; and (ii) in the case of a rifle or shotgun, includes the barrel of the firearm; and ; and (C) by striking subparagraph (C) and all that follows through the end of the undesignated matter following subparagraph (C) and inserting the following: (C) 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. ; (3) in paragraph (3)— (A) in the first sentence, by inserting , including a prototype, after of a firearm ; and (B) by striking the second sentence; and (4) in paragraph (5), by striking shall not apply to any firearm which and all that follows and inserting the following: “shall not apply to— (A) any firearm received by, in the possession of, or under the control of the United States; or (B) the manufacture, importation, possession, transfer, receipt, shipment, or delivery of a firearm by a licensed manufacturer or licensed importer pursuant to a contract with the United States. .