Then, before the Internet, there were those that screwed the 3 pieces together and ground the joints to an absolute smooth finish, others taped the joints. Most of the free thinkers, before the Internet, noticed the muzzle ware was tapered, and knew the blast behind the fleeing bullet was under a lot of pressure, to them it was a no brainer, the bullet was escaping the muzzle at the speed of a tree when compared with the gas behind it. They decided the blast escaping behind a flat base bullet was at 90 degree in the beginning, then, as the rifle was used/shot the taper increased progressively. Problem, the escaping gas at the muzzle tipped the rear of the bullet, some bores were counter bored, some were cut off and shortened and re-crowned, now hot high pressure metal cutting gas has nothing to do with the muzzle tapper. Then there is throat erosion.
I do not push cleaning rods, I pull, there are times I have help, when I have help, I am not in charge. And I make bore snakes for my own use.