I was in New Orleans
I lent my neighbor my 870 with #4 police loads.
I lent another neighbor my revolver.
I lent another neighbor a 1911 9mm.
I kept my MC Operator on my belt with 8 8 rounders and 6 10 rounders.
I had the AR in the house against the door, when outside, I had my socom 1 with the holo sight chambered and on safe either on my neck or next to me. Icarried the rifle for about a week until the heavy looting and shooting went away. I left to go to IDPA nationals and when I got back, the town was much more ghostly- I am an engineer and had a permit to be back.
Cops never said a word, but I only once go out and venture. That one time, they wanted me to be armed. I served Nat Guard coffee from my porch made either off of generator, or fire. I don't know why I stayed, I had places to go and my job moved to somewhere else temporarily. I just needed to be here.
In retrospect, the challange is what weaponry is used is always there. THe difference between SHTF and a disaster where the thinly veilled welfare state created by both short thinking libs and cons who want to cash in on votes from welfale mothers collapsed. Being of the independant thinking but similar ilk, I think we all fantasize about the SHTF scenarios and liken it to the Nazi siege of russian cities, where we lay in our own feces waiting for that one crisp head shot of the colonel or some post apocolyptic "Day After" where we kill hords of mutants hell bent on getting our MREs.
In something like Katrina, I saw the "good guys" trying to build whatever community one could- guess what happens if you fall off your roof trying to put a tarp on it. You stay on the ground until you die- or crawl for eight miles with a broken back. The bad guys already had a community- and it was well though- these were not blood starved zombies, they had the intellegence to steal a front loader from a construction site to remove a steel grate gate from a pharmacy to get the drugs. In my venture, I went in and saw shelf full of water and canned soup, but the enitre pharmacy was cleaned.
Long story short, there is no one good rifle. I train with my socom, so I know how to clear jams and I know how to double tap when needed, and can reload. Tactically I am quicker with the AR, but comfort level I like my 308. I would have rather been in a boat helping people get off their roofs or been pressed by the Army Corp to get pumps running (my day job) but the Army is very sensitive about accepting civilian help. Once the General got boots on the ground, there was little to do here except get the wet stuff out of the house and clean the refrig.
Good luck, but go classic if at all.
