I agree with 450, and I live here, doing a lot of field work in the summer on the backside of nowhere along salmon streams. I have carried shotguns, I've carried handguns and I've carried rifles. My current long arm for bear protection is a 411 Hawk stoked with 400 grain Woodleighs.

Just any old slug doesn't cut it. I've seen bears wounded and get away from folks using the "Foster" type slugs. They are just too soft and density is too low. James Gates at Dixie Slugs is supplying some Paradox slugs that I would feel comfortable carrying.

I had rather rely on a rifle rather than a shotgun if possible. If you are really concerned, check out James' Terminator or Predator slugs, or get a 458, cut the barrel to 18-20" and load with some 500 grain premium bullets.

For this Alaskan, I prefer a rifle.

By the way, Professional guides here in Alaska that guide for bear carry rifles, not shotguns, for backup. 416's and 458's are the norm. I do not know a single one that carries a shotgun for that purpose.