Oregon Revised Statutes Chapter 166 § 166.266 — Sale,

Sale, transfer or possession of firearm without serial number. (1) A person may not knowingly possess, offer for sale, sell or transfer a firearm unless the firearm has been imprinted with a serial number by a federally licensed firearm manufacturer, importer or dealer, or a gunsmith with a federal firearms license, in accordance with federal law. (2) This section does not apply to: (a) Antique firearms; (b) Firearms manufactured prior to October 22, 1968; (c) Firearms rendered permanently inoperable; (d) The sale, offer to sell, or transfer of a firearm to, or possession of a firearm by, a person licensed as a firearm manufacturer, importer or dealer under 18 U.S.C. 923; or (e) A gunsmith taking possession of a firearm for the purpose of imprinting the firearm with a serial number in accordance with federal law. (3)(a) A violation of subsection (1) of this section constitutes a Class B violation. (b) Notwithstanding paragraph (a) of this subsection, a violation of subsection (1) of this section is a Class A misdemeanor if, at the time of the offense, the person has a prior conviction under this section or ORS 166.265 or 166.267. (c) Notwithstanding paragraphs (a) and (b) of this subsection, a violation of subsection (1) of this section is a Class B felony if, at the time of the offense, the person has two or more prior convictions under this section or ORS