I agree, the .416 would be a good choice, but for some reason, I've always had a desire for a .404 personally. It is capable of almost 2,400fps with 400gr. bullets in a good bolt gun with maximum pressure-type loads, and that makes it more than suitable for anything I would ever be shooting at. That makes it capable of duplicating the .416 Rigby factory ammo. Factory level ballistics for the .404 Jeffery are about the same as the .450/.400's and the resulting reduced recoil makes for a much more pleasant round to practise with. Heavy kickers usually are ignored when time comes to practise, while with less recoil the experience gained by practising with the .404 could 'save the day'.
: For factory level ballistics, the .404 uses 30gr. LESS powder than does the .416 Rigby. That makes a substancial difference in felt recoil.
: I'm getting old, and the recoil is wearing on me. I'm also an avid shooter, and must shoot a lot. It's the way I live - to shoot and fish.