Re: Krylon or Duracoat?
you could just spray over the black with the gray, but that'll leave area for moisture to get under the paint and start corrosion.
if anything, if you want to keep a black look, sparay it black then the gray over it. other than scrapping off some of the finish, you should have a good coat of protection that you will not have to wipe down with oil everytime you touch it. i'd take the action out of the stock too, and spray where you can't see for added protection.
krylon - cheap, easy to spray, easy to touch up after a season of hunting. easy to remove if you want to go another direction....
duracoat - pricey, but you get what you pay for - finish lasts a "lifetime" and alot more durable than krylon. resists normal wear and tear. tough to remove if you decide you want to go another direction....
the problem with clear coating it (in my opinion) is that any knicks or scratches you may get in the clear finish (krylonish type paint) will allow the moisture to start getting in under the paint = rust! being clear, it's tough to spot.