Where do I get empty casings

I saw in explosives it said to combine it with empty casings to prime them

Uhhh there are no empty casings… im sorry but i actually have no idea what you’re talking about lol

Its in the description of the explosives

Those aren’t in the game anymore. Instead they’re used for Explosive Charges: 15 explosives + 1 Flare = Explosive Charge.

Aw that sucks