3-inch gun M1918

The 3-inch gun M1917 was the United States Army's first dedicated anti-aircraft gun, entering service during World War I. Only a few were built, as the similar 3-inch gun M1918 on a mobile mount was considered more useful and was produced in large numbers. Development of the M1917 started in 1915, and as the name implies, took two years to enter service. The gun was essentially an unmodified 3-inch M1903 (76.2 mm L/55) coastal-defense gun barrel on a new fixed mount allowing it to be aimed to high elevations. A number were used during World War I on fixed mountings; 116 were completed by April 1919. Most of the weapons were deployed at United States Army Coast Artillery Corps seacoast forts after World War I. In the immediate post-war era it was developed as the 3-inch M2, using a removable barrel liner. In 1928 it was further improved in the 3-inch M4 by using a thicker removable liner that eased manufacturing. However, the M2 and M4 appear to have been produced in small quantities. The M1917, M2, and M4 remained in service through World War II. ==History of the 3-inch M1918==

{{Externalimage For mobile use the original coastal gun was too heavy, so a smaller version was developed as the 3-inch M1918. This weapon was based on the Driggs-Seabury 3-inch gun M1898, a smaller predecessor of the M1903. This weapon had a barrel 50 calibers long instead of 55 calibers, and a smaller breech ( instead of with a different cartridge (reportedly 76.2x585R instead of 76.2x690R) featuring the maximal propelling charge decreased from | to . The barrel of the M1918 was shortened to 40 calibers and a semi-automatic breech was added. ==Variants==

• 3-inch Gun M1917 – Original fixed-place anti-aircraft gun introduced in 1917, barrel based on 3-inch gun M1903. • M1918 – Mobile anti-aircraft gun using a barrel based on the 3-inch gun M1898 and a new mount. • M1 – Variant of the M1918 with a removable barrel liner. • M2 – Variant of the M1917 with a removable barrel liner. • M3 – Development of the M1918 with a removable barrel liner, but on a mobile mount. • M4 – Version of the M2 with a thicker liner for easier manufacturing. • M5 – Version of the T9 adapted for anti-tank use. • M6 – Version of the T9 as mounted in the 3-inch M5 gun motor carriage. • M7 – Version of the M5 for use on the M6 heavy tank and M10 tank destroyer ==Self-propelled mounts==

• Heavy Tank M6 (M7 gun in mount T49). • 3-inch Antiaircraft Gun Carriage T1 (Garford 7½ ton 6x4 truck chassis). • 3-inch gun motor carriage T1 / M5 (high-speed tractor M2 chassis, M6 gun). • 3-inch gun motor carriage T7 (trackless tank chassis). • 3-inch gun motor carriage T15 (Ford 4x4 / 6x6 truck chassis). • 3-inch gun motor carriage T20 (light tank M3 chassis). • 3-inch gun motor carriage T24 (medium tank M3 chassis, M3 gun). • 3-inch gun motor carriage T35 / M10 (M4 Sherman chassis, M7 gun in mount M5). • 3-inch gun motor carriage T40/M9 (medium tank M3 chassis, M1918 gun). • 3-inch gun motor carriage T50. • 3-inch gun motor carriage T55. • 3-inch gun motor carriage T56, T57 (light tank M3A3 chassis, M7 gun). ==Surviving examples==

The only known surviving example is located at the Fort Sill, Oklahoma, museum. ==See also==