4"/50 caliber gun

The 4"/50 caliber Mark 9 gun (spoken "four-inch-fifty-caliber") was the standard low-angle, quick-firing gun for United States destroyers through World War I and the 1920s. United States naval gun terminology indicates the gun fired a projectile 4 inches (10 cm) in diameter, and the barrel was 50 calibers long. (barrel length is 4" x 50 = 200" or 5 meters) [Fairfield 1921 p.156]

The gun weighed about 2.7 tonnes and used fixed ammunition (case and projectile handled as a single assembled unit) with a 14.5-pound (6.6 kg) charge of nitrocellulose propellant to give a 33-pound (15 kg) projectile a velocity of 2900 feet per second (884 m/s). Range was 9 miles (15 kilometers) at the maximum elevation of 20 degrees. [Campbell 1985 p.143]

Increasing awareness of the need for improved anti-aircraft protection encouraged mounting of dual purpose guns on destroyers beginning in the 1930s. The dual-purpose 5"/38 caliber gun became standard for United States destroyers constructed from the 1930s through World War II. United States destroyers built with 4"/50 caliber low-angle guns were rearmed with dual-purpose 3"/50 caliber guns. The 4"/50 caliber guns removed from destroyers were mounted on Defensively Equipped Merchant Ships like SS Stephen Hopkins. [Campbell 1985 p.143]

The 4"/50 caliber gun was mounted on:
* Caldwell class destroyers [Fahey 1939 p.14]
* Wickes class destroyers [Fahey 1939 p.14]
* Clemson class destroyers [Fahey 1939 p.14]
* Town class destroyers [Lenton&Colledge 1968 pp.90-92]
* United States S class submarines [Fahey 1939 p.18]
* the first seven Balao class submarines [Campbell 1985 p.143]
* USS Dolphin (SS-169) [Fahey 1939 p.18]
* rearmed submarines USS Salmon (SS-182) , USS Seadragon (SS-194), USS Gato (SS-212) and USS Robalo [Campbell 1985 p.143]

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