; or (B) manufacture a firearm with the ghost gun. . (3) Requirements Section 923(i) of title 18, United States Code, is amended by adding at the end the following: The serial number shall be engraved or cast in metal or metal alloy and sufficient to identify the firearm and the manufacturer or importer that put the serial number on the firearm. . (4) Penalties Section 924 of title 18, United States Code, as amended by this Act, is amended— (A) in subsection (a)(1)(B), by striking or (w) and inserting (w), or (aa) ; and (B) in subsection (d)(1), by striking or (k) and inserting (k), or (aa) . (b) Modernization of the prohibition on undetectable firearms Section 922(p) of title 18, United States Code, is amended— (1) in the matter preceding paragraph (1), by striking any firearm ; (2) in paragraph (1)— (A) by striking subparagraph (A) and inserting the following: (A) an undetectable firearm; or ; and (B) in subparagraph (B), by striking any major component of which, when subjected to inspection by the types of x-ray machines commonly used at airports, does not generate and inserting the following: a major component of a firearm which, if subjected to inspection by the types of detection devices commonly used at airports for security screening, would not generate ; (3) by striking paragraph (2) and inserting the following: (2) For purposes of this subsection— (A) the term detectable material means any material that creates a magnetic field equivalent to or more than 3.7 ounces of 17–4 pH stainless steel; (B) the term major component , with respect to a firearm— (i) means the slide or cylinder or the frame or receiver of the firearm; and (ii) in the case of a rifle or shotgun, includes the barrel of the firearm; and (C) the term undetectable firearm means a firearm, as defined in section 921(a)(3)(A), of which no major component is wholly made of detectable material; ; (4) in paragraph (3)— (A) in the first sentence, by inserting , including a prototype, after of a firearm ; and (B) by striking the second sentence