Although they usually use specialized match ammo which they load at home.

Self-defense weenies need a few rounds on hand, and a box or two when they practice at the range. This is my category, I buy a hundred rounds (a couple of boxes)or so per piece every year, and keep a hundred or so in reserve.

Hunters probably need the same amount, depending on the kind of game they go after.

The guys who are expecting a foreign invasion or a Communist coup d'etat can never have enough. This is who the NRA is now marketing to. The other shooters pretty much have all they need, both guns and ammo. That market is saturated. The minutemen/militia/patriot guys, and the criminals never feel they are sufficiently armed.

Check out the gun porn at your local supermarket magazine stand. This isn't Field and Stream stuff any more, this is an arms race. And like all arms races, they are very profitable for arms merchants. These are the same guys who used to sell repeating rifles to the Sioux. The combination of fear, ideology and profit is deadly.