RE: 416 Rigby vs. 416 Rem. Mag
It will cost a lot less to own and operate the Remington version. However, when loaded to the same levels, (400 grain bullet @ around 2400 FPS), the Rigby operates at a lo lower pressures and temp., so might be a better round for real hot climates> Plus, it can be loaded up toward the level of the .416 Weatherby, if desired.
Keep yore powder dry!!