vz. 52/57

The light machine gun was developed in Czechoslovakia after the Second World War for the Czechoslovak Armed Forces. Designed by Václav Holek in the 1950s, the weapon was initially designated as the ZB 501. Manufacturing of the firearm was conducted by Zbrojovka Brno.

The firearm operates on a gas-operated system utilizing a tilting bolt that locks into the roof of the receiver. The overall action of the weapon is based on the Czechoslovak ZB-26 light machine gun. It features an integral bipod, interchangeable barrels, and iron sights. The feed system uses a compact and light lever-type mechanism based on the ZB-53 machine gun. This system accepts metallic belts or detachable box magazines interchangeably without requiring modification.

The weapon was in service with Czechoslovak forces from 1952 until 1964. In the mid-1950s, designer Jaroslav Myslík converted the weapon to fire the standard Warsaw Pact cartridge, creating the vz. 52/57 variant. Both models were replaced in Czechoslovak service between 1963 and 1964 by the Universal Machine Gun Model 1959, also designated as the Uk vz. 59. The firearm was used by military and paramilitary forces in Algeria, Angola, Biafra, Chad, Cuba, Egypt, Ethiopia, Grenada, Guinea, and Mozambique. It was deployed in conflicts including the Bay of Pigs Invasion, the Escambray Rebellion, the Nigerian Civil War, the Portuguese Colonial War, the Ethiopian Civil War, and the United States invasion of Grenada. In Cuba, the weapon was placed in the inventory of the Territorial Troops Militia. During the Bay of Pigs Invasion, operators reported that the ammunition belts were prone to failure, leading to a field preference for magazine feed over belt feed.