4-inch/50-caliber gun

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
Type	Naval gun
Service history
In service	1913 - 1945
Used by	United States Navy Royal Navy Royal Canadian Navy Soviet Navy
Wars	World War I, World War II
Production history
Designed	1910
Variants	Mk 7, 8, 9 and 10
Specifications
Mass	5,450 pounds (2,470 kg)
Length	206.5 inches (5.25 m)
Barrel length	200 inches (5 m) bore (50 calibres)
Shell	33 pounds (15 kg)
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)
Maximum firing range	15,920 yards (14,560 m)

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. It was also the standard deck gun on S-class submarines, and was used to rearm numerous submarines built with 3" guns early in World War II. 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).

Description

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 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.

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 of the British Merchant Navy and United States Merchant Marine like SS Stephen Hopkins. As S-boats were transferred from combat patrols to training duties from mid-1942 through 1943, their 4-inch guns were removed and used to re-equip front-line submarines built with 3"/50 caliber guns.

US Navy service

The 4"/50 caliber gun was mounted on:

• Template:Sclass-s
• Template:Sclass-s
• Template:Sclass-s
• Template:Sclass-s
• Template:Sclass-s
• Template:Sclass-s
• Template:Sclass-s
• United States S-class submarines
• the first seven Template:Sclass-s
• USS Dolphin (SS-169)
• numerous rearmed submarines including USS Salmon (SS-182), USS Seadragon (SS-194), USS Gato (SS-212), USS Silversides (SS-236) and USS Robalo (SS-273)

UK service

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. Caldwell, Wickes, and Clemson-class destroyers transferred under the Destroyers for Bases Agreement became British and Canadian Template:Sclass2-s.

See also

• List of naval guns

Weapons of comparable role, performance and era

• BL 4 inch naval gun Mk VII British equivalent

References

• Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4.
• Fahey, James C. (1939). The Ships and Aircraft of the U.S. Fleet, War Edition. Ships and Aircraft.
• Fairfield, A.P. (1921). Naval Ordnance. The Lord Baltimore Press.
• Gardiner, Robert and Gray, Randal, Conway's All the World's Fighting Ships 1906-1921 Conway Maritime Press, 1985. ISBN 0-85177-245-5.
• Lenton, H.T.; Colledge, J.J. (1968). British and Dominion Warships of World War II. Doubleday and Company.

External links

• DiGiulian, Tony, United States of America 4"/50 (10.2 cm) Marks 7, 8, 9 and 10 at Navweaps.com