This anti-aircraft gun was removed from the battleship U.S.S. Missouri, where the official surrender of Imperial Japan took place on September 2, 1945, ending World War II. Bofors AB of Sweden developed the original autocannon design in 1936, and the United States Navy accepted a licensed 40mm/56 caliber variant produced by Chrysler in 1942. Capable of firing 120 rounds per minute of both armor piercing and high explosive shells, the weapon had a maximum range of 11,000 yards, though shell fuses purposely limited it to 4,500 yards to avoid friendly fire instances. Gun emplacements were often paired with Mark 51 directors that improved accuracy by computing range and trajectory, and a radar scope was also used for nighttime targeting. Together, these features helped make the Bofors one of the most effective medium anti-aircraft weapons of the war.
