3"/50 caliber gun
From Wikipedia, the free encyclopedia
| 3 Inch / 50 Cal Gun (Mk 22) | |
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| Type | Deck Gun |
| Place of origin | United States |
| Service history | |
| Used by | US Navy |
| Specifications | |
| Weight | 7,500 lbs |
| Crew | 7 |
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| Shell | AA, AP, Illumination |
| Caliber | 50 |
| Elevation | -15 to 85 degrees |
| Rate of fire | 20 rpm |
| Muzzle velocity | 2,700 feet/sec |
| Maximum range | 14,600 yards |
| Sights | Peep-site and Optical telescope |
The 3"/50 caliber gun (Mark 22) was a semiautomatic dual purpose anti-aircraft and surface target weapon used by the U.S. Navy from the 1940's through the 1960's on a variety of combatant and transport ship classes with a power driven automatic loader that fired a fixed AA (Anti Aircraft) or HC (High Capacity) round consisting of a projectile and a cartridge case crimped to the projectile. The average weight of the round was 34 pounds. The projectiles weighed about 13 pounds including a burster charge of 0.81 pounds for the AA round and 1.27 pounds for the HC round. The initial velocity of the round was 2,700 feet/second with a maximum range of 13,100 yards at 45 degrees elevation and a ceiling of 27,300 feet at 85 degrees elevation. The gun could fire at a rate of 50 rounds/minute.
The 3" guns were fitted to both single and twin mountings. The single was to be exchanged for a twin 40-mm. mount and the twin for a quadruple 40-mm. mount. Although intended as a one-for-one replacement for the 40-mm. mounts, the final version of the new 3-inch mounts was heavier than expected, and on most ships the mounts could be replaced only on a two-for-three basis. The mounts were of the dual purpose, open-base-ring type. The right and left gun assemblies were identical in the twin mounts. The mounts used a common power drive that could train at a rate of 30 degrees/second and elevate from 15 degrees to 85 degrees at a rate of 24 degrees/second.
The gun was used in single or dual open mounts, designed to replace dual and quad 40 mm antiaircraft guns, respectively. It could fire a 13-pound projectile 14,600 yards in a surface role, and to 29,800 feet as an antiaircraft gun. The rate of fire was about 20 rounds per minute per barrel, which was good against slower planes, but not effective against faster ones such as jets.
The weapon was considered ineffective against surface targets. However, with World War II improvements in fuzing and fire control, a dual 3"/50 mount was considered as effective as a quad Bofors 40mm gun in the anti-aircraft role. Destroyers that were modernized during the Fleet Rehabilitation and Modernization (FRAM) program of the 1960's had their 3-inch guns removed, but others retained them.
