Nice little gun, would have been made for short black powder shells, made in 1900 - 1914ish'. Seem to be fewer in that gauge
Made by SPI group, in Belgium -Jansen,Neumann,Francotte.
I have a Neumann Bros version, also Damascus, owned by my father, probably bought in the '20s, but very short stock, not cut.
The chrome on yours is not likely to be original.....
Somewhat worn (lever to left), too bad about the.... decor....
Value? Mine priceless due to history, without that maybe $300 - $500?? Polished and plated.....dunno.