POSSIBLE- not certain- that you have a Jannsen et fils shotgun. They were located in Belgium, and made nice backlock shotguns.
The little marks and ciphers are what tells the tale. We need good photos, lotta pixels, IN FOCUS, well lighted.
BTW, if one of the marks looks like THIS:
it was made in Belgium. That is the proofmark from the Leige proofhouse.