Hi, I'm into making a few black powder barrels, mainly for .45, .50, for patched round ball with cut rifling. Now I see that Cold grain and Rice barrels are top of the range and have rifling that's rounded at the bottom of the groves, is this better than the square type of rifling for a P/B barrel with a twist of 1-56" or 1-66" accuracy wise . The main thing is it would be harder to make a rifling cutter for a rounded grove but the barrels are sort after for there accuracy. So is there any difference if you are looking for a P /B barrel. Homebrew.357.