Banning Unlawful Machinegun Parts Act of 2018 or the BUMP Act This bill amends the federal criminal code to generally prohibit the import, sale, manufacture, transfer, receipt, or possession of a device that is primarily designed, or redesigned, to increase the rate of fire when attached to a semiautomatic firearm; a device, part, or combination of parts that is designed and functions to increase the rate of fire of a firearm; or a semiautomatic firearm that has been modified to increase the rate of fire. Additionally, the bill amends the Internal Revenue Code to add semiautomatic firearms to the list of firearms subject to regulation under the National Firearms Act.