If you are just trying to repair the black finish, then don't just paint it. That's just a cheap, temporary fix. Paint WILL flake, guaranteed. Take your gun to a gunsmith, to be parkerized. Pakerized finishes look good, and are durable (but not rust proof!) You can also try armacoat, or duracoat finishes, if you want to do it yourself. They are a lot more difficult, and require compressed air & a spray gun, but way more durable than ordinary spray paint.