Ok, so there's casings, primers, etc.

However, there are also case boxes, jars, etc. I still don't know how to use them. Are these meant to be used by those who have the Hand Loader perk?

Drop the boxes and jars on the ground and pick them up. They're intended to be bulk supplies but only work (unpack) when you pick them up. Drop a jar of power, pick it back up and it becomes normal powder for reloading.

I'm guessing they were originally intended to be included as loot but didn't quite make it.

That's.... weird. Well, thanks for the info!

was wondering what those did since they never showed up in the crafting menu. thanks.

I think they're just not working correctly. Sometimes, after shopping for it, you get credited with the ingredients instantly. If you don't, like plague said, drop them and then pick them back up.

where do I get lead from? or is that only obtainable threw breaking ammo down?

You can break scrap metal into 200 lead per bit.