Degrease the metal, mask areas where paint will cause problems(action openins, bolt,etc.) and paint away. I use mineral spirits and paper towels. It goes without saying that this is an outdoor activity! Remember blue is actually metal altered chemically either by a phosphating process or an oxidizing process. I paint them without using a [primer. Prining may help the paint adhere but it has stayed on just fine without and is much easier to remove without the primer. I routinely paint my turkey guns.. The latest a Brwoning BPS 10 mag..