Hornady 91361 Handgun Hunter 40 S&W 135 Gr MonoFlex 20 Bx/ 10 Cs Hornady Handgun Hunter Ammunition Is Built Around a Bullet as Rough And Rugged as The conditions And Game Demand. The MonoFlex Handgun Projectile Is manufactured With a Tough Copper Alloy That achieves Deep Penetration And 95% Weight Retention. Bullet Expansion Across a Range Of velocities Is Aided With a Proprietary Elastomer Material added To The Bullets Open Cavity. Upon Impact, The Elastomer compresses, then pushes Out And causes The Bullet To Expand faster Than a Standard Hollow Point Design. Caliber: 40 S&W Bullet Type: MonoFlex Bullet Weight: 135 Gr Muzzle Energy: 383 ft Lbs Muzzle Velocity: 1130 Fps Rounds Per Box: 20 Boxes Per Case: 10 Application: Hunting Casing Material: Brass