Basically, we're tired of the Solokhin 7.62x54R being alone in it's class. It's a good gun and works beautifully but having literally one weapon in that category is boring.
Yes, we have the hudzik's 3-7 ammo type and the Moradi .44 lever action but they are both dlc and situational. I've seen tons of people interested in this idea so I'm going to list the calibers I see recommended for this most often.
BASE GAME
Huntsman .270 (all variants)
Whitlock .30-30
DLC
Martensson 6.5mm
Johansson .450
I'm not suggesting the Fors Elite .300 (7.62x35mm) for this class range as it's severely underpowered for the majority of class 6 and 7 animals.