They aren't really Xs, they are crossed sheaths of wheat, a St. Etienne proofhouse mark. They signify triple proof. It is the highest level of proof in Europe.
Afraid you will have to pattern the gun to know about what you have. The French use points of choke, which, will depend also on how the barrel is bored.

Thanks, Treb, but, I am just the messenger boy.

Best,
Ted