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Mark 42 5"/54 Caliber Gun
5 inch Mark 42 on USS Turner Joy (DD-951), front.jpg
5 inch/54 Mark 42 on USS Turner Joy (DD-951)
Type Naval gun
Place of origin United States
Service history
In service 1953 - present
Used by See users
Wars Vietnam war
Lebanese Civil War
Weight 60.4 long tons (61.4 t)
Length 9.652 m (31 ft 8.0 in)
Barrel length 6.858 m (270.0 in)
Rifling: 5.82 m (229 in)

Shell Conventional: 31.75 kg (70.0 lb)
Caliber 5 inches (127.0 mm)
Recoil 18.75 inches (476.2 mm)
Elevation • -15°/+85°
Maximum elevation rate: 25°/sec
Traverse • 150° from either side of centerline
Maximum traversing rate: 40°/sec
Rate of fire As built/designed: 40 rounds per minute automatic
Down-rated to 28 rounds per minute in 1968
Muzzle velocity 2,650 ft/s (807.7 m/s)
Maximum range • 25,909 yd (23,691.2 m) at +45° elevation
• 51,600 ft (15,727.7 m) at +85° elevation

The Mark 42 5"/54 caliber gun (127mm) is a naval gun (naval artillery) mount used by the United States Navy and other countries. It consisted of the Mark 18 gun and Mark 42 gun mount. United States naval gun terminology indicates the gun fires a projectile 5 inches (127.0 mm) in diameter, and the barrel is 54 calibers long (barrel length is 5" × 54 = 270" or 6.9 meters.)[1] In the 1950s a gun with more range and a faster rate of fire than the 5"/38 caliber gun used in World War II was needed. Because of this reason, the gun was created concurrently with the 3"/70 Mark 26 gun for different usages. The 5"/54 Mk 42 is an automatic, dual-purpose (air / surface target) gun mount. It is usually controlled remotely from the Mk 68 Gun Fire Control System, or locally from the mount at the One Man Control (OMC) station.[2]

The self-loading gun mount weighs about 60.4 long tons (61.4 t) including two drums under the mount holding 40 rounds of semi-fixed case type ammunition. The gun fires 31.75 kg (70.0 lb) projectiles at a velocity of 2,650 ft/s (807.7 m/s).[3] Maximum rate of fire is 40 rounds per minute.[4] Magazine capacity is 599 rounds per mount.[3] The Mark 42 mount originally was equipped for two on-mount gunners, one surface and one antiaircraft, but the antiaircraft gunner position was scrapped later on when the increasing speed of naval aircraft made manual aiming of antiaircraft weapons impractical. The Mark 45 lightweight (22.1 long tons (22.5 t))[5] gun mount began replacing the Mk 42 mount in 1971 for easier maintenance and improved reliability in new naval construction for the United States Navy.[6]

Two of the eight turrets of the carrier USS Ranger (CVA-61) firing, in 1961.


United States
United States Navy

Side profile of the 5-inch gun from HMAS Brisbane

Royal Australian Navy
Egyptian Navy
German Navy
Hellenic Navy
Japan Maritime Self-Defense Force
Mexican Navy
Spanish Navy
Republic of China Navy
Royal Thai Navy
  • Phutthayotfa Chulalok-class frigate (ex-USN Knox class frigates)
Turkish Navy

See also


  1. Fairfield(1921)p.156
  2. Seaman - Military manual for the Seaman rate
  3. 3.0 3.1 Bailey(January 1983)p.106
  4. O'Neil(March 1971)pp.48-49
  5. O'Neil, March 1971, pp. 48-49
  6. Cooney(1980)p.40
  • Bailey, Alfred D., Major USMC (January 1983). "The 16-incher: Big, Big Gun". United States Naval Institute Proceedings. 
  • Cooney, David M., RADM USN (1980). Ships, Aircraft and Weapons of the United States Navy (NAVSO P-3564). U.S. Government Printing Office. 
  • Fairfield, A.P. (1921). Naval Ordnance. The Lord Baltimore Press. 
  • O'Neil, William D., III, LCDR USNR (March 1971). "Gun Systems? For Air Defense?". United States Naval Institute Proceedings. 

External links

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