All true, but an additional consideration with black powder express rifles is that a rough bore with what might be called a 'salt'n'pepper' appearance will often improve considerably with the passage of a couple hundred jacketed bullets in 'N for B' loads.

I have 2 express doubles that had rough bores at acquisition, but were nevertheless accurate and well-regulated. The bores improved from what looked like 40% - 50% bore condition to about 80% shiny with some determined shooting! I should add that accuracy and regulation were unaffected during this 'improvement'.