1.1-inch/75-caliber gun

Common card · No. 260084

The 1.1"/75 caliber gun was an American anti-aircraft weapon of World War II, used by the United States Navy. The name means that it had a bore diameter of 1.1 in (28 mm) and barrel caliber of 75 (1.1 inches × 75 = 82.5 in (2.1 m)). The gun was designed to replace the M2 Browning and four barrels were required to duplicate the rate of fire. The first shipboard installation, in 1939, was nicknamed the Chicago Piano. By 1941, these guns had been mounted on destroyers, cruisers, battleships, aircraft carriers, and some auxiliary ships. Nearly a thousand guns had been produced before production shifted to more reliable shipboard anti-aircraft machine guns in 1942. Quantities were minimal; one mount for a destroyer, two mounts for pre-1930s battleships, and four mounts for North Carolina–class and newer battleships. On at least some ships they were director-controlled. The gun was very unpopular with its crews; it was said that due to its tendency to jam, the only way to fire one was to position...

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