In the late 1940s the French developed a 100mm gun which according to chars-francaises.net was designated SA47. It armed several French prototype tanks and assault guns (AMX-50, Lorraine 40t, Somua SM, Cannon d'Assaut Lorraine), of which none entered service. Some websites connected to games like Warthunder of the World of Tanks say the gun's barrel was 58 caliber long.

Ballistic performance of the gun may be found in 'L'Armement de Gros Calibe' by Michel Marest and Michel Tauzin (Volume 9 of COMHART publications):

- AP round: projectile weight 15 kg, muzzle velocity 1000 mps, round weight 27 kg

- HVAP round: projectile weight 7.5 kg, muzzle velocity 1275 mps, round weight 20 kg.

Unfortunately I haven't found any info on the ammunition dimensions (cartridge case length/diameter). Maybe someone in this forum knows more on that?

Btw it's also interesting whether the 100mm tank gun was an 'original' design or rather a development of an existing gun (anti-aircraft, naval etc.). Any thoughts?

Best regards

Piotr

The closest to that in Hawkinson is the "100 Sa M 1946", a straight-necked case 755 mm long (no rim diameter given).