In any long-term disaster or survival situation, you must plan on defending yourself. There are lots of people who refuse to store any supplies, but who plan to take what they want by force, when things get bad. If you have built yourself a retreat and stocked it with supplies, there is a very good chance that some of these types will eventually discover your location, and try to take what you have. To prepare a defense against such an attack, you need a supply of guns and ammo, but you also need tactics which will put the odds in your favor, even if you are badly outnumbered.