One thing for sure, most anything you do will be an improvement, as long as you don't etch or move metal, so take it very slow... First thing I'd do is remove the grips, disassemble the unit, and soak the gun parts in in acetone, lacquer thinner, maybe even paint stripper... Then a quick dip in muriatic acid, (removes all bluing) wash and oil...and see what remains??... you're going to have to carefully inspect each part, and replace the missing ones... lot'sa fun really...
... Then when all is good to go, re-finish and re-straw....you'll be a lot more Luger smart when you're through! .....
...best to you, til....lat'r....GT....
