The Canon de 305 mm Modèle 188745 calibergun was a typical French built-up gun of the period. It used a Welin interrupted-screw breech and separate loadingbagged charges and projectiles. It was mounted in single gun turrets which had a couple of unusual features. First, most of the turret's operating machinery was housed inside the turret, with only an armored tube to protect the ammunition hoists. This made little difference in the overall weight of the turret but did raise the machinery higher in the ship than the turrets of other nations, which did have implications for stability. Secondly, they used a hydraulic pivot to lift the turret when it rotated; this was lowered onto a seating ring when the turret was in the proper position to fire.
Naval use
The mle 1887 equipped three French pre-dreadnought battleships:
Carnot - The mle 1887 formed the primary armament of this pre-dreadnought battleship. There were two single gun turrets mounted fore and aft of the ship's superstructure. These were complemented by a secondary armament of two Canon de 274 mm Modèle 1887 single gun turrets port and starboard of the ship's superstructure. The four turrets together formed a lozenge pattern.
Jauréguiberry - The mle 1887 formed the primary armament of this pre-dreadnought battleship. There were two single gun turrets mounted fore and aft of the ship's superstructure. These were complemented by a secondary armament of two Canon de 274 mm Modèle 1887 single gun turrets port and starboard of the ship's superstructure. The four turrets together formed a lozenge pattern.
Bouvines class - The mle 1887 formed the primary armament of the Bouvines and Amiral-Tréhouart. There were two single gun turrets mounted fore and aft of the ship's superstructure. The ship's secondary armament consisted of eight 100 mm 45 caliber Modèle 1892 guns, four of which were mounted in individual casemates. The other four were carried on pivot mounts with gun shields on the shelter deck directly above the four casemated guns on the corners of the superstructure.
Railway artillery
The Obusier de 370 modèle 1915 was a conversion of the mle 1887 by shortening the barrels to 25 calibers and boring them out to. It was proposed to convert eight gun barrels to railway artillery with another four spare barrels. The barrels for these guns would come from decommissioned ship's of the Charles Martel class of pre-dreadnought battleships and Bouvines class coastal defense ships. The work of building the guns was split between Schneider and Batignolles each producing four guns. There were slight differences between the two groups of four guns. For example, a 370 mle 1915 with gun barrels from the battleship Charles Martel weighed 127 tonnes, while the others from the Bouvines class of coastal defense ships weighed 134 tonnes. Whether there were any ballistic differences between the finished pieces is unknown. The Obusier de 370 mm mle 1915 was considered a howitzer instead of a gun, so range and velocity were not primary considerations. Instead, high angle fire, projectile weight, and explosive yield were the primary considerations. Traverse was accomplished by using a section of curved track. Seven of the eight guns survived the first world war and four were captured by the Germans during the second world war their designation was 37 cm H 711 and they used them throughout the second world war.
Ammunition
The mle 1887 was equipped with three different types of shell:
