The zombies are hoarding them for the apocalypse. Preferred caliber is 300Blackout, of course. When the night of the living dead comes, they won’t have to stumble around hoping to snag a slow human. Why try to catch the brain carrier when they could knock the brain right out of the skull with hydrostatic pressure and then savor at leisure. Ten foot tall zombies with guns. There ought to be a law or something!