Here is perhaps the authoritatively correct spelling for what everyone else translated. hon hon hon.
déposé
qualité supérieure
acier inexplosible
St-Etienne
crochet encastré
choke rectifié Marsot
fermeture intégrale
spirobloc
portée garantie
canon de surlie
garanti
double épreuve
canon Fanget
PT and one crown - smokeless proof - Poudre T... T for niTro.
Barrel for canon de surlie and steel for acier inexplosible have something to relate with twist steel, surlie meaning made of twisted strands and inexplosible meaning it will not explode - not that it won't blowup but instead of chattering to pieces it will just bust some seams... oh la la... But this is not a Damascus, is it? I figure with all the markings you have, the guy with the stamps got carried away and used everyone he could find.
Could the logo beneath the 'déposé' be the image of a bird, of a hawk type bug as the brand Fanget is also known as 'épervier' for hawk, and they also used bird related designations for various products. I also want to say they used 'le gaulois' in some situations too. The picture given of the soldier could correspond to that of a Gaul, the round shield and heavy sword correspond, perhaps, if there is also a winged helmet and braided hair, we have a perfect fit. But I am drawing on comic book superhero attire at this point.
An opinion on the V shaped proof mark - I don't really see a vee, I think it is more resembling of the Paris proof mark of a crown above a square-ish shield with the picture of the sail boat... a vee-shaped sail? Oui oui. At least the crossed palm of the St-Etienne proof are well defined.
The 65... Since shells come in dangerous lengths, 65, 67, 70, it's all metric and mysterious, I would find it natural for the gun maker to put that number everywhere as a warning. And serial numbers, essentially, I am not sure French hunters care at all.
Authoritative? It really is only a bunch of loose ideas to google around with, not an expert opinion at all.
Have fun