The first heavy guns used on the earlier battleships were British-made Armstrong. Also, Italy deployed some Skoda and other foreign-made equipment. With the modernization of the Italian fleet, along many innovations in the general area of engineering, came the development of highly sophisticated naval guns. Unfortunately, Italy never realized the true threat of aerial attacks, and consequently anti-aircraft guns were never developed to their full potential. This lack of understanding of the changing warfare was also reflected by the absence of anti-aircraft cruisers in the Italian arsenal.
Ansaldo 381mm.
During the modernization project of the Cesare and the Cavour, the original 12 guns were reduced to 10 and bored out to increase the internal diameter to 320 mm or 12.6 inches thus creating the 320/44 model 1934. The 381/50 model 1934 used on the Littorio class were powerful weapons for the caliber, with a maximum range exceeding that of all other battleship guns despite its modest elevation of only 35 degrees. Only the Japanese 18.1″ (46 cm) and the US 16/50 (40.6 cm) had superior penetration at the muzzle. This superb performance had a price in that their barrel life was only about half that of other nation’s guns.
Ansaldo 320mm.
The 152/50 model 1924 was used on the Trento class, the 8/53 model 1927 on most of the other heavy cruisers and it was thought to be a very good gun. The 6/53 model 1926 and 1929 were on all “Condottieri” class light cruisers except the Garibaldi class which used the 6/55 1933, also used as a secondary gun on the Littorio class. The 1926 and 1929 models differed only in the manufacturer. The 5.3/43 Model 1933 was deployed on the battleship Andrea Doria as a secondary weapon and on the “Capitani Romani” class light cruisers as the main weapon. The 4.7/45 model 1918 was based on a design by Armstrong dating back to WWI, and subsequently built by Vickers in 1924 and by OTO in 1926.
Breda 20/65 mm.
The 4.7/50 model 1926 was first built by Odero-Terni-Orlando (OTO) in 1926, and then continually modified throughout the 1930s by Ansaldo. The 4.7/45 model 1931 was a low power gun exclusively used on submarines. The 4.7/50 model 1933 was built by Odero-Terni-Orlando (OTO) and used only for the modernization of the Cavour class battleships. The 4.7/50 model 1936 and model 1940 was probably the best Italian destroyer guns, and it was used in both single and dual mountings on the Soldati (2nd series) class destroyers.
Breda 37/54 mm.
The 3.9/47 model 1924 and model 1927 was originally designed in 1910 by Skoda, and remanufactured between 1924 and 1927. Used on most cruisers it was considered to be a good AAA weapon. The 3.7 cm/54 Caliber AA MG was a common anti-aircraft gun just like the 9 cm/50 (3.5″) Caliber Model, but it was not plagued with as many technical faults.