So after searching the feedback thread and getting no dedicated suggestions for the .416 Rigby or CZ 550, here's my suggestion.
The CZ 550 is a very well known and well established rifel coming in a massive variety of factory standard and custom calibers. This specific rifle I have in mind would be a older variant of the CZ 550 Safari Magnum.
The .416 Rigby is a much loved dangerous game cartridge primarily in Africa. The .416 Rigby can fire 350gr Soft point bullets at about 2500-2600fps or a 400gr round nose solid at 2400fps.
Don't let the fact that the 350gr bullet is a soft point fool you, it has immense penetrating power, more than the .375 H&H can offer at its best. The 400gr solids perform similarly to the .470 NE already in game, just with a smidge less penetration.
For ammunition stats, I think these would be appropriate.
350gr SP
• Penetration - 60
• Expansion - 25
400gr Solid
• Penetration - 85
• Expantion - 5
As for classes. Just to keep things consistent, as much as I detest the current weapon class system, I think the .416 Rigby should be the final 7-9 rifle, the one to rule them all. Irl, the .416 Rigby is good for animals that would be consistent with classes 2 and up, but that'd be 'op' in game so we'll stick with classes 7-9
Just to satisfy balancing concerns I reckon making the rifle heavier, slower to load, harder recoiling and slower to cycle than the .375 H&H in game in reasonable amounts good balancing. Also ammo would be more expensive of course.
I think this rifle as part of a weapons pack with other similar rifles or double rifles would be awesome. I'd hate to see it as a reserve rifle though because I think the .458 Lott should be saved for that roll