135 mm/45 Italian naval gun

The Cannone da 135/45 OTO 1937 was a 135 mm (5.3 in) 45-caliber naval gun built for the Regia Marina in the late 1930s. Built as a response to the French Canon de 138 mm Modèle 1929, it was meant to have the same range as the widespread 120 mm gun, but with less muzzle velocity and less dispersion.^[1]

Cannone da 135/45 OTO 1937 and 1938, Ansaldo 1938
Type	Naval gun
Place of origin	Italy
Service history
In service	1940 - 1972
Used by	Kingdom of Italy
Wars	Second World War
Production history
Designer	Odero Terni Orlando
Manufacturer	Odero Terni Orlando Ansaldo
Specifications
Mass	6.01 t (13,200 lb)
Length	6.075 m (19 ft 11.2 in)
Shell weight	AP and HE: 32.7 kg (72 lb)
Caliber	135 mm (5.3 in)
Elevation	-5° to +45°
Rate of fire	6-7 rounds per minute
Muzzle velocity	825 metres per second (2,710 ft/s)
Maximum firing range	19,600 m (21,400 yd)

Description

This gun was of loose barrel, jacket and bracket ring, with a horizontal, hand-operated sliding block. The mountings, all with individual cradles for each gun, were either triple (on battleships) or double, with electrical-powered ramming (which, however, was too weak for elevations above 30°, which therefore required hand loading, which rendered the gun unsuitable for anti-aircraft use).^[2]

The gun fired both AP and HE shells, all weighing 32.7 kg (72.1 lb), at a muzzle velocity of 825 M/S (2,707 F/S).

Service

The triple mountings were used on the Andrea Doria-class battleships as a secondary battery (with each having four turrets); four double mountings each were fitted on the three completed Capitani Romani-class cruisers. Single shielded mounts were used to rearm the Premuda (captured Yugoslav destroyer Dubrovnik) and Spalato (captured Yugoslav destroyer Split) while others were built for the never completed aircraft carrier Aquila and Comandanti Medaglie d'Oro-class destroyers. Studies for twin dual-purpose mountings were begun, intended for the two unfinished Etna-class cruisers and the salvaged battleship Conte di Cavour, but this work was still far from finished in 1943.^[3]

The gun proved successful (having only a quarter of the dispersion of the 120 mm gun); however, with the 45° maximum elevation and the limit for mechanical ramming being at 30°, it could not be used against aircraft.^[4][3]

After the war, when the light cruiser Giuseppe Garibaldi was rebuilt in 1961 as a missile cruiser, its original 152 mm turrets were removed, and two new 135 mm double DP turrets were fitted.^[5]

See also

Weapons of comparable role, performance and era

• Canon de 138 mm Modèle 1929