Untraceable Firearms and Serialization Requirements:
Sections 121C and 121D

Chapter 135 of the Acts of 2024^[1] introduced Sections 121C^[2] and 121D^[3] to address the growing concern over untraceable firearms.

What Is an Untraceable Firearm?

Under the updated definitions in Section 121^[4], an "untraceable firearm," commonly known as a ghost gun, is any firearm, including a frame or receiver, that lacks a serial number assigned by a licensed manufacturer or importer, or that has had its serial number altered, removed, or obliterated. This includes firearms assembled from parts kits, 3D-printed components, or unfinished frames/receivers (commonly called "80% lowers").

Section 121C: Serialization Requirements

Section 121C requires that all firearms possess a valid, legible serial number. Key provisions include:

• No person shall possess, sell, transfer, or manufacture a firearm that does not bear a serial number
• Persons who currently possess unserialized firearms must apply to have them serialized through an approved process
• It is unlawful to alter, remove, or obliterate the serial number on any firearm
• Frames and receivers, whether completed or unfinished beyond a certain threshold, are subject to serialization requirements

Section 121D: 3D Printers and CNC Machines

Section 121D regulates the use of additive manufacturing (3D printing) and computer numerical control (CNC) equipment to produce firearm components:

• Persons who use 3D printers or CNC machines to manufacture firearm frames, receivers, or other regulated components must register with the state
• Manufacturing a firearm component using these methods without proper licensing is prohibited
• Distribution of digital files specifically designed to produce firearm components may be regulated

Compliance for Existing Unserialized Firearms

Owners of previously lawful unserialized firearms (such as antique firearms or home-built firearms that predated these regulations) should consult current EOPSS guidance on the serialization process and compliance deadlines.

Penalties

Section 121C itself does not contain penalty provisions. Criminal penalties for untraceable firearm violations are found in MGL Chapter 269, Section 11C, which provides imprisonment of not less than 12 months and not more than 2.5 years for knowingly manufacturing, assembling, importing, selling, transferring, purchasing, or receiving an untraceable firearm. There is no fine-only option. Possession of an untraceable firearm is prima facie evidence of guilt under Section 11C, rebuttable by showing lack of knowledge. Additional charges may be brought under Chapter 269, Section 10 for unlawful possession.

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

See also: Building a Firearm from a Lower Receiver in Massachusetts