I'd take the .300 Winchester Mag, and load it up with 200 or 220 grain Partitions or Xs. I Shot my Dall ram at over 500 yards-there was no way to get closer. A 375 wouldn't have worked in that situation. The .330 Winnie with good bullets is a match for any Grizzly. Perhaps a better compromise would be a .338 or .340 Weatherby.