About 20 years ago, I read an article in Muzzleblasts magazine re rifling a barrel , but the method used was different than others I had heard before or was aware of. I had to try it, and used it to make a pistol barrel.
Unfortunately, I have misplaced that article, and haven't been able to track it down. Perhaps someone here is aware of this method?? 2 pieces of angle iron , and a length of keystock are the main components, along with the cutter and section of hickory rod. There are square holes drilled/filed in the angle iron sections ; one off set from the other. These are clamped down on a bench and as the piece of keystroke is drawn through them, you have your twist [rate is dependant on the distance between the angle iron pieces] This works for cutting one groove at a time since the barrel needs to be rotated to cut the next groove.