Heckler & Koch, encouraged by the success of the G3 automatic rifle, developed a family of small arms consisting of four types of firearms all based on a common G3 design layout and operating principle. Despite its higher cost, the MP5 remained the more successful of the two options. In 1999, Heckler & Koch developed the UMP, the MP5's successor. The MP5 is one of the most widely used submachine guns in the world, having been adopted by over forty nations and numerous military, law enforcement, intelligence, and security organizations. There are over 100 variants and clones of the MP5, including some semi-automatic versions. The Heckler & Koch MP5 ( German: Maschinenpistole 5) is a 9x19mm Parabellum submachine gun, developed in the 1960s by a team of engineers from the German small arms manufacturer Heckler & Koch. 9×19mm Parabellum (MP5A1, A2, A3, A4, A5)ġ5, 30, 40, or 50 round detachable box magazine and 100-round Beta C-Mag drum magazine.Tilo Möller, Manfred Guhring, Georg Seidl, Helmut Baureuter

9 inch or 10 inch quad rail