Where as my guns are weapons...they are also tools and are bound to get dinged up. I wouldn't sweat it. I'd say the best you would do is find a shade that matches and pray for the best.
Casey/Birchwood "Gun black" pen.
You can get them on Midway, Brownells...
My bad. They're called Birchwod-Casey Super Black touch-up pen.
Here you go,
Birchwood Casey Super Black Touch Up Pen Flat
I actually think that a battered and bruised weapon looks more interesting. You know that thing has an interesting backstory!
Minus poo stains on pistols...just sayin
Minus poo stains on pistols...just sayin