Ghost Guns in Massachusetts: What the Law Requires

Massachusetts General Laws Chapter 140, Sections 121C^[1] and 121D^[2], added by Chapter 135 of the Acts of 2024^[3], establish criminal penalties for unserialized firearms and regulate equipment capable of manufacturing them. These provisions represent a significant expansion of the Commonwealth's firearms regulatory framework.

What Is an Untraceable Firearm

Under Section 121 of Chapter 140, an untraceable firearm (commonly called a ghost gun) is defined as a firearm, rifle, or shotgun, including a frame or receiver, that lacks a unique serial number engraved or permanently affixed by a licensed manufacturer. The definition includes firearms assembled from parts kits, manufactured using 3D printers or CNC milling machines, or otherwise produced outside the licensed manufacturing process.

The term also covers "unfinished frames or receivers," meaning partially completed components that can be readily converted into functional firearm frames or receivers. This is significant because the federal regulatory framework historically treated certain completion percentages (such as the so-called "80% lower") as non-firearms. Massachusetts law does not recognize that distinction.

What Is Prohibited

Section 121C makes it unlawful to:

Possess a firearm, rifle, or shotgun that does not bear a serial number
Manufacture, assemble, or cause to be manufactured a firearm, rifle, or shotgun without a serial number
Sell, transfer, or distribute an unserialized firearm or unfinished frame or receiver
Remove, alter, deface, or obliterate the serial number on a firearm (this prohibition existed before Chapter 135 under Chapter 269, Section 11C, but Section 121C reinforces and extends it)

The prohibition applies regardless of whether the person holds a valid LTC or FID.

Serialization Requirement for Existing Unserialized Firearms

If you lawfully possessed an unserialized firearm before October 2, 2024, Massachusetts law requires you to apply to the Department of Criminal Justice Information Services (DCJIS) for a serial number. DCJIS will issue a unique identifier that must be permanently engraved on the firearm.

The process is handled through the Firearms Records Bureau. Contact DCJIS at the information provided on the firearms services page^[4] for current application procedures.

Failure to serialize a previously lawful unserialized firearm constitutes a violation of Section 121C.

3D Printers and CNC Milling Machines

Section 121D creates a separate regulatory framework for equipment capable of manufacturing firearm components. This section applies to 3D printers, CNC milling machines, and any other equipment that can be used to produce a firearm, rifle, shotgun, frame, or receiver.

Under Section 121D, any person who possesses a 3D printer or CNC milling machine capable of producing firearm components must:

Not use the equipment to manufacture a firearm, frame, or receiver without a federal firearms manufacturing license
Comply with any registration or notification requirements established by EOPSS regulations
Not distribute digital files or instructions designed to produce a firearm, frame, or receiver using such equipment to any person who is not a licensed manufacturer

The law does not prohibit owning a 3D printer or CNC mill. It prohibits using that equipment to manufacture firearm components without proper licensing, and it restricts the distribution of manufacturing files.

Criminal Penalties

Section 121C itself states the serialization prohibitions and requirements but does not contain a criminal penalty clause. The penalty for possessing or controlling an untraceable firearm is set in MGL Chapter 269, Section 11C: imprisonment for not less than 12 months and not more than 2.5 years. Possession or control of an untraceable firearm is prima facie evidence of a violation. Other firearm-offense penalties under Chapter 269, Section 10 may also apply depending on the conduct.

Violations of Section 121D regarding 3D printer and CNC mill misuse carry penalties as established in the section, including fines and imprisonment.

These are criminal penalties, not civil infractions. A conviction results in a permanent criminal record and automatic disqualification from holding any Massachusetts firearms license.

How This Differs from Federal Law

Federal law also regulates unserialized firearms. The ATF's 2022 Final Rule (27 CFR Part 478) requires that frames and receivers sold by licensed dealers bear serial numbers and that buyers pass background checks. However, The U.S. Supreme Court upheld the ATF ghost gun rule in Bondi v. VanDerStok, 23-852 (March 26, 2025), in a 7-2 decision. The federal ghost gun regulation is now settled law.

Massachusetts law is broader than the federal framework in several ways. It criminalizes simple possession of an unserialized firearm, not just commercial sale. It regulates the equipment used to manufacture firearms, not just the finished products. And it does not recognize any completion percentage threshold below which a frame or receiver is exempt.

A person in compliance with federal law may still violate Massachusetts law. The state standard is the one that applies within Massachusetts.

Connection to Other Massachusetts Laws

Storage (Section 131L): An unserialized firearm is still a firearm for storage purposes. However, possessing it at all is already a separate criminal offense, so storage compliance does not legalize the underlying possession.

Transfer reporting (Section 129C): All firearms transfers must be reported through the eFA-10 system. An unserialized firearm cannot be lawfully transferred because it cannot be registered.

Licensing (Section 131, Section 129B): Holding a valid LTC or FID does not authorize possession of an unserialized firearm. The serialization requirement exists independently of licensing.

Untraceable Firearms (Ghost Guns) in Massachusetts:
What the Law Says