After the weapon was chosen for use on the Maginot Line, it was decided that the spent cases were disposed of via a flexible tube in case of a JM mount (sometimes a SB mounting as well) or when used in a cupola. When the weapon was mounted in a SP (door) or SB (interior defence) mounting, spent cases were collected in a canvas bag.
The original FM Mle 1924 fired 7.5 x 57mm ammunition introduced in the same year. Five years later, the cartridge was shortened because it was too powerful and caused damage to the barrel. The consequence was that all the FMs Mle 1924 had to be modified in order to fire the new cartridges (7.5 x 54mm), and hence the designation 24/29.
The FMs Mle 24/29 used in the Maginot Line were not the same as the ones used in the field army. The barrel of the FM Mle 24/29 was modified to fire the heavier ammunition. What also distinguished these weapons was the absence of hand guard in front of the triggers and no bipod. These missing features made the FM Mle 24/29 difficult to use out in the field.
|Model 1929 D||heavy ammo||694m/s|
|Model 1929 C||lightweight ammo||840m/s|
|Model 1929 T||tracer ammunition|
|Model 1929 TP||tracer/
Remark: some first generation casemates (1930-1931) had FM Mle 1924/1929 gun positions mounted one above the another. The machine gun in the upper RB gun mount covered the facade or entrance. The lower SB mounted machine gun fired downward in order to defend the ditch. However, the latter was replaced by a hand grenade discharger in later designs.