While this is definitely outside my area of expertize, people seem to approve of the .338 Win mag for big bears. The .300 Win mag does not get the same hearty approval for big bear application that the .338 Win mag does. I think the .300 Win mag is a flatter shooting and hence longer range cartridge, which has its usefulness. The .338 Win mag just packs more power, albeit with less outstanding long range ballistics. People like the .338 Win mag for Elk and Moose, also, but the .300 Win mag is also commonly used for Elk and Moose, and the long range shot for Elk is occasionally encountered.