Grizzly bears are notorious for being difficult to kill with a firearm. This has been documented all the way back to Lewis and Clark. Some science goes into the choice of firearm for killing a grizzly and people who think they are going to stop one with a hand gun are ignorant. Two, three years ago there was an incident on the Montana Idaho border where a hunter encountered a grizzly while hunting elk. He unload his 30/06 rifle on the bear. The bear killed him and left. From what I read bear spray and other maneuvers are way more effective.