The Heckler & Koch MG5 (previously known as the HK121) is a general purpose machine gun manufactured by Heckler & Koch.
The weapon is intended as a replacement for the well proven Rheinmetall MG3. Fifteen pre-production units were order by the Bundeswehr, designated as the MG5, with 1215 units ordered initially. A total procurement of 12,733 units with a total production cost of about €200 million have been delayed due to accuracy concerns.
The weapon operates very similarly to the older Heckler & Koch MG4; gas-operated with a rotating bolt.