MG-51 / MG-87

Around 1942, the Swiss Army sought a replacement for the MG 11 heavy machine gun and the Furrer M25 light machine gun, specifying a maximum cyclic rate of fire of 1,000 rounds per minute. Waffenfabrik Bern, SIG, and Hispano-Suiza participated in the competition. Waffenfabrik Bern based its development on the German MG 42, with early prototypes appearing around 1944. The final design, appearing in 1950, was similar to the MG 42 but featured more components produced by machining instead of stamping. To prevent locking timing induced short shot problems, the locking system was changed from roller locking to flapper locking.

The MG 51 is a short-recoil-operated, locked breech, air-cooled, automatic only, belt-fed weapon. It employs a locking system with a two-piece bolt and dual locking flaps in the front section of the bolt that engage cuts in a short barrel extension for rigid locking. Upon recoil, the flaps retract inward to unlock. A lever-type bolt accelerator is located in the receiver. The gun housing consists of a stamped steel barrel jacket permanently welded to a solid machined receiver. The barrel can be rapidly changed using a latch on the right side of the jacket. The belt feed system, similar to the MG 42, utilizes open-pocket steel belts with a two-stage pull, and feeds from the left. Ammunition boxes could hold up to 200 belted rounds, while 50-round belts for the mobile role can be loaded into drum-type containers clipped to the gun's side. Standard open iron sights are graduated from 100 to 2,000 meters in 100-meter increments, and feature a folding front sight. A 2.3x optical sight is also available for use up to 2,000 meters. A folding bipod is fitted for the light machine gun role, while a universal heavy tripod was developed for the medium machine gun role. The Flab mount allowed for use against aircraft up to approximately 800 meters. Early production guns had wooden furniture, replaced by polymer on more modern versions.

Variants include:

• The standard Mg 51

• The Mg 51/71, a version designed for vehicles such as the Mowag Eagle or Pz 68

• The Mg 51/80, created for fortifications

• The Pz Mg 87, a coaxial version for the Pz 87, featuring an electromagnetic trigger

Other Mg 51-based Pz Mg variants were utilized as coaxial or pintle-mounted machine guns on the Pz 55/57, Panzer 68, and Entp Pz 65 tanks. The Pz Mg 87 variant used on the Pz 87 "Leopard 2" tank incorporates an electromagnetic trigger and a switch to reduce the rate of fire by 50%, along with a mount designed to fit within the armor.

The MG 51 served as a primary infantry and vehicle machine gun for the Swiss Army. It was typically used in the medium machine gun role from its universal tripod for firing at ranges of 600 to 1,500 meters. In the light machine gun role up to 600 meters, it could fire short bursts of 6 rounds from its bipod or from the hip during mobile assaults. Fitted with the Flab mount, it was also used for frontal combat against aircraft up to a distance of about 800 meters. The MG 51 began to be gradually replaced in Swiss service after 2005 by the FN Minimi.

Users of the W+F MG-51 include Switzerland and Denmark. The Danish versions are chambered for .30-06 Springfield.