| 4"/50 caliber naval gun | |
|---|---|
The gun from USS Ward which fired the first American shot of World War II at Pearl Harbor on 7 December 1941 |
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| Type | Naval gun |
| Service history | |
| In service | 1914 - 1945 |
| Used by | United States United Kingdom Canada |
| Wars | World War I World War II |
| Production history | |
| Designed | 1910 |
| Variants | Mk 7, 8, 9 and 10 |
| Specifications | |
| Weight | 5,450 pounds (2,470 kg) |
| Length | 206.5 inches (5.25 m) |
| Barrel length | 200 inches (5 m) bore (50 calibres) |
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| Shell | 33 pounds (15 kg)[1] |
| Calibre | 4 inches (100 mm) |
| Elevation | -15 to 20 degrees |
| Traverse | -150 to 150 degrees |
| Rate of fire | 8-9 rpm |
| Muzzle velocity | 2,900 feet per second (880 m/s)[1] |
| Maximum range | 15,920 yards (14,560 m)[1] |
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 inch x 50 = 200 inches or 5 meters).[2]
Contents |
The built-up gun with a tube, full-length jacket, and side swing Welin breech block with Smith-Asbury mechanism weighed about 2.7 tons. Fixed ammunition (case and projectile handled as a single assembled unit) with a 14.5-pound (6.6 kg) charge of smokeless powder to gave a 33-pound (15 kg) projectile a velocity of 2,900 feet per second (880 m/s). Range was 9 miles (14 km) at the maximum elevation of 20 degrees. Useful life expectancy was 500 effective full charges (EFC) per barrel.[1]
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.[1]
The 4"/50 caliber gun was mounted on:
Many Mark 9 guns were supplied to the United Kingdom during World War II as part of Lend-lease, both individually and on naval and merchant ships[6].