The basic action of the machine gun, which received the company designation HK 21, was similar to that of the G3 rifle. The HK 21 fired from a closed bolt (not that big issue since its heavy barrel was really quick-detachable) and, unlike most machine guns, its belt feeding module was located below the receiver. Variants: HK11E automatic rifle (magazine fed, 7.62 mm) HK13E automatic rifle (magazine fed, 5.56 mm) HK21E general purpose machine gun (belt feed, 7.62 mm) HK23E light machine gun (belt-fed, 5.56 mm). The "E" stands for "Export" model.
