Case hardening

Hi. I hope you can help. I have been given an old shot gun will small remnants of what appears to be case hardening on the reciever. Is this finish gone forever or is there a way to bring it back. Thank you

unfortunately gone forever, but there are restoration specialists that can re-case colour arms after careful polishing followed by the return to the furnace for the heat treatment. Light is one of the things that cause case colour to fade over time. I believe that a varnish like coating called thermaline( not sure of the spelling) was applied post heat treat to preserve the finish. Some case colouring was done in arsenic, this process was done by Stevens arms