1. Short title This Act may be cited as the Mass Shooter Prosecution Act of 2023 . 2. Mass killings using machineguns or covered semiautomatic weapons (a) In general Chapter 113B of title 18, United States Code, is amended by inserting after section 2332i the following: 2332j. Mass killings using machineguns or covered semiautomatic weapons (a) Whoever kills 3 or more people in a single incident using a machinegun or a covered semiautomatic weapon in a circumstance described in subsection (b), shall be imprisoned for any term of years or for life. (b) A circumstance described in this subsection is any one of the following: (1) The mail or any facility of interstate or foreign commerce was used in furtherance of the offense. (2) The machinegun or covered semiautomatic weapon used in the commission of the offense was transported in interstate or foreign commerce. (3) The perpetrator traveled in or caused another to travel in interstate or foreign commerce in furtherance of the offense. (4) The offense occurred within the special maritime and territorial jurisdiction of the United States. (5) The offense otherwise occurred in or affected interstate or foreign commerce. . (b) Definition Section 2331 of chapter 113B is amended— (1) in paragraph (5), by striking and at the end; (2) in paragraph (6), by striking the period at the end and inserting a semicolon; and (3) by adding at the end the following: (7) the term covered semiautomatic weapon means— (A) semiautomatic rifle that— (i) has a magazine that is not a fixed magazine; and (ii) does have any one of— (I) a pistol grip; (II) a forward grip; (III) a folding, telescoping, or detachable stock, or is otherwise foldable or adjustable in a manner that operates to reduce the length, size, or any other dimension, or otherwise enhances the concealability, of the weapon; (IV) a grenade launcher; (V) a barrel shroud; or (VI) a threaded barrel