The 6mm Francotte was originally thouht to be a shortened version of the Velo Dog Revolver cartridge but it is a separate cartridge identified from the SFM factory drawing #10150 dated 1912 as being used in a .22 Francotte Carbine Rifle. (Dixon Ref. FR19)

The cover of the 6mm Francotte carbine manual. (Source : WB Dixon)