The Heckler and Koch MP5 Submachine gun is a lightweight, air-cooled, magazine-fed, delayed blowback operated, select-fire weapon that can be shouldered or hand fired. The H&K MP5 submachine gun is chambered for various pistol cartridges to include 9x19mm Luger, .40 S&W, and 10mm Auto. It fires from a closed-bolt position in semi-automatic, 2 or 3-round burst, and sustained fire modes. The weapon utilizes the unique H&K roller-locked bolt system used commonly throughout the H&K family of small arms.