Cannone navale da 381/40

The Cannone navale da 381/40 was an Italian naval gun ordered in 1913 to equip the battleships of the. The ships were cancelled in 1916 and the guns intended for them were diverted to other uses. Seven were turned over the Army and turned into railroad guns, a number were used as coast defense guns and the rest were used on monitors to provide naval gunfire support for the Army. Most of the monitors were disarmed after World War I and their guns were transferred to coastal batteries, but the railroad guns and the coast defense guns were used throughout World War II.

Development
Italy planned a class of four dreadnought battleships to succeed the two ships of the to be armed with 381 mm guns to match the British. The Italians ordered thirty guns in 1913, ten each from Ansaldo-Schneider, Armstrong-Pozzvoli, and Vickers-Terni. The guns had identical ballistic performance, but differed in construction. The government favored the English design and ordered another ten in 1914 from Armstrong-Pozzvoli despite the fact that the Ansaldo guns only weighed 63 LT compared to the Armstrong's 84 LT.

The gun fired an 884 kg armor-piercing at a muzzle velocity of 700 m/s to a range of 19800 m at an elevation of 20°. Mounts that were altered to allow 30° elevation had a maximum range of 27300 m. The rate of fire depended on the mount, but did not exceed 1.5–2 rounds per minute.

The Francesco Caracciolo class were laid down in 1914–15, but the entry of Italy into World War I in 1915 forced her to suspend construction in favor of higher-priority construction and because of material shortages. This freed up their guns to be used for other purposes.

Railroad guns
Seven of the Ansaldo guns were transferred to the Army and turned into railroad guns. The gun plus its mount weighed 212 t and was 24.5 m long. The gun could elevate to a maximum of 25° and it could traverse 2° on its mount. It fired high explosive shells weighing 730 kg and 876 kg to ranges of 33.6 km and 30 km respectively. It also fired a 884.5 kg armor-piercing shell to a range of 30 km.

The guns were delivered during 1916–17, but little is known about their service in World War I. They served into World War II, but, again, little is known of their service.

Naval guns
Two Ansaldo guns were mounted on the monitor ITALIAN MONITOR Faà di Bruno in 1917.

Coast defense guns
A Twin turret was installed at Almalfi Battery on the Cavallino coast (North East of Venice) during World War 1, becoming operational in May 1917.

Weapons of comparable role, performance and era

 * BL 15 inch Mk I naval gun : British naval equivalent
 * 38 cm SK L/45 "Max" : German naval and land equivalent