I have a friend who is a certified applicator of Duracoat. Yesterday he did a bolt and carrier in Parkerize color for a retro A1 project I have going. I'll let you all know how it holds up when I shoot it, i.e. whether it flakes off or not.
However, if it's anything like the M1A he did for me, carbon/dirt will wipe right off. The flash hider splines and the face of the bolt only need wiped off with a rag. No scrubbing or scraping required. Up to this point I've always had to use a green scratch pad to remove the brass and marks off of the bolt face. Now it just wipes away. Of course the splines and the bolt face on an M1A are not "friction" areas where there is much metal to metal rubbing going on. Those places that are contact areas have some Duracoat worn off (like the bolt lugs and runway), but then again true parkerizing will rub on high wear areas too.
I don't think that an AR bolt/carrier is a "high rub" zone, do you all? At least internally the gas rings are what makes the most contact inside the carrier, right? The back of the bolt where the shit always builds up should be unaffected by contact.