It looks like the whole gun was hot blued at one time. Estate gun, this is the way it came in the shop. Extractor & sights missing. Very nice locks (no interior markings) and excellent lock inletting.
Anyone know anything about the maker? I haven't got all the references, all I can find is one sentence in Carder about a shotgun.
David, that little tiny mark on the short rib behind the loop looks like A through a B?