Protecting Legal Firearms Ownership Act of 2023 This bill states that any firearm or firearm attachment that was lawfully manufactured before the effective date of a new rule or regulation shall be grandfathered and shall be permitted to be sold, transferred, and possessed in accordance with the previous rule regime. The bill specifies that the manufacturing date of a firearm or firearm attachment shall be determined by the serial number recorded on the firearm or firearm attachment, or any other legal method of recording the date of manufacturing, including packaging.