Japan
10 cm/50 (3.9") Type 88
Updated 27 May 2012
Used only on the I 65 class submarines (Type KD5).  These submarines were reclassified as I 165 class in 1942.

There were two versions of the gun barrel.  Model Type I used a radially expanded, removable lining while the Model Type I2 was of monobloc construction.  Both types used horizontally sliding breech blocks.

The propellant grain used for this gun was too large and unburnt propellant was present at the muzzle, meaning that the muzzle velocity was unpredictable.
WNJAP_39-50_t88_submarine_pic.jpg

Barrel cleaning a 10 cm/50 gun on an I 65 / I 165 class submarine
Note the horizontal-sliding breech, that there is a single layer/trainer position and that the mounting appears to be a base ring type
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Gun Characteristics
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Designation 10 cm/50 (3.9") Type 88 (Model 1928)
Ship Class Used On I 65 / I 165
Date Of Design 1928
Date In Service 1932
Gun Weight 6,239 lbs. (2,830 kg)
Gun Length oa 208.7 in (5.300 m)
Bore Length 196.9 in (5.000 m)
Rifling Length 169.1 in (4.295 m)
Grooves (32) 0.049 in deep x 0.219 in (1.25 mm x 5.565 mm)
Lands 0.167 in (4.252 mm)
Twist Uniform RH 1 in 28
Chamber Volume 488 in3 (8.0 dm3)
Rate Of Fire
(see Note)		 6 rounds per minute
Note:  This weapon had a firing cycle of 5 seconds but the pneumatic hoist took 10 seconds to deliver a round.
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Ammunition
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Type Fixed
Complete Round Weight 52.9 lbs. (24 kg)
Projectile Types and Weights HE - 28.7 lbs. (13 kg)
Bursting Charge HE - 2.1 lbs. (1 kg)
Projectile Length 15.0 in (38.0 cm)
Propellant Charge 9.11 lbs. (4.13 kg) 30 DC
Cartridge - 24.2 lbs. (11 kg)
Muzzle Velocity 2,904 to 2,936 fps (885 to 895 mps)
Working Pressure 17.9 tons/in2 (2,820 kg/cm2)
Approximate Barrel Life 400 - 700 rounds
Ammunition stowage per gun N/A
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Range
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Elevation 28.7 lbs. (13 kg) HE Shell
Range @ 45 degrees 17,700 yards (16,200 m)
AA Ceiling @ 90 degrees 36,750 feet (11,200 m)
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Mount / Turret Data
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Designation Single Base Ring (?)
   I 65 / I 165 (1):  N/A
Weight  N/A
Elevation -10 / +90 degrees 
Elevation Rate Hand operated, only
Train about +150 / -150 degrees
Train Rate Hand operated, only
Gun recoil N/A
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Data from
"Naval Weapons of World War Two" by John Campbell
"Japanese Warships of World War II" by A.J. Watts
"The Japanese Ships of the Pacific War" by The Koku-Fan
Page History

27 August 2007 - Benchmark
27 May 2012 - Updated to latest template