The important parts are to have the muzzle square to the bore (and flat), and to have a smooth, even crown.
I know a fellow who could chop a barrel with a hacksaw, square it up by eye with a file, and crown it with a big brass round-head screw and lapping compound, and have it shoot better than new. He is also an old-timer machinist, who learned how to use a file with precision when he was an apprentice. We mortals could probably use a good piloted crowning reamer to help cover up the inaccuracies of the cut.