The German firm Heckler & Koch (H&K) was founded in 1949 by Alex Seidel, Edmund Heckler and Theodor Koch. The company was established in the old Mauser arms factory in Oberndorf. This had been emptied by the French after WWII as provisional compensation for war damage they had suffered. As the German Army was being built up in the early 1950s, the company received a contract to manufacture the G3 automatic army rifle in .308 Winchester caliber. The H&K G3 is based on the Spanish CETME rifle which was in turn based on a Mauser design. The CETME design was then modified to German requirements with the help of the development department of Rheinmetall resulting in the G3 army rifle. H&K was one of the first arms manufacturers to use a polygonal barrel profile. This type of barrel does not have any gooves and lands, but a polygonal inside which allows for a certain rotation ensuring that the bullet rotates. Many of H&Ks innovations from military arms have made their way into the sport and hunting weapons. They include the aforementioned polygonal rifling, the G3 roller locking system, and military rotating diopter sights.
In addition to the ubiquitous MP-5 submachine gun, H&K also developed a small series of specialized rifles for sharpshooting. H&K is also the first company to produce a polymer framed gun. 1970's HK VP-70 predated Gaston Glock's famed Glock 17 by over a decade. In the mid-1980s H&K developed a special army rifle, the G11, for ammunition without cartridge cases. After the loss of several government contracts financial concerns began to plague H&K, a particularly severe blow was the US Armed Forces choosing the Beretta M9 over the P7M13 for the issued sidearm. The G11 project also hit a wall when interest waned. In March of 1991, H&K was purchased by the British Royal Ordnance. In 1995, the firm was taken over by the German Wischo concern.
The USP pistol that H&K had developed around this time began to gain interest. The United States Special Operations Command chose the USP-based SOCOM pistol as their special ops sidearm. It is known as the MK23 SOCOM. In 1997, H&K introduced a new rifle design called the G36 in assault rifle, light sub-machine gun, and carbine form. Unlike the G3 design, which had been H&K's bread and butter, the G36 abandons the roller locking system for a rotation locking system.