The history of Heckler & Koch began during the postwar period when three engineers, Theodor Koch, Edmund Hecklers, and Alex Seidel jointly opened an engineering office in 1950 under the name Heckler & Koch GmbH. In 1956 Heckler & Koch produced the G3 assault rifle which was a milestone in weapon development. The G3 was the standard issue assault rifle for all German forces by the Bundeswehr of the Federal Republic of Germany. In the mid-1960s, Heckler & Koch gained international prominence with the design and the manufacture of the 9mm MP5, soon to become the world's most popular submachine gun, embraced by special operations forces worldwide. A variety of models have been added over the past thirty years but the MP5 remains the pre-eminent arm of its class.

Now the MP5, along with the MP7 and USP are available in air soft models and the P30 and USP are available in air gun models offered by Umarex USA.

UMAREX holds the worldwide exclusive HK-trademark and exterior design copy license for use with UMAREX products, granted by HK, Inc., U.S.A.