In the canon of firearm law, the MP5 (MachinennPistole), developed by the German company Heckler & Koch (H & K), stands above the rest as the de facto king of the submachine gun.

H & K was founded in 1948 by former Mauser Werke employees Edmond Heckler, Alex Seidel, and Theodore Koch. Heckler was a former Mauser plant manager, Koch a former engineer, and Seidel, an industrial mechanic. Because of post-war restrictions on German production of weaponry and ammunition, the company originally manufactured machine tool gauges, sewing machine parts, and related products. It was about a decade later, when those restrictions were removed, that the company moved into firearm development. 

MP5 was originally labeled the HK54. Its earliest progenitor was the M.Kb. Gerät 06, which no one but the cognoscenti has heard of, and the StG 45, which is only marginally better known. Both those weapons utilize a roller lock operating system that would later be incorporated into the much-better-known G3 rifle. The HK G3 battle rifle, for all its size, is just one generation older than the original MP5 and had much to do with that weapon’s inspiration. 

MP5 was originally intended for sale to West German (and possibly other, non-Soviet Bloc) police forces. It began in 1964 as part of “Project 64”, which began the development of a family of four kinds of small arms. Each group centered around a different caliber, but all weapons were predicated on the H&K G3’s design and operating system. Those calibers were: 

1. 7.62×51 NATO

2. 7.62×39 M43

3. 5.56x45mm NATO

4.  9x19mm Luger

The MP5, in its incarnation as the HK54, was in the latter group (Group 4). It has been in service for over half a century and is ubiquitous with many the special forces around the World including Hong Kong’s Special Duty Unit (SDU), Small Boat Unit (SBU) and Airport Security Unit (ASU).