Canon de 138 mm Modèle 1927

The Canon de 138 mm Modèle 1927 was a medium calibre naval gun of the French Navy used during World War II. Its design was derived from a German World War I design. It was used on the minelaying-cruiser Pluton, the destroyers of the Aigle and Vauquelin classes and the Bougainville-class sloops.

Description
The 40 calibre Mle 1927 was derived from the German World War I 15 cm L/45 UToF gun as mounted on the large torpedo boat SMS S113 received by France as war reparations. It copied the German gun's semi-automatic action and its horizontal sliding block breech. It had an autofretted, monobloc barrel. It used 8.967 kg of powder to push a 40.6 kg shell to a muzzle velocity of 700 m/s.

Mounting
The Mle 1927 was used in single centre-pivot mountings that weighed approximately 13 t that were fitted with a 3 mm thick gun shield. The mount could depress -10° and elevate to +28° which gave it a maximum range of 16600 m. The gun had a firing cycle of 4 or 5 seconds with its automatic spring rammer, but the dredger hoists transporting the shells and cartridge cases slowed the rate of fire down to 8-10 rounds per minute.