That’s my point. Unless you’re making your own black powder and casting musket balls from ingots, you won’t be going to the store to renew stocks of shells & primers. Modern .308, 9mm, .45, etc. rounds won’t be practical in “tomorrow’s world” save only for having piles of it stashed - and if you’re going to stash piles of it, may as well get it pre-assembled; you won’t be making any reloading components from ingots.
It's a good idea to have an old smoke pole around, preferably a flintlock. You can get lead from batteries and wheel weights, you can make black powder. Flint (or any quartz rock that can be chipped to shape) is one of the most durable natural rocks, and can be found in most gravel. Good flint isn't as easy to come by, so laying up a few spare flints and a little extra powder might be a good idea. At any rate, now is the time to do it, whatever you are going to do.
I'm not suggesting the flint rifle for a short term solution to marauders, either, but just in case the problems last longer than we think they might.
For the money, .22 long rifle will take most small game up to and including Whitetail deer, if in close and well placed. A couple accurare .22s and plenty of ammo will handle the subsistence stuff, and a good pellet gun will bag squirrels and the like.