I usually have a pile of guns in the truck if I am out with the girlfriend...she takes her 686, I take a gp100, maybe some 1911s, at least one m14 and usually a .22...
Of course if I am by myself I am generally hiking and wouldn't want to be weighed down with all that!
Up here you are really taking your chances if you want to use much less than a 12 guage for defense in the bush. Personally I don't fear bear encounters enough to take eight or ten pounds of gun with me, so if I have anything at all, it's a .22. But if I am going far, I won't bother with any guns at all. I might cover anywhere from ten to twenty miles a day and I am not especially in to packing the extra weight in case I want to shoot something. If I am hard up for food, I usually have a half a pound worth of fishing rod on the pack, and it's supplied me with plenty of food in the bush. Also quiet!
Of course I am an all-out survivalist, as well, so I also have plenty of guns for killing zombies should the opportunity present itself. I just don't feel a big need in a wilderness survival scenario. However, I do appreciate that others feel differently and I don't think I've seen a single gun mentioned in this thread that I would not consider effective for bush survival in one way or another. I don't consider a .22 ruger pistol to be ideal for bear, but I don't consider a 45/70 guide gun to be ideal for grouse, either. You pays your money and you takes your chances!