I know I'm not the most dexterous man on the planet, but there is no way I could hunt with my 30.06, a shotgun full of slugs, and my pack.
When bear charges you it's not going to be from 500 yards off where you can calmly get you crap together. Someone said with bear spray you'll have to be fairly close. Yeah, you'll be fairly close and very quickly. I stumbled on a black bear this last year hunting. We noticed each other at the same time. No more than 20 yards apart. It was actually pretty funny, you could tell we both scared the hell out of each other. The bear grunted and took off through the forest like a wrecking ball. I've hunted bear but this face to face left me shaking pretty good. I couldn't imagine what would have happened if I would have actually had to try and get a kill shot from 20 yards at a charging bear.
I agree, and perhaps should have worded my post a bit better. I certainly distinguish between carrying for hunting and carrying for protection/defense. When working in the bush I carry a shotgun most of the time, but this is strictly for defense against an attack from a bear, the rifle stays in camp. While hunting I would certainly never bring both rifle and shotgun.
I've had black bears charge on several occasions, and it can certainly be intimidating, luckily on each occasion there was ample time to react (they were spotted well before charging). I have seen a bear "charge" from about 400m out (or is it simply called "running" if they are that far away), it spotted me, stood on its hind legs, sniffed the air, then ran at me full speed, it closed that distance surprsingly fast! I fired two pen bangers at it when it was about 50m out, which scared it away temporarily, giving me plenty time to radio the helicopter to drive it away.
I've worked around grizzlys in Alaska but luckily never had a real run-in with one. Most of the local guys I worked with there opted for 44mag revolvers, with Ruger and Taurus the most popular choices. I have carried a revolver in the past, but in Canada the government keeps making it harder and harder to get the required carry permit (they are now very region specific with short validity periods, and they have just implemented a timed range proficiency test that must be passed before permit issuance).
Polar bears are the ones that really scare me as they are such effective predators, chances are I would never have a chance to get the shotgun off my pack in time, luckily I've not run into one on the ground face-to-face, I've seen plenty from the relative safety of the helicopter. The polar bears I have seen were not scared by the helicopter noise like black and brown bears, in fact I've seen polar bears stand on their hind legs and try to swat the helicopter out of the air! Luckily they spend most of their time out at the pack-ice hunting seals and not wandering around inland looking for humans to feed on!
If I was going hunting
specifically for Grizzly/Brown/Kodiacs/Polar bear I would opt to buy a larger calibre rifle, perhaps a .300 win mag or a 375 H&H.