I use the 250 grain SGK exclusively in my .375 Weatherby.
It is my bear gun. I run the 250's at 3060 fps and they are HELL for tough !!! One old boar, in particular presented a classic Texas heart shot at 50 yards. The Sierra all but came out his chest, wading nearly 7 feet of bear meat.
Cow bison ribcage shot ?? You BETCHA !!!!
Good to hear about the 250 Sierra, I was about to recommend at least a 270gr Hornady, with 300gr Swifts or Partitions for a little extra, although the bison I've killed have been with 530gr paper patched bullets from a Shiloh Sharps rifle.
