France
138.6 mm/40 (5.46") Model 1923
Updated 06 April 2013
An unsatisfactory design with a slow rate of fire.  The mountings had high trunnions to allow higher elevations but this made loading difficult at low elevations.  Fired QF ammunition but still used a Welin breech-block.
WNFR_55-40_m1923_Verdun_pic.jpg

Destroyer Verdun
WNFR_55-40_m1927_Pluton_pic.jpg

Cruiser/Minelayer Pluton
WNFR_55-40_m1923_sketch_pic.jpg

Official 138.6 mm Model 1923 Mounting and Ammunition Sketch from the collection of Robert Dumas
Projectile appears to be AP Model 1924
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Gun Characteristics
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Designation 138.6 mm/40 (5.46") Model 1923
Ship Class Used On Bison (2400 tonnes) and Pluton classes
Date Of Design 1923
Date In Service 1929
Gun Weight 4.04 tons (4.1 mt)
Gun Length oa N/A
Bore Length about 218.3 in (5.544 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire 5 - 6 rounds / minute
Note:  Planned rate of fire was 8 - 9 rounds per minute, but in practice it was closer to the above values.
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Ammunition
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Type Separate
Projectile Types and Weights AP M1924 - 88.0 lbs. (39.9 kg)
HE M1924 - 88.6 lbs. (40.2 kg)
Bursting Charge N/A
Projectile Length AP - 26.9 in (68.3 cm)
HE - 26.9 in (68.3 cm)
Propellant Charge 19.8 lbs. (8.97 kg)
Cartridge - 48.5 lbs. (22 kg)
Muzzle Velocity 2,297 fps (700 mps)
Working Pressure 15.9 tons/in2 (2,500 kg/cm2)
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
Notes:

1) The same size cartridge case was used in all 138.6 mm (5.46") guns from the Model 1910 onwards, although the type and quantity of propellant was not always the same.

2) Actual projectile designations:
       AP M1924 - Opf Mle 1924
       HE M1924 - OEA Mle 1924
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Range
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Elevation With 89 lbs. (40.4 kg) SAP Shell
Range @ 28 degrees 18,150 yards (16,600 m)
Range @ 35 degrees 20,779 yards (19,000 m)
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Mount / Turret Data
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Designation Single Splinter Shielded Mounts
   Bison (4) and Pluton (4):  Model 1924
Weight 12.8 tons (13 mt)
Elevation -10 / +35 degrees
Rate of Elevation N/A
Train About:  +/- 150 degrees
Rate of Train N/A
Gun Recoil N/A
Loading Angle Any
Note:  This mounting had a high trunnion height in order to allow a large maximum elevation.  Although they used an automatic spring rammer for shells - the cartridges being hand loaded - the trunnion height hampered working of the gun at elevations greater than +15 degrees.
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Data from
"Naval Weapons of World War Two" by John Campbell
"French Cruisers:  1922 - 1956" by John Jordan and Jean Moulin
"Destroyers of World War Two" by M.J. Whitley
Page History

16 May 2006 - Benchmark
28 March 2012 - Updated to latest template
06 April 2013 - Added notes on Pluton and mounting sketch