ORS 166.266: 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 166.265 or 166.267.

      (4) A person convicted of any offense under this section shall forfeit the firearm.

      (5) As used in this section, “prior conviction” includes a conviction for a violation offense.