To hazzard a guess on the "marks".... given that you are in France....my guess is that they are 'proof marks".... to show that the gun has been inspected or proof tested (pressure check) as part of the import process.

I've read posts that this is required in Germany (IIRC) so I'm guessing France might have the same.........would have to check but don't remember any proof markings on my US gun!