Are you looking for a .416 Rigby load? What are you shooting, Speer 350s? My "go to" .416 Rigby load is 100 grains of Hodgdon 4831SC, in Norma cases, with Federal 215 Magnum Match primers, pushing either the 400-grain Nosler Partition bullet or the 400-grain Hornady FMJ. I have shot as much as 104 grains of this powder without seeing any pressure signs. If you ever go "bigger" (in our local big-bore shoots out in Montana, the .416 Rigby is probably in the middle of the pack), I load for the .458 Lott, the .470 Capstick (built on a CZ 550 action), the .500 Jeffery, and the .505 Gibbs. I also have a .600 Overkill built by American Hunting Rifles in Corvallis, Montana, that was built on a .505 Gibbs-size CZ 550 Magnum action.