138.6 mm/40 (5.46") Model 1927
Updated 06 April 2013

The unsatisfactory performance of the 138.6 mm (5.46") Model 1923 resulted in a new design based upon a design from a former enemy.

The Model 1927 was developed from the German 15 cm (5.9") gun used on the destroyer S113, which was taken over by France at the end of World War I and renamed Amiral Sénès.  Like the German weapon, the Model 1927 was fitted with a horizontal sliding wedge breech-block of semi-automatic operation.

The barrel was autofretted and used the same shells and cartridge cases as in the 138.6 mm Model 1929, but with a smaller propellant charge.

A note on sources:  "Naval Weapons of World War Two" says that the cruiser/minelayer Pluton carried this weapon, but recent research by John Jordan and Jean Moulin in their "French Cruisers:  1922 - 1956" has determined that she carried the older Model 1923.


"2400 Tonnes" Destroyer Cassard in 1933
Ministère de la Défense Photograph


Official 138.6 mm Model 1927 Mounting and Ammunition Sketch from the collection of Robert Dumas

Gun Characteristics
Designation 138.6 mm/40 (5.46") Model 1927
Ship Class Used On Aigle (2400 tonnes), Cassard (2400 tonnes) and Le Malin (2610 tonnes) classes
Date Of Design 1927
Date In Service 1930
Gun Weight N/A
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 8 - 10 rounds per minute
Note:  The gun itself could fire about 12 or 15 rounds per minute.  However, the dredger hoists could not keep up with this speed, resulting in the lower figure listed above.
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) BM7
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

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

Elevation With 89 lbs. (40.4 kg) SAP Shell
Range @ 28 degrees 18,150 yards (16,600 m)
Mount / Turret Data
Designation Single Mountings
   Aigle (4), Cassard (4) and Le Malin (4):  Model 1927 CP
Weight  12.8 tons (13 mt)
(see Note)
-5 / +28 degrees
Elevation Rate N/A
Train about +150 / -150 degrees
Train Rate N/A
Gun recoil 14 in (36 cm)
Loading Angle Any
Note:  Used an automatic spring rammer.  This gun had a lower trunnion height which made loading easier and faster, but did result in a lower maximum elevation and thus a shorter range than the earlier Model 1923.
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
Ministère de la défense
Page History

22 July 2007 - Benchmark
28 March 2012 - Updated to latest template
06 April 2013 - Added note on Pluton and mounting sketch