Agree with the wounded Bear scenario! Even with a Big-Bore Revolver at hand, a face-to-face shot would most likely escalate the danger.
I was in a Tent off the Foothills Parkway back in late Fall of '05. Just me, my Bike, and that .41 Tracker. Sometime around 1:00AM I hear something sniffing on the otherside of that sheer Tent Canvas. Could NOT determine what it was. No shadow. No indication of the size animal. Gun in hand, I just sat there with the thought; IF it's a Bear and he tries to inspect the inside of my tent, the first round is going to be just over his head in a effort to discourage his advancement. Bottomline; sniffing stopped but I never heard it leave. I did hear some commotion at the locked metal dumpster multiple yards away. Probably a Coon but I couldn't find any tracks near the Tent.
I agree with the Bear Spray suggestion. I'll pick some up IF I ever camp again.