Developments in the manufacture of homemade, unserialized firearms and lack of enforcement of existing laws threaten to undermine the integrity of the Gun Control Act of 1968 (GCA), the foundation of federal firearms regulation. Enforcement of the GCA is imperative to prevent the uncontrolled proliferation of the increasingly lethal firearms produced by today’s gun industry.

The proliferation of ghost guns and other homemade firearms threatens to destroy the very fabric of federal gun laws. Gaps in federal law have helped create a huge demand for parts used to build homemade firearms, including those commonly known as ghost guns. Under federal law, individuals are not prohibited from manufacturing a gun for personal use. However, unlike guns produced by licensed manufacturers, such weapons are not required to be stamped with a serial number. As a result, they undercut background check and recordkeeping requirements and cannot be traced by law enforcement. To facilitate the construction of homemade firearms, kits that include all of the parts of a fully operable firearm minus the firearm “receiver” or “frame” can be purchased through numerous retail sources, including over the Internet and at gun shows. Receivers house the parts critical to a firearm’s functioning and are defined by federal regulation as “that part of a firearm which provides housing for the hammer, bolt or breechblock, and firing mechanism, and which is usually threaded at its forward portion to receive the barrel,”¹ a definition that does not apply to many modern firearms.

Because receivers are treated as “firearms” under federal law, they are subject to background checks and other restrictions that apply to complete guns. However, ATF has unfortunately taken the position that some receivers, receiver flats, and receiver castings that require only a modest amount of machining to be made into complete firearms are not finished receivers and do not meet the definition of a firearm. This interpretation, combined with the antiquated definition of “firearm frame or receiver,” has created a whole new industry that manufactures what are now commonly known as unfinished or “80 percent” receivers.

To circumvent marking requirements that facilitate tracing as well as background check requirements, criminals are purchasing these unfinished receivers which, with minor additional machining, can be turned into finished receivers and eventually untraceable firearms.

Law enforcement officials have reported an alarming and dangerous proliferation of ghost guns — primarily AK- and AR-type assault rifles and large-capacity semi-automatic pistols — in the hands of criminals, including organized criminal organizations. It is in no way an overstatement that ghost guns threaten to undermine basic firearms regulation at the local, state, and federal levels. Examples include the following.

• District of Columbia police recovered 115 ghost guns in 2019, up from 25 in 2018 and three in 2017.²

• In California, ATF reports that 30 percent of all guns recovered from crime scenes are without serial numbers and are therefore untraceable.³

• In 2016, the New York Attorney General sentenced a defendant on charges that he fabricated and sold untraceable “ghost guns” in Nassau and Suffolk Counties. The office’s undercover “Operation Ghostbusters” revealed that the defendant had ordered unfinished gun parts from different manufacturers across the country and assembled them into 11 fully functional ghost guns, which he then sold to undercover investigators posing as gun trafficking gang members.⁴

• A 2016 GAO report indicates that Mexican criminal organizations are trafficking unfinished receivers and firearm parts, further complicating authorities’ efforts to prevent the illegal smuggling of firearms from the U.S. to Mexico and Latin America.⁵

In addition, advancements in 3D-printing technology offer another avenue for the manufacture of untraceable homemade guns. While 3D printing a functional firearm is possible and raises issues of the degree to which such weapons can evade standard detection technology at airports and other secure environments, the more immediate concern is the ease with which 3D printers can be used to produce key firearm components—such as receivers. There are many examples⁶ of 3D-printed guns being used to circumvent gun laws:

• In 2016 at the Lukeville, Arizona border crossing, U.S. Customs and Border Protection seized an AR-type rifle with a lower receiver that was produced on a 3D printer and modified to fire in fully automatic mode (see photo below).⁷

• In 2016, Eric McGinnis attempted to purchase a semi-automatic rifle but was rejected when the background check identified a protective order filed by his girlfriend. McGinnis then obtained gun parts including a barrel and upper receiver and used a 3D printer to make a lower receiver. From the parts he built a short-barreled AR-15 type rifle (see photo below). He was arrested when police heard him firing the gun in a public wooded area. Police found a “hit list” in his backpack that included home and office addresses of Democratic and Republican lawmakers.⁸

• In 2015, two Oregon residents with felony records were charged with illegally possessing firearms, including an AR-15 assault rifle that incorporated a 3D-printed lower receiver. The rifle also lacked a serial number.⁹

Recommendation: The proliferation of ghost guns and other homemade firearms that evade existing regulations is nothing short of a national emergency. The current regulatory definition of frame or receiver does not adequately capture many modern firearms, including AR-15 assault rifles. Therefore, ATF should immediately initiate a rulemaking to define “firearm frame or receiver” in a manner that is consistent with modern firearm design and available technology and that makes clear that the definition applies to the necessary building block of a firearm that houses the firing mechanism. ATF must also update its interpretation of what constitutes a finished receiver to apply to flats and castings that can readily be machined to function as a receiver. In addition, ATF must send a strong signal to the companies currently producing and marketing ghost-gun components that the agency intends to end the manufacture of ghost guns. ATF should also closely monitor advances in 3D-printed firearms and collaborate with law enforcement to identify the illegal manufacture, sale, and use of 3D-printed guns, including receivers and parts. Such information can then be used to aid in the crafting of approaches to restrict firearm-related 3D-printing activities to those that are legal.

UPDATE: On May 7, 2021, ATF issued a proposed rule, Definition of “Frame or Receiver” and Identification of Firearms, to provide new definitions of “firearm frame or receiver” and amend the definition of “firearm” to clarify when a firearm parts kit is considered a “firearm.” This proposed rule will help stem the proliferation of “ghost guns.” The VPC submitted comments in support of the proposed rule. On April 11, 2022 the Department of Justice issued a final rule to rein in the proliferation of ghost guns. On August 8, 2023, the Supreme Court temporarily reinstated the Biden administration’s ghost gun rule while a challenge to the regulation continues in a federal appeals court. In June, a federal judge in Texas barred ATF from enforcing the rule anywhere in the United States.