As for the fourth
https://www.gunbroker.com/item/878878988This is not a French gun. It was retailed by Heut Armorier in Lille.
I'll leave it to the Germanophiles to interpret these marks:
https://live.amoskeagauction.com/m/view-auctions/catalog/id/50?lotnum=775turns out three of the four guns were sold last month...with slightly more informative descriptions.
I suppose this engraving could be a French gun (Scott Spindle on the top lever):
I don't have a clue about the proof marks on the action flats:
Broken stock and all, it's a handsome gun.