It says: “A Paris Calibre Verifie Brevte S.G.D.G” and has a ‘MF’, a wheel, and a “MF” in reverse.
There is a slotted scale along the top edge that measures the diameter of the pin (scale runs from 1-10 and 1-24 with each slot varying in width.)
On the surface of each side there are circular indentions in varying sizes (1-8, and 9-21 on the opposite side).
Any more info on this? and would you imagine it is for cartridges not shot shells?