The MG3 is a machine gun of German origin. The MG3 is a designation for various machine guns developed when Germany entered NATO. It basically is a conversion of the MG42 machine gun which was widely used by Nazi Germany during World War 2. Besides the Belgian MAG the MG3 was the most common Western machine gun during the Cold War.

The MG3 essentially is a conversion of the MG42 to 7.62x51mm NATO. Early versions were simply conversions but later versions feature a multitude of minor upgrades in various areas. The MG3 retains the short recoil operation and roller locking mechanism. It is belt fed only and feeds from left to right. The square slotted forearm is open on the right to allow the quick change barrel to be removed. The MG3 can be used from the attached bipod, from a tripod and as a pintle mounted or coaxial machine gun.

The MG3 fires the 7.62x51mm NATO round from 50 round DM1 continuous belts or M13 or DM6 linked belts, mostly of 120 round length. The cyclic rate of fire is about 1.200 rpm. This results in a high ammunition consumption and rapid overheating. The barrel should be changed every 150 rounds fired in rapid succession. The MG1A2 and MG42/59 versions have a lower rate of fire of 900 rpm. The maximum effective range is 600 m from the bipod and 1 km when used from a tripod. The slant range is much longer.

The first user of the MG3 family was the German military, who adopted the MG3 for infantry, flexible and coaxial use. Various European nations adopted versions of the MG3 and produced them under license. The MG3 was also widely exported to Asia, the Middle East and Africa. The MG3 remains in use today, but in the infantry role it has often been replaced by light machine guns.