Nkm wz. 38 FK
The nkm acronym stands for Polish: najcięższy karabin maszynowy, literally the heaviest machine gun (i.e. heavier than standard contemporary heavy machine guns using standard rifle cartridges such as the 7.92 Mauser, .303 British or 7.62×54mmR).In this case the FK stood for Fabryka Karabinów, the Warsaw-based state-owned rifle factory.In early 1930s the Polish Army was looking for a modern anti-tank and anti-air weapon to replace outdated World War I equipment still in use.In 1931 heavy machine guns made by Hotchkiss, Solothurn and Oerlikon were tested, but were found unsuitable for Polish needs.In 1937 another commission was sent abroad to test the newly designed weapons of 20mm calibre by Oerlikon, Madsen and Hispano-Suiza.Engineer Bolesław Jurek of Warsaw-based Fabryka Karabinów company became the lead designer.It is mounted in the tank with a spherical yoke with an armored cover developed by Napiórkowski and Miniewski.As an anti-tank and anti-air weapon, the gun was to be used extensively: 8 pieces in AA configuration for every infantry division.