Firearms must be serialized as follows:

1. (1) Any individual or entity in possession of a previously manufactured or assembled firearm, must serialize said firearm by October 2, 2026, unless the firearm falls within one of the enumerated exemptions listed in 501 CMR 20.12 or has a valid serial number.
2. (2) Any individual or entity that manufactures or assembles a privately made firearm must obtain a unique firearm serial number from DCJIS prior to manufacture or assembly and serialize the firearm frame with the obtained serial number during manufacture or assembly.
3. (3) Lawfully owned firearms imported or acquired by new residents moving into the Commonwealth or acquired by heirs or devisees through distribution of an estate shall be serialized within 60 days of import, acquisition, or inheritance.
4. (4) Lawfully owned firearms imported or acquired by licensed firearms dealers, gunsmiths, distributors or manufacturers shall be serialized within seven days of import or acquisition.