I've often heard you'd better have at least a .41 magnum if you have to drop a large bear--anything else just p*sses them off. Hi capacity magazine was a big help. Keep shooting until the threat is eliminated.
https://www.americanhunter.org/articles/2016/8/10/alaska-outfitter-defends-fishermen-from-raging-grizzly-with-9mm-pistol/#.V6uFoJylXX0.facebook