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.

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).

The gun fired both AP and HE shells, all weighing 32.7 kg (72.1 lb), at a muzzle velocity of 825 mps (2.707 fps).

Service
The triple mountings were used on the s as a secondary battery (with each having four turrets); four double mountings each were fitted on the three completed s. 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 s. Studies for twin dual-purpose mountings were begun, intended for the two unfinished  cruisers and the salvaged battleship ITALIAN BATTLESHIP Conte di Cavour, but this work was still far from finished in 1943.

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.

After the war, when the light cruiser ITALIAN 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.

Weapons of comparable role, performance and era

 * Canon de 138 mm Modèle 1929