AWESOME question I have often wondered the same. Now from a revolver stand point over size ball (within reason of course not a .454 in a .36cal) the shaved lead at cylinder designates a "GOOD SEAL" would probably do same in a Rifle. Here is the conundrum, Cylinder say 2-4 inches long Rifle barrel 28 and up long ok Round not seating "GOOD SEAL" or twisting turning on way out gets stuck (sprew?) just to large for length of barrel? Becomes a barrel obstruction? I like the out of box thought you have, as well as some of the comments, I feel they were vague, "DO IT THE WAY WE DO" is to narrow minded an explanation for a broad thinker, Hope it helps I like you climb outside for a while. I search ask the hard questions, it is all in learning.