For big bear with a 300 Win Mag I would use a 200gr Swift A-Frame.
I'm loading up some right now for velocity testing. I need 2900-3000 fps, but the best I could get with the IMR 4350 that I've got loads of was @ 2800 fps. I finally got a few pounds of Ramshot Magnum and Accurate Magpro as well as a few hundred 200 grain A-Frames, so the testing restarts. The 300 WinMag Tikka has become my favorite rifle. I've been shooting 200 grain Accubonds at caribou over the past 15 years, but since caribou hunting has gone the way of buffalo hunting in the late 1800's, it's back to moose. The Accubond would do fine on moose, but I want to try the A-Frame just for the novelty of it.
