Metal work or woodwork? The bluing if your satisfied with the polish only needs to have any oily residue removed if your going to paint, warm water wash and soak, good rinse. Chemical finish buff and polish to remove any of the old finish, then a hot water wash, a good place to do this is an automotive engine rebuilder with a hot tank, and a super rinse use cotton gloves over disposable latex for final handling, finish as per manufacturing instructions, best left to professionals with the necessary tanks.
Woodwork go to CZ for original finish, if it's an oil finish go to library most older gun books or furniture books have the story. If it's a coating get it's name and go to a paint store and get a stripper that's suited and refinish to your liking.