90 mm gun M1/M2/M3

The 90 mm gun M1/M2/M3 was an American heavy anti-aircraft and anti-tank gun, functionally comparable to the German 8.8 cm Flak 18, that served as the primary heavy anti-aircraft weapon of the United States Army from the late 1930s through the 1940s. The United States Army contracted its development on June 9, 1938, and the resulting prototype, designated T2, was standardized as the M1 on March 21, 1940, with the improved M1A1 variant entering service in late 1940. The gun had a 3.5 inch (90 millimeter) bore with a 50 caliber barrel roughly 15 feet long, capable of firing shells to a horizontal range of 62,474 feet or a maximum altitude of 43,500 feet. About 30 contractors built more than 140,000 units of the M1, M2, and M1A1 variants between 1940 and 1945, and the gun remained in active service from 1938 to 1960, serving through the Second World War and the Korean War before being replaced by surface to air missiles. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/