Nkm wz.38 FK

The nkm wz. 38 FK (Polish military acronym meaning heaviest machine gun pattern 1938) was a 20 mm heavy machine gun (autocannon by modern terminology) produced in inter-war Poland. It was used both in anti-air and anti-tank role and was also adapted for tank use and mounted on some TKS tankettes. Mass-produced since 1938, it was used extensively during the Polish Defensive War of 1939.