I think that I found a 500 mag load that I like.

[the terminator]

This load delivers just over 2200 lbs of energy, at the muzzle, and is a medium pressure load. It far exceeds the .454, for comparison, but is at a much lower pressure due to the larger case capacity. I have a box of 370 grain bullets here in the drawer, now I've got to stop by and pick up a new can of powder.

370 GR. CPB LGC Hodgdon H4227 .500" 2.020" 40.0 1688 38,700 PSI