Italy
100 mm/47 (3.9") Model 1931 and Model 1937
Updated 23 September 2012
A slightly improved version of the 100 mm/47 Model 1928 and used in single mountings on smaller warships.  Manufactured by OTO.  Well-liked, but used in mountings with low maximum elevations which meant that they were not really suitable for the anti-aircraft role.
WNIT_39-47_m1931_Ariel_pic.jpg

100 mm/47 OTO 1937 guns on Torpedo Boat Ariel
Photograph copyrighted by Elio Andò
WNIT_39-47_m1931_Ibis_pic.jpg

100 mm/47 Model 1937 formerly on the Corvette Ibis
In the background is a twin 100 mm/47
Image courtesy of Museo Tecnico Navale della Spezia
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Gun Characteristics
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Designation 100 mm/47 (3.9") Models 1931, 1935 and 1937
Ship Class Used On Spica, Ariete, Orsa, Animoso and Gabbiano Classes
Date of Design 1931, 1935 and 1937
Date In Service 1932
Gun Weight N/A
Gun Length oa 196.3 in (4.985 m)
Bore Length 185.0 in (4.700 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume 473.5 in3 (7.76 dm3)
Rate Of Fire 8 - 10 rounds per minute
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Ammunition
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Type Fixed
Complete Round Weight N/A
Projectile Types and Weights HE - 31.3 lbs. (14.2 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge N/A
Muzzle Velocity
(see Note)		 2,805 fps (855 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
Note:  The muzzle velocity was originally 2,953 fps (900 mps) but this was reduced in an effort to reduce dispersion.
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Range
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Elevation With 31.3 lbs. (14.2 kg) HE shell
Range @ 45 degrees 16,840 yards (15,400 m)
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Mount / Turret Data
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Designation
(see Note 1)		 Single Mountings
   OTO 1931
   OTO 1935
   RM 1937
   OTO 1937
Weight  OTO 1935:  6.2 tons (6.3 mt)
OTO 1937:  6.7 tons (6.8 mt)
Elevation OTO 1931:  -6 / +45 degrees
Others:  -10 / +60 degrees
Elevation Rate Manually operated, only
Train 360 degrees
Train Rate Manually operated, only
Gun recoil N/A
Notes:

1) The OTO 1931 gun was used in the OTO 1931, OTO 1935 and RM 1937 mountings.  The OTO 1937 gun was used in the OTO 1937 mounting.

2) The RM 1937 mounting was little used and the OTO 1931 mounting was replaced where possible during World War II with the OTO 1935 and OTO 1937 mountings in order to increase AA capability.
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Data from
"Naval Weapons of World War Two" by John Campbell
"Italian Warships of World War II" by Aldo Fraccaroli
Page History

16 May 2006 - Benchmark
26 May 2012 - Updated to latest template
23 September 2012 - Added picture of musuem gun