5"/54 caliber Mark 45 gun

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“Mark 45” redirects here. For the torpedo, see Mark 45 torpedo.

General Characteristics

Designation:	Mark 45 - 5-inch/54-caliber lightweight gun
Date of design:	1968
Date in service:	Mark 45 Mod 0 - 1971 Mark 45 Mod 1 - 1980 Mark 45 Mod 2 - 1988
Mounting weight:	21.7 tons
Gun length oa:	29.5 ft (9 m)
Barrel length:	22.5 feet (6.86 m)
Rifling length:	19.1 feet (5.82 m)
Barrel life:	8,000 rounds
Caliber:	5 in (127 mm)
Maximum train:	170 degrees either side of centerline
Train rate:	30 degree/s
Max/min elevation:	65 / -15 degrees
Elevation rate:	20 degree/s
Rate Of fire:	16-20 rounds per minute automatic
Muzzle velocity:	2,650 ft/s (808 m/s) full service charge 1,500 ft/s (460 m/s) reduced charge for defilade fire or illumination rounds
Shell weight:	Variable depending on type; up to 70 lb (32 kg)
Magazine capacity:	Ticonderoga class: 600 rounds Arleigh Burke class: 680 rounds Other classes: 475 to 500 rounds
Range:	13 nautical miles (24 km)
Manufacturer:	BAE Systems Land and Armaments, Armament Systems Division

The 5 Inch/54-caliber (Mk 45) lightweight gun is a modern naval artillery gun mount consisting of a 5 inch (127 mm) L54 Mark 19 gun on the Mark 45 mount. It is designed to be used against surface warships, for anti-aircraft use and shore bombardment to support amphibious operations.

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 (below deck) by a three man crew (gun captain, panel operator, and ammunition loader) to keep the gun supplied with ammunition. An advanced version, the Mk 45 mod 4 lightweight gun, uses a longer barrel (62 caliber versus 54) for more complete propellant combustion, higher velocity and greater utility as a land attack weapon.

1 History
2 Variants
3 Use
4 References

[edit] History

Development started in the 1960s as a replacement for the 5 inch 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 US naval ships. While its rate of fire is lower than the British 4.5 inch (114 mm) gun, the heavier 5" projectile has better utility in attacking warships, and carries a larger bursting charge, which grants it greater per-shell effectiveness against aircraft.

[edit] Variants

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.

USS Cowpens (CG-63) fires its Mark 45

[edit] Use

In sustained firing operations (Mode III), the gun is manned by a three man crew all located below decks. These are a gun captain, a panel operator, and ammunition loader. 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).