Belgian sourced gun peddled in Paris. The sidewise horseshoe around the chamber diameter & length(65mm) makes it post 1924 and if the "d" is the date code it would have been proofed in 1925. So if the chamber length is 70mm there has been some modification since it left the proofhouse. From the pics right off, I don't see chopperlump tubes.

Kind Regards,

Raimey
rse