meh, I might be underestimating the crazies on one side of this argument..
ETA: But then again, in general I think the South would be a blood bath after something like this happened. Way to many hot heads with no reason to not go crazy with their 40 guns they have stockpiled.
Generally speaking it's not the guys with 40 guns you'd really have to worry about in the end of civilization scenario. They are generally going to be the most gun safety conscious and least likely to go nuts. It's the ghetto thugs with 1-2 guns that would be far more dangerous.
Not that there wouldn't crazy arse mountain man style miltia people popping up, but your typical person who owns 10-20 guns is just into hunting, fishing, and/or target shooting for the most part. They'd probably wind up helping protect farming establishments and small towns that developed after.
I will say one thing for sure, any of the large cities would be complete chaos in such a situation and I'd be getting the hell out of Phoenix ASAP (which would suck balls, cause it would take me one hell of a long time to bike across Texas).
And yes, given our back and forth it was kinda apparent most of your interaction with guns was via TV and movies.