An unsatisfactory design with a slow rate of fire. The design was started soon after trials of the previous 130 mm Model 1919 showed them to be unsatisfactory, but the new gun also proved to be unsatisfactory. The mountings had raised trunnions to allow higher elevations but this made loading difficult at low elevations. Fired QF ammunition but still used a Welin breech-block.
Nomenclature note: These guns were often referred to as being 14 cm during the years immediately following World War I.
| Designation | 138.6 mm/40 (5.46") Model 1923 |
|---|---|
| Ship Class Used On | 2400 tonnes Destroyers: Bison class
Training Cruiser: Pluton |
| 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 1 |
- ^Planned rate of fire was 8 - 9 rounds per minute, but in practice it was closer to the above values. Used a automatic loading tray similar to the one introduced on the 130 mm Model 1919.
| Type | Separate |
|---|---|
| Projectile Types and Weights 1a 2a 3a | SAP M1924: 88.0 lbs. (39.9 kg)
HE M1928: 88.6 lbs. (40.2 kg) Starshell M1925: 66.1 lbs. (30.0 kg) |
| Bursting Charge | SAP: 5.1 lbs. (2.3 kg) Melinite
HE: N/A |
| Projectile Length | SAP: 26.9 in (68.3 cm)
HE: 26.9 in (68.3 cm) Starshell: N/A |
| Propellant Charge | 19.8 lbs. (8.97 kg) BM7
Cartridge: 48.5 lbs. (22 kg) |
| Cartridge Case Type, Size and Empty Weight 4a | Model 1910: Brass, 900 x 187.5 mm, N/A |
| 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 | Bison: 100 rounds 5a Pluton: N/A |
- ^
Actual projectile designations SAP M1924 OPFA Mle 1924 HE M1924 OEA Mle 1928 Starshell OEcl M1925 - ^The French designation for the SAP shell is the same as used for AP but this projectile lacked an AP cap.
- ^Shell colors (dispositif K) were introduced in the late 1930s for the SAP shell with red issued for the lead ship in the flotilla, green for the second and white (later yellow) for the third.
- ^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.
- ^Magazines for the Bison class held 100 SAP and HE rounds per gun plus 85 starshell. Stowage racks for 24 ready rounds were provided for guns No. 1, 2, 4 and 5 and 48 rounds for gun No. 3.
| Designation | Single Splinter Shielded Mounts 1c Bison (5) and Pluton (4): Model 1924 |
|---|---|
| Weight | 12.8 tons (13 mt) |
| Elevation | -10 / +35 degrees 2c |
| Rate of Elevation | N/A |
| Train | About: +/- 150 degrees |
| Rate of Train | N/A |
| Gun Recoil | N/A |
| Loading Angle | -10 / +15 degrees 3c |
- ^The original gunshields were lightly constructed and provided little protection for their crews. These were replaced soon after completion by a "wrap around" shield similar to those for the 130 mm Model 1919.
- ^The trunnion height for this mounting was 6.3 inches (16 cm) lower than the preceding 130 mm Model 1919 mountings but it was still relatively high 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.
- ^As completed there were problems with the extraction of the cartridge cases but these were quickly rectified. A larger problem was the underpowered rammer as the heavy projectile and case could not be loaded at elevations greater than 15 degrees. Shells were manually moved from the hoists to the guns which proved very difficult in heavy weather. This was rectified on the destroyers by the novel method of providing chutes or "guttering" which ran from the hoists to the gun positions, with projectiles delivered by the port chute and the cartridges by the starboard chute. The chutes for No. 5 gun fed interfered with movement and so were normally stowed until firing was imminent. As completed these chutes could supply ammunition only when the guns were trained on the beam but they were modified in the late 1930s to encircle the mountings. Gun No 3. was originally supplied by an overhead cable intended to carry both projectiles and cartridges from the after hoist but this proved impractical and instead ammunition was carried manually to this position.
- These were the first French destroyers to have the forward hoists fully enclosed which improved ammunition supply during bad weather. Ammunition was brought up to a deckhouse forward of the bridge. The aft hoists remained open with blast shields to the sides.
- Problems with these mountings during construction led to ships running machinery trials without guns, fire control gear and other equipment. The high speeds achieved during these trials were not, of course, replicated during their service lives.
"Naval Weapons of World War Two" by John Campbell
"French Cruisers: 1922 - 1956" and "French Destroyers: Torpilleurs d'Escadre & Contre-Torpilleurs 1922 - 1956" both by John Jordan and Jean Moulin
"Destroyers of World War Two" by M.J. Whitley
16 May 2006 - Benchmark
28 March 2012 - Updated to latest template
06 April 2013 - Added notes on Pluton and mounting sketch
13 September 2015 - Additional information for ammunition and mountings
31 December 2018 - Converted to HTML 5 format and reorganized notes