Underwood Ammo 10mm Auto 140 Grain Xtreme Penetrator Solid Monolithic Nickel Plated Brass Cased Pistol Ammo 20 Rounds. Specifications for Underwood Ammo 10mm Auto 140 Grain Xtreme Penetrator Solid Monolithic Nickel Plated Brass Cased Pistol Ammunition: Manufacturer: Underwood Ammo Caliber: 10mm Auto Number of Rounds: 20 Bullet Type: Monolithic Bullet Weight: 140 grain Cartridge Case Material: Nickel Plated Brass Muzzle Velocity: 1500 ft/s Muzzle Energy: 700 ft-lbs Application: Target Deer Self-Defense Package Type: Box Primer Style: Centerfire Lead Free: Yes Package Contents: Underwood Ammo 10mm Auto 140 Grain Xtreme Penetrator Solid Monolithic Nickel Plated Brass Cased Pistol Ammo Underwood Ammo 648: 10mm Auto 140 Grain Xtreme Penetrator Solid Monolithic Nickel Plated Brass Cased Pistol Ammo 20 Rounds