CO2-powered BB guns are great fun for plinking and target shooting--and none are more fun than the USP BB pistol. It holds 22 rounds in a heavyweight magazine that also houses the CO2 cylinder powering the pistol. It has an ambidextrous magazine release, integrated accessory rail and realistic hammer movement. This is a great practice pistol for 9mm USP owners. For just pennies a shot, you can shoot for hours!