I carry a 40 a lot when I'm out also, but I've never considered it a bear defense gun. As a bear defense gun against your average run of the mill black bear a 40 would work, just keep pulling the trigger. A heavy long barrelled 44, 480 or other similar guns are great hunting weapons but for up close and personal work I can't see how you would have time to unholster and bring it into action.

However, my best advise is to use common sense and beware of your surroundings. Most black bears scare easily just by yelling and waving your arms, I've actually done this to several bears and it works.I've even thrown a half empty water bottle at one that got a little too close during squirrel season when I was only armed with a single shot 22.