Massachusetts enacted ghost gun reform legislation in 2024 to address the proliferation of untraceable crime guns and ensure that individuals prohibited by state or federal law from purchasing firearms cannot skirt the law by purchasing gun kits or parts.¹ The legislation adopted a multi-part approach to comprehensively address the issue.

First, this new law expanded the definition of “firearm” to apply to unfinished firearm frames and receivers that have “reached a stage in manufacture when [they] may readily be completed or assembled to function as a frame or receiver [or are] marketed or sold to the public to become or to be used as the frame or receiver of a functional firearm once completed or assembled.”² This means that Massachusetts’s gun safety laws, such as background checks and gun dealer licensing requirements, apply to these parts in the same way they do to completed firearms. For more information on unfinished frames and receivers, see GIFFORDS’ Ghost Guns page.

The new law also included multiple provisions to stop the unregulated sale and proliferation of unserialized firearms. Subject to narrow exceptions,³ this law now makes it generally unlawful to possess, manufacture, sell or otherwise transfer or import an unserialized firearm, including completed and unfinished frames or receivers.⁴ 

Anyone who manufactures or assembles a privately made firearm must:

• obtain a unique serial number from the department of criminal justice information services;
• serialize the firearm with the obtained serial number; and 
• register the firearm with the department of criminal justice information services

within 7 days of the firearm’s manufacture or assembly.⁵ No person may manufacture or assemble a privately made firearm that does not comply with all state and federal safety regulations.⁶

The law requires the department of criminal justice information services to “develop and maintain a serial number request system to electronically receive, record and process requests for a unique serial number” integrated with the department’s electronic firearms registration system.⁷ The department must establish the request system not later than July 25, 2025, and all firearms must be serialized in accordance with the new law not later than one year after the system is completed and publicly available.⁸

Under Massachusetts Law, no person may “knowingly possess, own, sell, offer for sale, transfer, manufacture, assemble, repair or import” a covert or undetectable firearm.⁹ A “covert firearm” is a firearm either “placed in a camouflaging firearm container [or] constructed in a shape that does not resemble a firearm or is not immediately recognizable as a firearm.”¹⁰ An “undetectable firearm” is one that is either (i) not detectable by metal detectors or “(ii) a major component of a firearm…that, when inspected by detection devices commonly used at secure public buildings and transit stations, does not generate an image that accurately depicts the shape of the component.”¹¹ 

Additionally, Massachusetts ghost gun law regulates 3D printers and computer numerical control (CNC) milling machines which can be used to privately manufacture firearms. As of October 23, 2024, only those who possess a valid license to carry firearms may use a 3D printer or CNC milling machine to manufacture or assemble a firearm.¹² 

Furthermore, it is illegal to sell, offer to sell or transfer a 3D printer or CNC milling machine “that has the primary or intended function of manufacturing or assembling firearms” to anyone in Massachusetts.¹³ 

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1. See 2024 MA HB 4885.[↩]
2. Mass. Gen. Laws ch. 140, § 121.[↩]
3. SeeMass. Gen. Laws ch. 140 § 121C(b) & (g) for exceptions to the ghost gun law’s requirements.[↩]
4. Mass. Gen. Laws ch. 140 § 121C(b).[↩]
5. Mass. Gen. Laws ch. 140§ 121C(c).[↩]
6. Mass. Gen. Laws ch. 140 § 121C(d).[↩]
7. Mass. Gen. Laws ch. 140 § 121C(e).[↩]
8. 2024 Mass. Ch. 135 § 158.[↩]
9. Mass. Gen. Laws ch. 140 § 131N.[↩]
10. Mass. Gen. Laws ch. 140 § 121.[↩]
11. Id.[↩]
12. Mass. Gen. Laws ch. 140 § 121D(a).[↩]
13. Mass. Gen. Laws ch. 140 § 121D(b).[↩]