HK MG5

Heckler & Koch initiated development of the general-purpose machine gun, originally designated as the HK121, shortly after developing the MG4 light machine gun. The manufacturer publicly presented a prototype of the HK121 in July 2010 in Hammelburg. Designed as a modular weapon system to replace the MG3 machine gun in German service, the firearm underwent testing and evaluation by the German military starting in June 2013. The weapon officially entered German service in 2015. In 2024, the manufacturer introduced the HK421, a lightweight derivative designed for specialized infantry applications.

The firearm utilizes a long-stroke gas piston operating system with a conventional rotary bolt action firing from an open bolt. The locking, feed, and trigger mechanisms are derived from the MG4, but the receiver is constructed from two steel receiver shell castings and a connection block joined by a patented process. It features a cold-hammered, chrome-lined quick-change barrel equipped with a heat shield and a carrying handle that allows barrel replacement without heat protection. An ambidextrous safety, a field-adjustable folding polymer buttstock, and a visible and tactile loaded chamber indicator are integrated into the design. A three-position adjustable gas port allows the operator to select the cyclic rate of fire or adjust for cartridge variations and fouling using a cartridge base. Ammunition feeds from the left side using disintegrating metal link belts via a belt drum, ammunition pouches, or belt boxes, employing a two-step direct push-through pawl mechanism. Sighting systems include adjustable iron sights or optical and night-vision sights mounted on accessory rails, with the German military utilizing a day optic combined with a red dot.

The German military adopted the firearm in 2015 to replace the MG3, utilizing a green-brown surface finish. The weapon is fielded in several variants: the MG5 Universal, the MG5 A2 Infantry variant, the MG5 S Special Forces variant, and the MG5 A1 Mounted variant. The MG5 A1 is integrated into vehicle mountings and remote weapon stations, including those used by the German Federal Police. Outside of Germany, the weapon is in service with the Albanian Land Force, the Chilean Marine Corps, the Indonesian Navy's Kopaska and Taifib units, the Malaysian Maritime Enforcement Agency, the Portuguese Air Force, the Spanish Army's Special Operations Command, and the armed forces of Ukraine.