-X RIFLE 8x57mm Mauser 170 grain Power-Point Centerfire Rifle Ammunition: Power-Point Assures quick and massive knock-down Strategic Notching Provides consistent and reliable expansion Contoured JacketMaximum expansion performance Alloyed Lead Core Increases retained weight for deeper penetration Package Contents: Winchester SUPER-X RIFLE 8x57mm Mauser 170 grain Power-Point Centerfire Rifle Ammunition What is Winchester Super-X Rifle 8x57mm Mauser 170 grain Power-Point Centerfire Rifle Ammunition good for? The manufacturer thinks that it is best for deer.Winchester X8MM: Super-X Rifle Ammo 8x57mm Mauser Power-Point 170 grain 20 Rounds