I'm having trouble figuring out what the ammo cases are used for, I mean I assume they hold ammo but do I need them, and do I need more than one?

Go to a reloading bench with the other accoutrements of ammo production and you can make your own bullets.

You use them to craft bullets.

I thought they were casINGS (could be mistaken) that were meant to be useful in making new rounds from spent ones at the ammo benches.

"Ammo cases" are not large carrying cases/bins, into which you toss ammunition into. Rather, it's the empty brass/plastic/etc. cases or shells, which you can scrounge and use as a component for loading your own ammunition.

A bullet is comprised of several elements... the bullet itself, the case (usually brass), a primer, and gunpowder.

darn! I'm a gun guy too! i call'um casings and I didnt make the connection! ThanKs for the replies