LehighBrad - Kettenburg is an artist. His aged metal and wood finishes are as sophisticated and as artistic as the architecture and furniture on his guns. To produce a “fake” as Kettenburg calls them, you first need to understand what old metal and wood look like, then figure out how to reproduce the ageing. This is not simple, so plan on spending a lot of time experimenting before you finally get it right.
If you follow some of the recipes recommended here, you will end up with an “aged” finish that is every bit as convincing as the “antiqued” finish on lamps at the furniture store. And, if you don’t age the wood as well, you’ll end up with the incongruity of old metal and new wood which, to me at least, is at best a mixed metaphor.
I think the best advice you’ve gotten is to finish it as new, shoot it a lot in all kinds of weather, take it hunting and get some honest wear on the stock, and in a couple of years you’ll have just what you’re looking for.