Someone is making 5mm Remington ammo again. Aguila?
I would choose...
.425 Wesley Richards
6mm Lee Navy
.250 Savage (no, it's not really obsolete, but it is slipping, and that's a shame because of what a wonderful cartridge it is)
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.