Touching up asr10 paint

anyone have a suggestion for what paint I should use to touch up my asr10?

Don't use any paint. Use a black permanent marker, I find cd markers best, as they don't have the weird purple tint alot of others have.
Same trick can be used to get faded black screws looking new.

I used auto touch-up paint, the paint-pen kind. You can tell where the scratches are, if you're looking for them, but other than that, it blends in fairly well.