PEN § 23920

(a) Except as provided in Section 23925, any person who, with knowledge of any change, alteration, removal, or obliteration described in this section, buys, receives, disposes of, sells, offers for sale, or has in possession any pistol, revolver, or other firearm that has had the name of the maker or model, or the manufacturer’s number or other mark of identification, including any distinguishing number or mark assigned by the Department of Justice, changed, altered, removed, or obliterated, is guilty of a misdemeanor.

(b) Except as provided in Section 23925, any person who, on or after January 1, 2024, knowingly possesses any firearm that does not have a valid state or federal serial number or mark of identification is guilty of a misdemeanor.