These were of two types, Elswick Pattern "T" and Vickers Mark "G". Elswick guns armed the Dante class while Vickers armed the Doria class. The guns for Cavour were manufactured in Italy by Vickers-Terni while those of Leonardo da Vinci were built by Armstrongs in Britain and those of Cesare were manufactured by the Italian branch of Armstrongs at Pozzuoli in Naples. The mountings were all hydraulically operated.
The delivery of these weapons was greatly delayed, the average being over one year later than planned. For Cavour, this delay would have been even longer, but guns intended for Doria were used when her construction was delayed.
In the 1930s many of these guns were bored out to 32 cm (12.6") for the reconstructed Cesare and Duilio class battleships, but some were retained in their original caliber and used in coastal artillery batteries.
Mark "G" was a fully wire-wound type with inner A, A, B tubes, jacket and breech ring. Pattern "T" had an inner A tube, A tube in two parts joined by screwed collar, B tube and half-length wire, jacket and short breech ring. A pneumatically operated Welin breech block was used for both.
|Designation||12"/46 (30.5 cm) Model 1909|
|Ship Class Used On||Dante Alighieri, Conte di Cavour and Caio Duilio Classes|
|Date Of Design||1909|
|Date In Service||1913|
|Gun Weight||62.5 tons (63.5 mt)|
|Gun Length oa||about 571 in (14.500 m)|
|Bore Length||552.0 in (14.021 m)|
|Rate Of Fire||2 rounds per minute|
|Projectile Types and Weights||APC: 997 lbs. (452 kg)|
|Muzzle Velocity||2,758 fps (840 mps)|
|Approximate Barrel Life||N/A|
|Ammunition stowage per gun||Dante Alighieri: N/A
Conte di Cavour and Caio Duilio: 100 rounds 1
- ^Normal outfit for Conte di Cavour and Caio Duilio was 40 rounds AP and 30 rounds HE fragmentation shells but there was space for 100 rounds.
|20 degrees||26,240 yards (24,000 m)|
|Designation||Two-gun Turrets: Conte di Cavour (2) and Caio Duilio (2)
Three-gun Turrets: Dante Alighieri (4), Conte di Cavour (3) and Caio Duilio (3)
about 500 tons (508 mt)
|Elevation||-5 / +20 degrees|
|Train||Conte di Cavour class
A and X turrets: +150 / -150 degrees
B and Y turrets: +155 / -155 degrees
Q turret: 360 degrees 1a
Caio Duilio class
|Loading Angle||Any angle|
- ^Please note that although Q turret on these ships could train a full 360 degrees, it could not fire directly forward or aft without striking the superstructure of the ship.
- Ammunition supply was hydraulically powered while the elevation machinery was an electrical-hydraulic system.
"Regia Marina: Italian Battleships of World War Two" by Erminio Bagnasco and Mark Grossman
"Naval Weapons of World War Two" by John Campbell
"Italian Warships of World War II" by Aldo Fraccaroli
"The Cavour and Duilio Class Battleships" article by Giorgio Giorgerini in "Warship Volume IV"
"The Big Gun: Battleship Main Armament 1860-1945" by Peter Hodges
"Battleships of World War I" by Peter Hore
02 May 2008 - Benchmark
26 May 2012 - Added mounting notes
02 December 2015 - Changed Vickers Photographic Archive links to point at Wayback Archive
29 May 2021 - Updated to HTML 5 format and added photograph of