You might try Aluminum Black by Birchwood Casey to touch up nicks and scratches on black parts: https://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/blackening-browning/aluminum-black-prod4941.aspxBTW is there a marker to cover fine scratches created by removing the hand guard?
Clearly, the author is on FN's payroll and is attempting to lure people away from the M1A to the (insanely overpriced) SCAR platform.But I'm still scratching my head as to its point. I mean... why even write it in the first place?