The idea is great, but there is one minor problem: The 45 basic case is MUCH bigger than the 45 Colt, in fact about all they have in common is the "45" in the name. The rim diameter on the 45/70 is .608" while the 45 Colt is .512". I think your theory might hold water if you could find brass long enough.I'm not so sure about the use of the .410 hulls. The walls on the hull would be so thick that you'd have to use a 44 or smaller bullet to make them chamber. Then Youd have a bullet so small they'd bounce down the bore and you're accuracy would really go to pot!!!