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Mark 45 5-inch/54-caliber lightweight gun
US Navy 070111-N-4515N-509 Guided missile destroyer USS Forest Sherman (DDG 98) test fires its five-inch gun on the bow of the ship during training.jpg
The latest version, a 5"/62 caliber Mark 45 Mod 4 firing
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 users
Production history
Designed 1968[1]
Manufacturer United Defense[1] (now BAE Systems Land & Armaments)
Produced 1971[1]
Weight • Mod 2: 21,691 kg (47,820.5 lb)[1]
• Mod 4: 28,924 kg (63,766.5 lb)[1]
Length • 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)
Elevation • -15°/+65°[3]
Maximum elevation rate: 20°/sec[3]
Traverse • ±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 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 (127 mm) 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 consist 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.


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" 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, greater range at +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 save the weapon when having to fall back to verbal cease fire to the gun crew.


Mark 45 gun aboard HMAS Arunta (FFH 151)

Royal Australian Navy
Flag of Denmark.svg Denmark
Royal Danish Navy
Hellenic Navy
Japan Maritime Self-Defense Force
 Republic of Korea
Republic of Korea Navy
 New Zealand
Royal New Zealand Navy: Mod 2
Spanish Navy
Republic of China Navy
Royal Thai Navy
Turkish Navy

5"/54 Mark 45 Mod 2 firing

Loading a round aboard USS Cole (DDG 67).

United States
United States Navy
Active service ships:

See also


  • 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. ISBN 978-1-59114-685-8. 

External links