Hornady Handgun Hunter, 500 S&W, 300Grain, MonoFlex Projectile, 20 Round Box 9251 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 an elastomer material added to the bullet's open cavity. Upon impact, the elastomer compresses, then pushes out and causes the bullet to expand faster than a standard hollow point design.