A Belgian SA/DA knockoff of the S&W Schofield pistol. It was made in 1887 apparently in Liege, Belgium. it appears to be about a .44 Russian, but the frame is BP only. I think it might have been a civilian version, as the grips appear to be Ivory. It still locks up tightly on single and the trigger pull is heavy in double action, but the cylinder rotates when the hammer is at rest.
Just a unusual old gun I received as a wedding gift (among others) from my mother-in-law.