The MG4 is a belt-fed 5.56 mm light machine gun designed and developed by the German company Heckler & Koch. The weapon was developed in the late 1990s and was first seen publicly in September 2001. It has been selected to replace the 7.62 mm MG3 general-purpose machine gun in the Bundeswehr at the squad support level; it will complement the MG3 in other roles. The MG4 will also be the secondary armament of the new Puma infantry fighting vehicle. Overall, it is designed to be light, provide maximum safety to the user and function reliably under adverse conditions using a wide range of ammunition from different manufacturers, without the need to adjust the gas system. The machine gun was initially known as the MG43 prior to its adoption by the Bundeswehr.
The MG4 is an air-cooled, belt-fed gas-operated weapon with a positively locked rotary bolt and is somewhat similar in concept to the Belgian Minimi light machine gun. Firing in fully automatic or burst-fire mode. Safety mechanisms on the MG4 includes a manual safety incorporated into fire mode selector toggle; setting the fire selector lever on the "safe" position blocks the trigger mechanically and locks the bolt in the cocked position. When the bolt is not pulled back completely, accidental firing is prevented by an integral, automatic mechanism that prevents the bolt from traveling forward. In addition, the firing pin cannot reach the cartridge primer until the cartridge has been fully chambered.
In Project Reality, the MG4 is the main automatic rifleman weapon of the German Armed Forces (Bundeswehr) equipped with an optical scope or with a Zeiss Z-Point red dot sight.
- The MG4 is one of the few NATO automatic rifleman weapons that is not a variant of the Minimi.
- It's one of the few firearms that the iron sight is unusable, despite being clearly present in the weapon.