they are kind of a flat black. one of the spray and bake products should work.
If both pieces are steel, I suspect they are, I would knock the black off the mounting base with some steel wool and a bit of elbow grease, then, once the two are mated, warm them up a little bit in boiling water (drop them in a coffee mug), rinse off, and apply cold blue using a cotton q tip until you get the desired result. Me - I like the dull sheen of the peep. Once blued, you could knock it all back as a single unit with fine steel wool to get a good patina. Remember to do the same to the mounting screws for consistency. Age, and use, will just make it get better.
