There were a bazillion mom n pop gun makers in Belgium, and it's often real hard to find any history on the small shop made guns.
In looking at the rust and corrosion inside and out I would be averse to shooting the gun. Maybe make some light BP blanks to blow smoke. I'd give it a value of $150-$200 from what I see in the photos. That's conservative, I know, but not having it in hand, conservative is the best I can do.
It was a very nice gun once. It's too bad WWII ruined it (my assumption).
I sure enjoyed seeing the gun.
L2S