Your profile says that you're from Utah. I'm assuming that you want this rifle as a carry around gun for medium to large game hunting (mulies and elk).....
I have a 30-378 Weatherby Mark V and consider it to be perfectly suited to the type of hunting that is encountered in the west.
I've had it for 3 years now and have shot it very little because it's a horrible throat burner but it's a HUNTING RIFLE and I only shoot it about 60 rounds per year. It's probably only good to about 600 rounds before throat erosion starts degrading accuracy.
I know that you were asking for sub 30 caliber recommendations but when you want to carry enough energy way out there.... 30 caliber is a great choice and IMO you'll have a hard time delivering enough accuracy with adequate energy with 6mm or 6.5mm at long ranges.
btw... These rifles come with a very good factory muzzle brake
that tames the recoil to quite manageable levels but is horribly loud and you absolutely should never, ever, shoot it without very good hearing protection.
I compare the felt recoil with this rifle to my Remington Model 7 chambered in .308 (no brake)