How rust preventive is painting a gun? Is this a good idea for a gun that will be outside a lot? What kind of barrel do you paint blues? Stainless? Nickel? Is it bad to paint any of these? Will the nickel and stainless be less likely to rust after paint than the blued, or will the paint make it not matter. How often do you "touch up" a painted gun? Sorry for all the questions just curious about the subject.