You’re speaking of today’s world.
We’re talking of tomorrow’s world where there won’t be any stores to go to and buy your needs. You’ll have to do it from scratch.............
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.