Not that a good rifle or shotgun would'nt be handy but I'd be more concerned about:
Food
Water
Shelter
Medicine
Clothes
Transportation
Electric power
How long are we talking, a week, a month, a year, for the rest of my life? Also, I think if I was defending my home from any, even poorly organized, mob I'm SOL. One bottle of gasoline with a lit rag and the house is gone, me too. If you're talking fighting against trained individuals/soldiers than I'm probably going to measure my remaining life in seconds. No way I could stand up to a trained force or individual. I'm thinking hunker down and wait it out.
When I think of SHTF, I think in terms of months/years. I would head for the hills. As far from cities and towns as I could get. Then you can have a relatively clean water supply, and plenty of food. You are unlikely to cross mobs of people since most people will likely head for cities and towns. No soldiers looking for you in the woods, either.