My new calibers / cartridges

[DubiousDan]

Or, the 45-70, which is a 45 caliber that held 70 grains of black powder.

Then there's the 38-40 that's 38 grains of black powder and a 40 caliber bullet.

Grab a copy of "Cartridges of the World". Originally by Frank Barnes but I think someone else is doing it now. I found it interesting and informative. There's a great chapter on obsolete cartridges.