I've only shot one "charging" animal, a 245-pound feral boar which was going to die soon from my previous shot. One 150-grain Speer Grand Slam from my .270 Winchester through the shoulder stopped everything.
The brown bear guides and African PH's I know (and trust) best prefer cartridges from .375 H&H up. They say cartridges above .40 in caliber tend to slow charging animals enough to get in another shot, but even with really big rounds the only way to be certain of literally stopping a charge is to hit the central nervous system.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
