The concern is not shooting and hitting a bear standing, bluffing or charging. They have been popped with 9, 45s, all sorts of calibers. Its not that any firearm or caliber will stop a bear, its about a bear on top slapping you around, chewing, stomping on you. This is where semi just make a poor choice as they can come out battery and not fire with a greater chance of fur, dirt, clothing etc jammed in the action, push the muzzle of that Glock into the chest, neck of a bear that is on top mauling and it will come of battery and not go bang, that is a fact semi will not go bang out of battery.
Everybody seems to have this notion that a bear stands erect 20 yards away with mouth open in a nice clean open area. If you think so, sorry to say your sorely mistaken. Bears are in head high grass, thickets so dense sunlight has a hard time finding its way through, all sorts of different terrain and this is where they are most dangerous, they cannot see what is there only by sound and smell.
Blast with spray will most likely send the bear into what just happened and you can back out slowing. I prefer bear spray as my first line of defense for bear encounters. I prefer 12ga as a stopper but very hard to tote a long gun and do things, it gets in the way. I have set my shot gun down to fish, gather wood. gather berries, walk down to the creek to get water, only to see mr bear there and realize I left my shot gun laying or leaning a long way away. I have slithered through thickets so dense the barrel of shot gun and rifle was tangled every second in the thicket. Hunting with my cousin just this very thing, on hands and knees and belly and backs, my cousin said bear, we stared right into a massive beautiful grizzled fur and eyes staring right at us, what to do, can not back out, bear is not backing out either just those eyes staring back, can not aim rifles as they are tangled up, we could unholster hand cannons and take a bead.
A full hell bent charge, sorry but there is no time to draw a any weapon so caliber is not that important. What is, being able to draw what ever firearm you have by either hand, one hand may be in the bears mouth,under a paw, under you body, etc muzzle up the bear so short barrel is best and pull the trigger until it stops going bang.
I was charged and knocked down by a young brownie, I was in head grass, heard the campraiders just a split second before hearing something coming from 4-5 oclock. By the time I spun my head around, bear hit my legs knocking me down, all I saw was brown blur. I was lucky being a young bear or he may have been scared that I was a dominate male. He knocked me down and kept running jumping up of a large rock where he began to survey. He sniffed, popped and stomped. I played dead until he left.
I have been bluffed numerous times down to 10-12 yards but most of them 15-20 yards or so. Had bears walk into camp, slither out of the darkness and appear, no warning, some stopped, others kept walking, others ran off seeing humans and or blast of spray. In the backcountry. Had bears see me and run. Had bears see me and stop. Had bears see me and bluff. Had bears see me and go back to eating grubs. Bears are unpredictable and every encounter and every bear is different. Its best to put odds in your favor at the highest degree possible.
Certification for bear guard requires hits on the charging bear target. The cert was, a target set up on pulleys and cable pulled by a 4 wheeler from 25 yards from the side and behind with the instructor yelling bear and then all sorts of confusion was instilled into the cert. Yea I know, we all are one hole dead eye sharpshooters but the cert was very hard and stressful for everyone to include the instructors running the drills, hand magnums and 12ga.
