Unlike previous 40 mm guns, Bofors abandoned the four-round clip for the 57 mm guns as they considered that the loaders could not easily handle the heavier clips.  Instead, for this weapon the loaders dropped individual rounds into ammunition boxes which in turn feed quadrant-shaped hoppers.  The hoppers were mounted at the gun's trunnions such that the position of the gravity feed was always horizontal and perpendicular to the gun's axis.  Similar feed systems can be seen in other postwar Bofors and Breda weapons.

In a review following the end of World War II, the French Conseil Superieur decided that the 40 mm Bofors heavy AA MG was inadequate against modern aircraft.  That decision led to the purchase of the Bofors 57 mm AA gun.  These guns were installed in a French-designed twin turret which was used on Jean Bart after World War II when she was extensively modernized and on new destroyer construction.

Jean Bart did not receive her guns until the winter of 1951-52, as production had been delayed by credit blockages in France during 1948-49.  Jean Bart as completed probably had the best conventional AA armament ever fitted to a battleship, but the effectiveness of these weapons in the jet age is questionable.

Guépratte 20 October 1961
The 57 mm mounts are in "B", "P" and "Q" positions while 127 mm/54 twin mounts are in "A", "X" and "Y" positions
Photograph copyrighted by L & L van Ginderen

57 mm/60 twin mount on Jean Bart in 1953
At left are 100 mm/55 Model 1945 AA guns
ECPA(D), Ft. d'Ivry Photograph

In the foreground is one of the 57 mm/60 AA mountings on Jean Bart in 1956
In the background are three 100 mm/55 Model 1945 twin mounts 
Henri Landais Collection Photograph

Stern 57mm/60 mountings on Fast Escort (L'escorteur rapide) Le Picard in April 1962
Établissement de Communication et de Production Audiovisuelle de la Défense (ECPA D) Photograph No. D46-01-04