Italy120 mm/50 (4.7") Models 1926 to 1940

Italy
120 mm/50 (4.7")
Ansaldo Models 1926, 1936, 1937 and 1940
OTO Models 1931, 1933 and 1936
Updated 29 December 2007

First manufactured by Ansaldo in 1926, this gun was continually modified throughout the 1930s by both Ansaldo and Odero-Terni-Orlando (OTO). Fired separate ammunition and used horizontal sliding breech-blocks.

These guns in the twin mountings suffered from excessive dispersion which seems to have been the result of mounting the barrels too closely together. On later destroyers, a single 120 mm/50 (4.7") mounting was used to replace obsolete 120 mm/15 (4.7") star-shell howitzers and thus improved the ship's firepower.

Destroyer Navigatori
Amidships 120 mm/50 (4.7") Ansaldo Model 1926

Battleship Guilio Cesare with 120 mm/50 (4.7") OTO Model 1933
ANB Photograph

Destroyer Alfredo Oriani with 120 mm/50 (4.7") Model 1936
This destroyer was later ceded to France and renamed D'Estaing
Marina Militare Photograph

Destroyer Bombardiere
Fore and aft mounts are 120 mm/50 (4.7") Ansaldo Model 1937
Amidships mount is Ansaldo Model 1940

Gun Characteristics .

Designation	120 mm/50 (4.7") Ansaldo Models: 1926, 1936, 1937 and 1940 OTO Models: 1931, 1933 and 1936
Ship Class Used On	See Mounting Data, below
Date Of Design	1926
Date In Service	1936
Gun Weight	5.1 tons (5,552 kg)
Gun Length oa	252.0 in (6.400 m)
Bore Length	236.2 in (6.000 m)
Rifling Length	195.2 in (4.958 m)
Grooves	about 36
Lands	N/A
Twist	Uniform RH 1 in 30
Chamber Volume	920.1 in³ (15.08 dm³)
Rate Of Fire	6 - 7 rounds per minute

Ammunition .

Type	Separate
Projectile Types and Weights	HE - 51.8 lbs. (23.15 kg)
Bursting Charge	N/A
Projectile Length	N/A
Propellant Charge	21.4 lbs. (9.7 kg)
Muzzle Velocity	3,117 fps (950 mps) Later reduced to 3,018 fps (920 mps)
Working Pressure	20.0 tons/in² (3,150 kg/cm²)
Approximate Barrel Life	N/A
Ammunition stowage per gun (see Note)	Navigatori: 182 rounds Others: N/A
Note: Outfit for Navigatori class was 408 AP, 672 HE, 120 incendiary and 100 star shells plus an unspecified number of ready rounds.

Range .

Elevation	With 51.8 lbs. (23.15 kg) HE shell
Range @ 45 degrees @ 3,117 fps (950 mps)	24,060 yards (22,000 m)
Range @ 35 degrees @ 3,018 fps (920 mps)	19,900 yards (18,200 m)
Range @ 45 degrees @ 3,018 fps (920 mps)	21,430 yards (19,600 m)

Mount / Turret Data .

Designation	Twin Mountings Navigatori (3), Dardo (2) and Folgore (2): Ansaldo 1926 Soldati (2): Ansaldo 1936 and 1937 Maestrale and Oriani Classes: OTO 1931 and 1936 Conte Di Cavour Class: OTO 1933 Single Mounting Soldati (1): Ansaldo 1940
Weight	Ansaldo 1926: 19.92 tons (20.24 mt) Ansaldo 1936 and 1937: 21.26 tons (21.60 mt) Ansaldo 1940: 11.81 tons (12.00 mt) OTO 1931: 17.37 tons (17.65 mt) OTO 1933: 33.46 tons (34.00 mt) OTO 1936: 22.44 tons (22.8 mt)
Elevation	Ansaldo 1926: -10 / +45 degrees Ansaldo 1936: -10 / +40 degrees Ansaldo 1937: -10 / +42 degrees Ansaldo 1940: -10 / +45 degrees OTO 1931: -7 / +33 degrees OTO 1933: -10 / +42 degrees OTO 1936: -10 / +35 degrees
Elevation Rate	N/A
Train	about +150 / -150 degrees
Train Rate	N/A
Gun recoil	N/A
Notes: 1) Twin mountings had electric power for training and elevation. 2) The OTO 1933 mountings used on the Conte Di Cavour class were different from the concurrent ones used on destroyers in that they were equipped with mechanical rammers, better shell and propellant hoists and had a much thicker shield.

Data from
"Naval Weapons of World War Two" by John Campbell
"Italian Warships of World War II" by Aldo Fraccaroli
"Italian Super Destroyers" article by Elio Andò in "Warship Special 2: Super Destroyers" edited by Antony Preston
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