The only issue I ran into with coated bullets is when I pushed them over 2700fps in a 308w.
Picture of the clean 308 bbl/throat & leade area
The black streaks came out with boretech eliminator
Never had the issue until I started pushing the pc'd bullets over 2700fps. Everything under 2700 in rifles/pistols/revolvers always cleaned up with 1 wet patch & 1 dry patch, no brushing needed.