The MP5 is a 9mm submachine gun of German design, developed in the 1960s by a team of engineers from the German small arms manufacturer Heckler & Koch of Oberndorf am Neckar.
The MP5 is currently one of the most widely used submachine guns in the world, having been adopted by numerous law enforcement agencies and special forces groups. In the 1990s, Heckler & Koch developed the UMP , the MP5's successor, though both remain in production.
The primary version of the MP5 family is the MP5A2, which is a lightweight, air-cooled, selective fire delayed blowback operated 9x19mm Parabellum weapon with a roller-delayed bolt. It fires from a closed bolt position.
The fixed, free floating, cold hammer-forged barrel has 6 right-hand grooves with a 1 in 250 mm (1:10 in) rifling twist rate and is pressed and pinned into the receiver.