The actual deminsions of a bullet are a moot point. Get a bullet design with a high enough B.C. and S.D and put it in a case that can push it fast enough. Then, find a barrel that will shoot that bullet well. Heck, I'd like to be a rich old fart that could take a .10 caliber bullet in the 60-100grain and redefine what people think could be done. Varmints and paper everywhere would shudder at a 600yard 3" point blank range Any idea what type of money it would take to head up a project like that? IT WOULD BE UNREAL!!! You'd have to start from the ground up. No one I know of makes bullets in .10"; barrels in .10"; dies in .10"...and then I suspect you'd have to design a completely new case with a taper at the base and not just the shoulder. That would probably necessitate a new magazine design...or a new gun based on a rotary magazine. Then...I doubt I wouldn't get the itch to develop some new powder just for it. (realistically someone could start with the .17 remington and go from there.) BUUUTTT I'm just rambleing and trying to make peice at the same time. Sorry for high jacking the thread.