Shotguns have no rifling in their barrels. They fire multiple little pellets at once. Rifles have spirals bored into the barrel. This is called rifling. They fire a single bullet. Any rifle action is compatible with shotguns, but only some are practical. Pump action, semiautomatic, break action, lever action and pump action are good and practical for shotguns. Rifles are best suited with bolt action, semiautomatic, break action and lever action.