Sort-of memes that are cracking you up at the moment

doesn't a bullet use a small amount of gunpowder, which ignites / combusts, and therefore needs oxygen

Firearm propellants, whether gunpowder or modern (post 1886) nitro type, contain their own oxidiser. The useful combustion all happens inside the gas-tight chamber, which is a brass or steel cartridge case in modern (post about 1860) small arms.