I've had this same question, and I've posted it on a couple boards. This deer hunt, I decided to see results for myself. Here's what I found.
I shot a deer this year with my 30-06. When I ran up to it, it was still alive (but dying fast). So I decided to shoot it with my 9mm XD just to see the difference between it and my 30-06 rifle. It took 3 shots to the head with my 9mm to kill it. The shots were spaced about 5 seconds apart, so it's possible that with a little more time the first shot would have done the job.
I skinned back the head to see what the 9mm had done. It looked as though the bullets all made it through the skull but got caught inside the skull (where they bounced around a bit). The brain was totally mush from the bouncing bullets. I was pretty impressed with the power.
When I skinned the entire animal, though, the 30-06 hole (especially where it exited the deer) was huge -- probably between a baseball and softball size. The trauma to the general area around the 30-06 bullet was severe.
My thoughts on what happened:
- The 9mm bullets were pretty strong. I was impressed with what they did. They expanded perfectly and worked just as they should have.
- The 30-06 bullets were three or four times more powerful than the 9mm. There really is no comparison between a rifle and a handgun. The rifle is *significantly* stronger. So while I was impressed with the 9mm, it really didn't compare to the rifle.
- If I were to meet a bear in the woods, I would certainly rather have the rifle. However, since I don't regularly backpack with my rifle, the handgun would have to do. I'd rather be shooting at the bear with anything than "playing dead" like some people say. I just don't think I could play dead unless I was already mauled pretty good.
- People have said that the handgun will just make the bear mad. Maybe so. But I have to believe that in 16-17 shots from my 9mm, at least one or two would make it into an eye socket, the mouth, or some other soft area. Would I have time to get that many shots off? Who knows.
- Bear spray is supposed to be really effective. You may just want to invest in that.
Bottom line for me -- there is something comforting (as has been said many times) about having a pistol at my side when in the hills. It is an all-around weapon against humans, coyotes, charging deer and elk, and perhaps even bears.
With *any* fight, there is no weapon that will guarantee success. You always take your chances when presented with a fight. There's always a significant element of luck and unknown variables involved in the real world. If a human *or* bear threatened my life, I'd let loose with every bullet in the mag and hope for the best.
There was a story in the news last summer about a guy back East that threw a fire log at a threatening bear and killed it instantly. There's other stories about people that hit bears with a full shotgun and the bear doesn't stop.
Sure, a rifle/shotgun is the better weapon, but I'll still take my pistol over a rock or stick. And the pistol is able to go anywhere with me.