The HK21E is a submachine gun using a roller locked bolt and firing a 7.62 Ã— 51 mm caliber round.
The weapon has belt-feeding capabilities and handles the role of a squad automatc weapon. Most variants or versions of the HK21E had three-round burst trigger groups. The HK21E started as its predecessor the HK21. The weapon was a simple machine gun utilizing the same caliber rounds. Then came the HK21A1, which showcased some other minor modifications. The E in HK21E stands for Export. The weapon was fine tuned until it fit American import requirements before it was imported.