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.

• ^The gun itself could fire about 12 or 15 rounds per minute. However, the dredger hoists could supply only 20 rounds per minute per mounting pair and the heavy weight of the projectiles slowed supply from the ready racks, resulting in the lower figures listed above. The hoists could operate only when the ship was heeling less than 20 degrees.

• ^

  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 the SAP 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 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.

Destroyers as completed were given 3 m coincidence rangefinders which were effective only out to 12,000 - 13,000 m (13,120 - 14,220 yards). From 1937 onwards a new 5 m stereo rangefinder was fitted and this allowed accurate fire at longer ranges.

Similar to the Model 1923, these mountings were provided with 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 interfered with movement on the after part of the ship 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, the amidships mounting, was supplied manually from the after hoist. The destroyers Milan and Epervier were completed with additional linear chutes for the cartridges. These chutes delivered the cartridges to the rear of the mountings which kept them "under cover" and thus less exposed to shellfire.

• ^Guns used an automatic spring rammer. This gun had a lower trunnion height than the previous Model 1923 which made loading easier and faster, but this reduction did result in a lower maximum elevation and thus a shorter range than the earlier weapon.
• ^2.12.2Director control for training was provided but elevation was manually computed at the gun mounts.

"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
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Ministère de la défense

22 July 2007 - Benchmark
28 March 2012 - Updated to latest template
06 April 2013 - Added note on Pluton and mounting sketch
18 September 2015 - Additional information for ammunition and mountings
23 February 2018 - Converted to HTML 5 format and reorganized notes