Design work for the 127-mm OTO Melara Compact 54-calibre gun started in 1965 as a joint venture by OTO Melara with the Italian government. The first prototype was completed in May 1969 and the gun was adopted as the main armament for new-build Italian navy frigates and destroyers. The loading, ammunition, feeding and firing sequences are controlled by one man in the ship's operations room using a console. Ready-use ammunition is held in three 22-round loading drums below deck under the mount. This allows a choice between three different ammunition types, the gun's operator choosing the round appropriate to the action. The three drums are automatically reloaded via two hoists that are manually replenished in the main magazine. A drum can be reloaded even whilst the gun is firing. The barrel itself is fitted with a muzzle brake. Apart from Italy the navies of Argentina, Canada, Iraq, Nigeria, Peru and Venezuela have guns of this type in service aboard frigates and destroyers.

Specification 12T-mm OTO Melara Compact Calibre: 127 mm (5 in)

No. of barrels: one Weight: 34 tons Elevation: - 15° to +85°

Muzzle velocity: 807 m (2, 648 ft) per second

Projectile weight: unknown

Total round weight: 32 kg (70.5 lb) Maximum rate of fire: 45 rpm Maximum effective ranges: surface fire 15 km (9.3 miles), and anti-aircraft fire 7 km (4.3 miles)