I did one of Cerakotes air dry products on mine. I think I used a 400 or 600 grit piece of sandpaper to do a light scuff. Then wax and grease remover. Let that flash off and then sprayed. It's been on for roughly 6 months and 1 hunt. So far so good. I have done a barrel swap on this build to shoot some NRL hunter. Was shall see.
Hard to say the exact technique, from what u recall the painter preps the carbon, applies the material in a pattern that looks a bit like the forged from manners, then clears over it.
Shameless plug- if you want one like this Altus will hook you up.