Italy
152 mm/55 (6") Model 1934
152 mm/55 (6") Model 1936
Updated 12 January 2013
A good anti-destroyer weapon, this was the secondary gun on the Littorio class battleships and the main gun on the Garibaldi class (5th "Condottieri") light cruisers.  The Model 1934 was made by Ansaldo and were of monobloc construction with a horizontal sliding breech block.  The Model 1936 was made by OTO and was constructed of two tubes, loose liner and a horizontal sliding breech block.

These guns were a significant improvement from earlier 152 mm (6") guns in that they were more widely spaced in the turrets, were separately sleeved and had a lower and more reasonable muzzle velocity from the beginning.  The increase in barrel length from the previous weapons was in attempt to obtain improved thermodynamic performance.  Whatever the reasons, these new guns did prove to be the most accurate of all the Italian 152 mm (6") guns in service during World War II with dispersion patterns with APC being 260 to 300 feet (80 to 90 m) at a range of 19,140 yards (17,500 m).

Historical note:  These cruisers were named after famous leaders ("Condottieri") of mercenary bands in Renaissance Italy.
WNIT_6-55_m1936_Duca_degli_Abruzzi_pic.jpg

Light Cruiser Luigi di Savoia Duca degli Abruzzi
(Name was usually shortened to just "Abruzzi")
Picture copyrighted by M.J. Whitley
WNIT_6-55_m1936_Duca_degli_Abruzzi_speed_pic.jpg

Nice picture of Abruzzi at speed
The circular objects under the gun barrels are the ejector ports for the spent cartridge cases
Marina Militare Photograph
WNIT_6-55_m1936_Duca_degli_Abruzzi_firing_pic.jpg

Abruzzi firing her guns in the post-war period
Note the radar antenna on the foremast
Marina Militare Photograph
WNIT_6-55_m1936_Giuseppe_Garibaldi_gun_pic.jpg

Giuseppe Garibaldi having a 152 mm gun removed in the late 1950s during her conversion to a missile cruiser
The case ejector tube under the gunbarrel can be clearly seen in this photograph
Marina Militare Photograph
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Gun Characteristics
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Designation 152 mm/55 (6") Models 1934 and 1936
Ship Class Used On Littorio and Garibaldi classes
Date Of Design 1934 / 1936
Date In Service 1940
Gun Weight 8.9 tons (9,689 kg)
Gun Length oa about 348 in (8.840 m)
Bore Length 330.0 in (8.382 m)
Rifling Length 287.4 in (7.301 m)
Grooves 40
Lands N/A
Twist Uniform RH 1 in 30
Chamber Volume 1,537 in3 (25.19 dm3)
Rate Of Fire 4 - 5 rounds per minute
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Ammunition
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Type Separate
Projectile Types and Weights AP - 110 lbs. (50 kg)
HE - 97.9 lbs. (44.4 kg)
Bursting Charge AP - 2.05 lbs. (1.0 kg)
HE - 5.18 lbs. (2.3 kg)
Projectile Length AP - 24.8 in (63.0 cm)
HE - N/A
Propellant Charge 36.05 lbs. (16.35 kg)
Muzzle Velocity AP - 2,986 fps (910 mps)
HE - 3,100 fps (945 mps)
Working Pressure 20.8 tons/in2 (3,270 kg/cm2)
Approximate Barrel Life N/A
Ammunition stowage per gun Littorio:  210 rounds
Others:  N/A
Notes:

1) New gun MV for HE was 3,133 fps (995 mps).

2) Outfit for Littorio class was 840 AP, 1,428 HE and 252 AA.  I lack information on the AA projectile, but they probably would have been similar in size and weight the the HE projectile.
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Range
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Elevation With 110 lbs. (50 kg) AP shell With 97.9 lbs. (44.4 kg) HE Shell
Range @ 45 degrees 28,150 yards (25,740 m) 27,231 yards (24,900 m)
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Mount / Turret Data
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Designation Two-gun Turrets
Garibaldi (2):  Model 1934

Three-gun Turrets
   Littorio (4) and Garibaldi (2):  Model 1934
   Vittorio Veneto (4) and Roma (4):  Model 1936
Weight  Twin:  N/A
Triple:  133.3 tons (135.4 mt) [not including shield]
Elevation -5 / +45 degrees
Elevation Rate N/A
Train about +120 / -120 degrees
Train Rate N/A
Gun recoil N/A
Loading Angle -5 to +20 degrees
Notes:

1) These mountings were electrically powered training and elevation.  Rammers were pneumatically powered.  Cartridge cases were ejected from tubes under the gun barrels.

2) In the twin mountings, each gun had separate shell and cartridge endless chain hoists.  These ended below the gun house and ammunition was transferred to the loading trays by swinging arms which pivoted about the trunnions.  In the three-gun mountings there were lower endless chain hoists for each gun which ended in a handling room locted below the gunhouse.  Upper endless hoists for each gun ran up to the gunhouse.

3) The gun axes were about 50 in (127 cm) apart for both the two-gun and three-gun mountings.
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Data from
"The Littorio Class:  Italy's Last and Largest Battleships 1937 - 1948" by Erminio Bagnasco and Augusto de Toro
"Naval Weapons of World War Two" by John Campbell
"Italian Warships of World War II" by Aldo Fraccaroli
"Anatomy of the Ship:  The Cruiser Bartolomeo Colleoni" by Franco Gay and Valerio Gay
"Cruisers of World War Two" by M.J. Whitley
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Page History

21 September 2008 - Benchmark
26 May 2012 - Updated to latest template
19 December 2012 - Added information on gun construction
12 January 2013 - Added ammunition information