I think this thread got started to see who would chose what firearms for a worst case scenario, but then went viral into considerations of what might happen and how prepared we are. Me, I ain't prepared at all for such stuff. I've got no supplies stored away and no horde of ammunition or anything else.
I think we fool ourselves to believe survival is possible when the production of everything shuts down. Some of us may be young enough and strong enough to do without modern medicines and doctors and cars and cleanliness, but still, you can't do so for as long as you might think. Whatever we have saved underground or anywhere will soon be depleted. Government functions will cease. No police, no emergency services, no one to mend our broken bones. or come to our aid. No one will even know we need aid. No phones. No computers. No control over the reality of ever increasing vermon such as rats and roaches. Money will be useless. Your children and grandchildren will die from the slightest conditions that can be fixed now. No hospitals. The majority of the population will turn in upon itself and die. You can't possibly hold out against total chaos. Sure, the more you put back for such an emergency the longer you can live, maybe. No antibiotics. Nothing to do for the slight infections that will turn deadly. No realistic preparation will keep you alive for very long. Stay put or move, it makes no difference. The gun(s) you have within reach will be insufficient; someone will have more and bigger guns.
Back to the original point, if I had to live off an unpolluted landscape, I think I'd chose a rifle capable of taking food and taking out raiders at long range. I would not consider a handgun. Handguns are for those who cannot carry a rifle due to society's restraints. When the rules of society expire, I want a rifle, or a shotgun. Revolvers and pistols are popular now because they can be hidden. We won't be interested in hiding weak weapons when the worst happens. When the worst happens, all the guns and ego and big ideas we hold now will fall away even before death arrives to steal our loved ones. We will degenerate into a filthy mire of trying to live off what someone else might have that we can take. That's the reality of a failed society or a catastrophic failure from any other source. The belief we can shoot our way out of it is fantasy at best.