The MG21 is a general purpose light machine gun designed and manufactured by Heckler & Koch, the same manufacturers as that of the G36 assault rifle. The MG21 is designed after that of the venerable G3 automatic rifle, and is belt fed, chambered for the powerful 7.62mmx51mm NATO round and 5.56mmx45mm NATO round. It is currently in use by many Latin America, Asian, and African countries. Although it's official designation is HK21, it has other designations, and is designated the "MG21" in the Mexican military. The MG21 is operated by a delayed blowback system, using a two piece breech plate/delay rollers, closed bolt, and fluted chamber to feed disintegrating belts of ammunition at a cyclic rate of 900 RPM.