Manufactured by OTO-Melara, these weapons have a higher rate of fire and a greater maximum elevation than their rough equivalent, the USA 5"/54 (12.7 cm) Mark 45. Both use USN standard semi-fixed ammunition including surface, air, pyrotechnic and chaff rounds. Mounting reaction time is five seconds from target designation. The reloading, feeding and firing sequence is controlled by a central console which is operated by a single crewmember.

The Compact is intended for use on frigate and destroyer type warships. This mounting uses a water-cooled barrel mounted in a water-tight fiberglass gunhouse and has 66 ready-to-fire rounds in three drums located just below the gun house. Each drum can hold a different ammunition type and each can be independently selected. A central elevator hoists the ammunition and delivers it to two oscillating arms which move the rounds into the loading trays. The drums are automatically reloaded via two hoists which are manually loaded in the lower magazine. Reloading can take place while the gun is firing. As an option, this mounting can be fitted with a stabilized line of sight local control system.

The LW (for "Light Weight") is a simpler version intended for smaller ships such as corvettes. This mounting uses selectable dual ammunition feed and modular magazines with a minimum of twenty ready rounds. Three modular automatic feeding magazines are used, one for propelling charges and two for projectiles. This permits this mounting to fire two different and immediately selectable types of ammunition. The magazines can be reloaded while the gun is firing. Projectiles and propelling charges are hoisted separately to the gun level from below-deck feeding magazines. There is a composition station below the gun where the next round to be fired is selected just before it is taken up by the gun automatic loading system.

Both mountings use a water-cooled barrel, normally using sea water, but requiring fresh water for flushing after firing.

An interesting new munition for these guns is being developed by OTO-Melara. Called "Vulcano," this is a fin-stabilized, sub-caliber, extended range projectile which does not use rocket boost. Additional details are available in the ammunition section on the 127 mm/64 datapage.

Gun Characteristics

Designation 127 mm/54 (5") Compact
127 mm/54 (5") LW
Ship Class Used On Compact:
  • Italian: Animoso, Audace, Maestrale and Lupo classes
  • Argentina: MEKO 360 class
  • Japan: Kongo class
  • Korea: KD-1 class
  • Netherlands: De zeven Provincien class
  • Nigeria: MEKO 360 class
Date Of Design About 1965
Date In Service Compact: 1968
LW: 1985
Gun Weight N/A
Gun Length oa N/A
Bore Length 270.0 in (6.858 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire Compact: 40 rounds per minute
LW: 40 rounds per minute


Type Separate
Projectile Types and Weights 1 Mark 80 HE-PD 2: 67.6 lbs. (30.7 kg)
Mark 91 Illum-MT 2: 63.9 lbs. (29.0 kg)
Mark 116 HE-VT 2: 69.7 lbs. (31.6 kg)
Mark 127 HE-CVT 2: 68.6 lbs. (31.1 kg)
Mark 156 HE-IR 2: 69.0 lbs. (31.3 kg)
Bursting Charge N/A
Projectile Length Mark 80: 26 in (66 cm)
Mark 91: 26.1 in (66.3 cm)
Mark 116: 26 in (66 cm)
Mark 127: 26 in (66 cm)
Mark 156: 26 in (66 cm)
Propellant Charge Mark 67: 18.25 lbs. (8.3 kg)
Cartridge weighs 38.9 lbs. (17.6 kg) filled
Muzzle Velocity 2,650 fps (808 mps)
Mark 91, only: 2,700 fps (823 mps)
Working Pressure 18.5 tons/in2 (2,758 kg/cm2)
Approximate Barrel Life 7,000 rounds
Ammunition stowage per gun Compact ready-use: 66 rounds
LW ready-use: 20 to 40 rounds
Magazine: About 500 - 600 rounds

All projectiles have a 0.5 caliber boat-tail. See also the 127 mm/64 for the Vulcano round.

1 This weapon can use USN standard 5"/54 (12.7 cm) ammunition. The ones listed above are meant to be representational but by no means is this a complete listing.

2 HE-PD: High Explosive, Point Detonating Fuze; Illum-MT: Illumination, Mechanical Time Fuze; HE-VT: High Explosive, Variable Time Fuze; HE-CVT: High Explosive, Controlled Variable Time Fuze.


Elevation With most Projectiles using Mark 67 cartridge
Range @ 47 degrees 25,290 yards (23,130 m)
Effective Range 16,400 yards (15,000 m)
AA Range @ 83 degrees 23,000 feet (7,000 m)
Illumination 18,085 yards (16,540 m)

Illumination rounds are automatically timed to ignite at an altitude of 1,050 feet (320 m) over the target area.

Mount/Turret Data

Designation Single Mountings
Weight Compact: 82,670 lbs. (37,500 kg)
LW: 48,500 lbs. (22,000 kg)
Elevation Compact: -15 / +83 degrees
LW: -15 / +70 degrees
Elevation Rate Compact:
  • 30 degrees per second
  • Acceleration: 40 degrees per second2
  • 30 degrees per second
  • Acceleration: 40 degrees per second2
Train Compact: +165 / -165 degrees
LW: +180 / -180 degrees
Train Rate Compact:
  • 40 degrees per second
  • Acceleration: 45 degrees per second2
  • 36 degrees per second
  • Acceleration: 50 degrees per second2
Gun recoil N/A

The Compact uses electric servos for training and elevation, and requires 440V, 3-phase, 60 Hz (275 kVA +20% max. peak power for 0.4 sec). Reloading of the loader drums is performed by 4 to 8 handlers in the ship's ammunition magazine. Drums can be reloaded while the gun is firing. Ammunition flow is reversible so that rounds can be automatically unloaded.

The LW uses hydraulically operated feeding and loading systems. Servo systems are electric with plug-in modular electronics. This mounting requires 440V, 3-phase, 60 Hz <180 kVA for the main circuit and 115V, 1-phase, 400 Hz, 300 VA, for the servo and synchro network. Drums can be reloaded while the gun is firing. Ammunition flow is reversible so that rounds can be automatically unloaded.

Additional Pictures


Data from:

  • "Jane's Pocket Book 9: Naval Armament" edited by Denis Archer
  • "The Naval Institute Guide to World Naval Weapon Systems 1991/92" and "1994 Update" both by Norman Friedman
  • "The US Navy's Mk 45 Gun" article by Antony Preston in "Warship Volume VII"

Press releases:

NAVSEA 5-inch Gun Ammunition Fact Sheets

Special help by Leo Fischer

Page History

17 April 2008 - Benchmark

18 March 2009 - Added link to 127 mm/64 for Vulcano information

14 December 2012 - Added photograph of front view of LW mounting