One of the most popular submachine guns ever produced, the Heckler & Koch HK MP5 ("Maschinenpistole 5") became a common sight throughout the latter Cold War years. The type was adopted by many special forces groups as well as security elements for its sound design and utmost reliability in close-quarters actions, proving a major market success for the German concern. While having shown its age since (the firearm was designed in the 1960s), the MP5 continues widespread service today (2013) although it has been long superseded along Heckler & Koch lines by a more modern offering - the HK UMP (Universale Maschinenpistole), a lightweight, less expensive platform made fully modular by incorporation of accessory rails about the design.
Design work on the original MP5 product began in 1964 and spanned into 1966 while being officially attributed to the collective minds of Tilo Moller, Manfred Guhring, Georg Seidl and Helmut Baureter. The original working model was then known as the "HK54" to which this eventually became the "MP5A1" mark. Production commenced under the Heckler & Koch brand label in 1966 and, amazingly, continues even today (2013). Success of the series could be attributed to HK's use of its existing and proven automatic rifle components which became widely successful in previous company offerings at the military level. Basic construction of the MP5 involved use of steel and plastics for a lightweight end-product which was also compact - key qualities for any submachine gun. Basic models were available with simple single-shot and full-automatic fire modes while a three-round burst function was eventually introduced into the family line. Military variants then appeared with integrated suppressors fitted over the barren for reduced sound operation (to produce the "SD" - "Silenced" - line) and this version went on to be used with tremendous success, alone producing six major sub-variants under the SD designation. Various optics and accessories could be mounted along the receiver or forend of standard MP5s as needed, considerably broadening the tactical reach of the operator in-the-field. Basic iron sights were standard forward and aft.
While primarily chambered for the 9x19mm Parabellum pistol cartridge, HK eventually released MP5 models chambered for the 10mm Auto and .40 S&W. The standard 9mm form was fed from a 15-, 30- or 40-round detachable box magazine though other variants could make use of the 100-round Beta C-Mag ammunition drum. The action consisted of a roller-delayed blowback system utilizing a close bolt arrangement - the same as featured on several full-length HK automatic rifles - proving itself both accurate and reliable. Rate-of-fire, loaded/empty weights and effective ranges all varied depending on the chambering and production model in question.
The first definitive MP5 form became the MP5A2 with its fixed solid shoulder stock featuring single-shot and full-automatic fire modes through a clearly-marked selector switch along the side of the receiver. The MP5SFA2 was similar though with only a single-shot, semi-automatic firing capability. The MP5A3 brought about use of a collapsing shoulder stock with support for single-shot or full-automatic fire. The MP5SFA3 became a carbine version of the MP5A3 complete with collapsible stock and single-shot, semi-automatic fire. The MP5A4 utilized a fixed stock with a 3-round burst firing function while the MP5A5 was given a collapsing stock with burst fire mode. The MP5N was a specialized US Navy variant with Navy trigger group (showing fire selection through bullet symbols instead of the usual "SEF" text), collapsing stock and threaded sound suppressor support. The French Army received specialized MP5s as the "MP5F", featuring a collapsing stock and revised internals for their special ammunition requirements.
One of the most popular MP5 production models became the MP5K (K = Kurz for "Short") which took an already compact firearm and made it more so through use of a shorter barrel and forend and lacked a stock. The fire selector allowed for single- and full-automatic fire only and the front end of the weapon was supported through a rubber-encased vertical grip handle mounted just ahead of the magazine well. All other MP5 functions remained the same. The MP5K eventually produced its own sub-set of variants: The MP5KA1 was given a cleaner upper receiver with single-/full-auto firing function and more compact iron sights. The MP5KA4 featured a three-round burst fire capability while the MP5KA5 was the MP5KA1 though with three-round burst capability. The MP5K-N was a US Navy model with Navy trigger group and threaded suppressor support. The MP5K-PDW ("Personal Defense Weapon") was the MP5K-N with three-round burst support, forward vertical grip and hinged folding stock. The MP5/10 was a specialized form chambered for the 10mm Auto cartridge while the MP5/40 fired the .40 S&W cartridge. The MP5 was imported in civilian guise to the United States as the HK94 and another civilian offering became the SP89 intended for sport shooting and to conform to the 1989 Semi-Automatic Weapons Ban. European civilians had access to the T-94 ZSG (Zivile Sportgewehr) model.
One of the more identifiable MP5 production models was its silenced - or "SD" - form which, like the HKMP5K, produced its own sub-set of variants: the MP5SD1 was the initial model and lacked a stock though fitted with single-shot/full-auto fire capable and integral suppressor (as opposed to threaded). The MP5SD2 sported a full fixed stock with integral suppressor with single/full auto support. The MP5SD3 was given a collapsing stock and retained the built-in suppressor. The MP5SD4 lacked the stock but retained the suppressor and included a three-round burst fire mode. The MP5SD5 was a fixed stock version with suppressor and three-round burst capability. The MP5SD6 sported a collapsing stock with suppressor ad three-round burst fire. The MP5SD-N1 was an American Navy modification with collapsing stock and stainless steel suppressor, the latter developed by Knight's Armament Company. The MP5SD-N2 was similar though with a fixed full stock.
The HK MP5 eventually became the logical weapon of choice for most North American and and European special forces groups and police. It proved extremely successful as a close-quarters man-stopper and was utilized by the notable likes of the United States Navy SEALs, the German GSG9 and British SAS.
The HK53 was more or less the HK MP5 though chambered for the American 5.56x45mm rifle cartridge - though marketed as a variant of the full-length HK33 Assault Rifle.