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5"/54 caliber Mark 45 gun

Mark 45 5-inch/54-caliber lightweight gun
The latest version, a 5"/62 caliber Mark 45 Mod 4 test firing on USS Forrest Sherman (DDG 98) in 2007
Type Naval gun
Place of origin United States
Service history
In service
  • Mod 0: 1971[1]
  • Mod 1: 1980[1]
  • Mod 2: 1988[1]
  • Mod 4: 2000[2]
Used by See Operators
Production history
Designed 1968[1]
Manufacturer United Defense[1] (now BAE Systems Land & Armaments)
Produced 1971[1]
  • Mod 2: 21,691 kg (47,820.5 lb)[1]
  • Mod 4: 28,924 kg (63,766.5 lb)[1]
  • Mod 2: 8.992 m (29 ft 6.0 in)[3]
  • Mod 4: 10.008 m (32 ft 10.0 in)[2]
Barrel length
  • Mod 2: 6.858 m (270.0 in)[3]
    Rifling: 5.82 m (229 in)[3]
    8,000 rounds (barrel life)[3]
  • Mod 4: 7.874 m (310.0 in)[2]
    Rifling: 6.836 m (269.1 in)[2]
    7,000 rounds (barrel life)[2]

Shell Conventional: 31.75 kg (70.0 lb)[1]
Caliber 5.0 inches (127.0 mm)
Barrels Single barrel (progressive RH parabolic twist)
  • −15° – +65°[3]
    Maximum elevation rate: 20°/sec[3]
  • ±170° from centerline[3]
    Maximum traversing rate: 30°/sec[3]
Rate of fire 16–20 rounds per minute automatic[4]
Muzzle velocity
  • Mod 2: 2,500 ft/s (762.0 m/s)[1]
  • Mod 4: 2,650 ft/s (807.7 m/s)[1]
  • 1,500 ft/s (457.2 m/s) reduced charge for defilade fire or illumination rounds
Effective firing range 13 nmi (24.1 km)[4]
Feed system 600 rounds (Ticonderoga class)
680 rounds (Arleigh Burke class)
475–500 rounds (Other classes)

The 5-Inch/54-caliber (Mk 45) lightweight gun is a modern U.S. naval artillery gun mount consisting of a 5-inch (130-millimetre) L54 Mark 19 gun on the Mark 45 mount.[1] Originally designed and built by United Defense, it is now manufactured by BAE Systems Land & Armaments after the former was acquired. The latest 5-inch/62-caliber version consists of a longer barrel L62 Mark 36 gun fitted on the same Mark 45 mount.[1] The gun is designed for use against surface warships, anti-aircraft and shore bombardment to support amphibious operations.[1]

The gun mount features an automatic loader with a capacity of 20 rounds. These can be fired under full automatic control, taking a little over a minute to exhaust those rounds at maximum fire rate. For sustained use, the gun mount would be occupied by a six-man crew (gun captain, panel operator, and four ammunition loaders) below deck to keep the gun continuously supplied with ammunition.


  • History 1
  • Variants 2
    • Guided shell 2.1
  • Operators 3
    • Current operators 3.1
  • See also 4
  • References 5
  • External links 6


Development started in the 1960s as a replacement for the 5"/54 caliber Mark 42 gun system with a new, lighter, and easier to maintain gun mounting. In USN use, the Mark 45 is used with either the Mk 86 Gun Fire Control System or the Mk 160 Gun Computing System. Since before World War II, 5 inch has been the standard gun caliber for U.S. Naval ships. Its rate of fire is lower than the British 4.5-inch (113 mm) gun, but it fires a heavier 5" shell which carries a larger burst charge that increases its per-shell effectiveness against aircraft.


  • Mod 0: used mechanical fuze setter. Two-piece rifled construction, with replaceable liner
  • Mod 1: electronic fuze setter replaces the mechanical one. Made with a unitary construction barrel, which has a life span approximately twice that of the Mark 42 gun.
  • Mod 2: export version of Mod 1, but now used in the US Navy
  • Mod 3: same gun with a new control system; never put into production
  • Mod 4: longer 62-caliber barrel (versus Mod 1 and 2's 54 caliber) for more complete propellant combustion, higher velocity, range increased to 20 nautical miles (37 kilometres; 23 miles)[5] and thus more utility for land attack.
Special note

In sustained firing operations (Mode III), the gun is manned by a six-man crew all located below decks. These are a gun captain, a panel operator, and four ammunition loaders. In fully automatic non-sustained firing operations (Mode IV), the gun can be fired without any personnel inside the mount. However, sustained fire is limited to the capacity of the automatic loader (20 rounds). This means that there will be no one at control panel for the gun to safe the weapon when having to fall back to verbal cease fire to the gun crew.

Guided shell

On 9 May 2014, the U.S. Navy released a request for information (RFI) for a guided 5-inch round that could be fired from Mark 45 guns on Navy destroyers and cruisers. The thinking is that if the technology worked in the 155 mm (6.1 in) Long Range Land Attack Projectile (LRLAP) for the Advanced Gun System on Zumwalt-class destroyers, it can be applied to a five-inch mount. This RFI comes six years after the cancellation of the Raytheon Extended Range Guided Munition. The shell must have at least double the range of unguided shells for missions including Naval Surface Fire Support (NSFS)/Land Attack, and increasing Anti-Surface Warfare (ASuW) capabilities against Fast Attack Craft (FAC) and Fast In-Shore Attack Craft (FIAC); the main purpose is to destroy incoming small boats at a greater range with a proximity fuse airburst blast fragmentation warhead to spray shrapnel over swarms. Expected submissions include the BAE Systems Multi Service–Standard Guided Projectile (MS-SGP), Raytheon Excalibur N5, and OTO Melara Vulcano guided long-range projectile.[6][7]

Naval Sea Systems Command is also looking to fire a version of the hyper velocity projectile (HVP) developed for Navy electromagnetic railguns from conventional 5-inch deck guns. The shell would travel at Mach 3, slower than from the railgun, but still faster than a regular unguided 5-inch shell. Using the HVP could give existing destroyers and cruisers better ability to engage land, air, and missile threats and allow more time to refine the railgun. The HVP would be a cheaper solution to intercepting incoming missiles than a missile interceptor costing hundreds of thousands of dollars. Converting the HVP to fire from conventional guns is not yet a program of record.[8]


Map with 5"/54 caliber Mark 45 operators in blue
Mark 45 gun aboard Australian Anzac-class frigate HMAS Arunta (FFH 151)
5"/54 Mark 45 Mod 2 firing on board the Arleigh Burke-class destroyer USS Benfold (DDG-65) in 1997
Loading a 70-pound 5-inch round in the below-deck gun mount aboard USS Cole (DDG 67)

Current operators

Royal Australian Navy
Royal Danish Navy
Hellenic Navy
Japan Maritime Self-Defense Force
 Republic of Korea
Republic of Korea Navy
 New Zealand
Royal New Zealand Navy
Spanish Navy
Republic of China Navy
Royal Thai Navy
Turkish Navy
 United States
United States Navy
Active service ships:

See also


  1. ^ a b c d e f g h i j k l m n Norman Polmar, pp. 492-493
  2. ^ a b c d e "United States of America 5"/54 (12.7 cm) Mark 45 Mod 4". NavWeaps.Com. 18 April 2010. Retrieved 24 October 2010. 
  3. ^ a b c d e f g h "United States of America 5"/54 (12.7 cm) Mark 45 Mods 0 - 2". NavWeaps.Com. 18 September 2007. Retrieved 24 October 2010. 
  4. ^ a b c d e "The US Navy Fact File: 5-inch Mark 45 54-caliber lightweight gun". United States Navy. 20 February 2009. Archived from the original on 5 December 2010. Retrieved 24 October 2010. 
  5. ^ "5-inch 62-Caliber Mk 45 Mod 4 Naval Gun System" (PDF). Brochure. BAE Systems. Archived from the original (PDF) on 2012-04-25. Retrieved 5 October 2011. 
  6. ^ Navy Taking a Second Look at A Five-Inch Guided Round -, 3 June 2014
  7. ^ Navy seeks guided deck-gun shell -, 4 June 2014
  8. ^ Navy Researching Firing Mach 3 Guided Round from Standard Deck Guns -, 1 June 2015
  • Norman, Polmar (2005). The Naval Institute guide to the ships and aircraft of the U.S. fleet (18th ed.). Annapolis, MD: Naval Institute Press. pp. 492–493.  

External links

  • US Navy Fact File - 5"/54 caliber Mark 45 gun
  • BAE Systems: Mk 45 Mod 4 Naval Gun System
  • BAE Systems: Mk 45 Naval Gun Overhaul and Upgrade
  • NavWeaps.Com: 5"/54 (12.7 cm) Mark 45 Mods 0 - 2
  • NavWeaps.Com: 5"/54 (12.7 cm) Mark 45 Mods 4
  • FAS: Gunner officer information sheet
  • BAE Systems' computer animation and video of the Mk 45 Mod 4 gun on YouTube
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