My Thoughts are it is a VERY well done re colour case hardening job. I note that the Hinge pin cap was not hardened in place nor does the color of the fore end iron match the body. Normally the fore end iron is case colored at the same time OR Blacked, this appears neither. The acid test would be to remove the fore end iron and look at the underside. this will show the original finish. If it is a very good re finish How would this affect the value given earlier by a poster. ( Rocketman ?)

Hugh Lomas,
H.G.Lomas Gunmakers Inc.
920 876 3745