Canon de 138 mm Modèle 1923

Canon de 138 mm Modèle 1929
Mle 1929 guns seen on Le Triomphant, 1940
Type	Naval gun
Place of origin	France
Service history
In service	1934—54
Used by	France
Wars	World War II
Specifications
Weight	4,275 kilograms (9,425 lb) Mle 1929 4,650 kilograms (10,250 lb) Mle 1934
Length	7.28 metres (23.9 ft)
Barrel length	about 6.927 metres (22.73 ft)
Shell	separate-loading, cased charge
Shell weight	40.6 kilograms (90 lb)
Caliber	138.6 millimetres (5.46 in)
Breech	semi-automatic, horizontal sliding block
Elevation	-10° to +30°
Traverse	approximately 300°
Rate of fire	depended on mount
Muzzle velocity	800 metres per second (2,600 ft/s)
Maximum firing range	20,000 metres (22,000 yd)

The Canon de 138 mm Modèle 1929 was a medium-calibre naval gun of the French Navy used during World War II. It was used on the large destroyers (contre-torpilleurs) of the Le Fantasque and Mogador classes.

The 50-caliber Mle 1929 was a lengthened version of the Modèle 1927. It used the semi-automatic action of the older gun as well as its horizontal sliding block breech. It had an autofretted monobloc barrel as well. It weighed 4,275 kilograms (9,425 lb), but the later Modèle 1934 weighed 4,275 kilograms (9,425 lb) for some reason, but appears to have been otherwise identical.

The Mle 1929 gun was used in single, hand-worked and trained, center-pivot mountings that weighed approximately 11.7 tonnes (11.5 long tons; 12.9 short tons) that were fitted with a 5 millimetres (0.20 in) thick gun shield. The mount could depress -10° and elevate to +30°, which gave it a maximum range of 20,000 metres (22,000 yd). Ammunition was brought up to the handling room by hoist from the magazines. From there the shells were transferred to the "guttering" (gouttières) which encircled the mount and allowed the shells to line up with the gun's breech regardless of the gun's angle of bearing. Powder cartridges were fed into similar center-line chutes. The gun had a nominal 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 7 rounds per minute. This gun was only used on the large destroyers (contre-torpilleurs) of the Fantasque class.

The Mle 1934 gun was installed in twin-gun, electrically powered Modèle 1934 base-ring "pseudo-turrets" that weighed 34.6 tonnes (34.1 long tons; 38.1 short tons) that were fitted with a 10 millimetres (0.39 in) thick, open-backed gunhouse. These were mounted on the large destroyers (contre-torpilleurs) of the Mogador class. The guns were housed in separate cradles that could be coupled together and could elevate to a maximum of 30° and depress 10°. The underpowered electric motors gave a maximum training speed of 10° per second and a maximum elevating speed of 14° per second. They were initially installed within the mountings, but were moved to the outer sides of the turrets to free up room.