In a wrol/shtf scenario, how would you go about renewing your supply of ammunition? I know in the old west days they made cartridge casings out of paper, but what about primers and powder? Without a stable supply of sulfur it'd basically be impossible to create gunpowder, and I don't even know how to create a shock-sensitive explosives for the primers, let alone how to make them renewable.

100 years after we nuke ourselfs are we going to be able to make new ammunition or will we be returning to crossbows and the like? Modern ammo supply requires WAY too much infrastructure for people to be able to get ammo should the supply-chain fail.