Circumstances alter responses. If no danger from human contact, in this area a .22 rifle would be adequate, even for deer, light, easy to carry with strong likelihood for finding available ammo. Even if human threat is involved, still to be considered if only threat from one or two individuals. In the Northwest, grizzly activity to be considered and a larger caliber might be wise. Altho a short barreled pistol is the best response to close grizzly threat, a rifle would be a better choice for multiple uses.
If human combat likely in groups, I'll stick to my AR15...lot of ammo around for that also and will serve for hunting and defense although in that scenario the best defense is to remain invisible or to join a large organized group and hope it doesn't turn on you. If a Katrina type issue, the AR if in populated area, and perhaps a compact .45 if only the occasional threat is likely. I wouldn't like to depend on a short barrel 9mm in a disaster situation...too limiting in terms of response to various situations.
If only one weapon of any sort is allowed, in the woods I'd have to stick with a knife for survival...with that one can form other weapons of a more primitive nature...really really hard to whittle a bow with a Colt .45.
