Ghost guns have no serial numbers. They are untraceable because their owners assemble them piece by piece, either by purchasing gun parts or — as may have been the case in the murder of UnitedHealthcare CEO Brian Thompson — by producing them wholly or in part with a 3D printer. Either way, the owner avoids background checks.

The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives refers to ghost guns as privately made firearms — or PMFs — and defines them as “firearms (including a frame or receiver) that have been completed, assembled or otherwise produced by a person other than a licensed manufacturer. PMFs are also made without a serial number placed by a licensed manufacturer at the time the firearm was produced. However, not all PMFs are illegal, and not all firearms are required to have a serial number.”

Ghost guns can take many forms. Here are some of them, from rifles to pistols:

(Courtesy: ATF.gov)

Journalists have many angles through which to explore ghost gun regulations, their real threat and how the issue is playing out politically and in the U.S. Supreme Court.

Ghost guns’ use in crime

Ghost guns are “emerging as the weapon of choice for criminal activity,” according to the Brady Campaign to Prevent Gun Violence. Everytown For Gun Safety says, “Ghost guns are the fastest-growing gun safety problem facing our country.”

Everytown has been collecting reports of ghost guns being used in crimes for more than a decade. Here are some of the 2024 incidents:

(Courtesy: Everytown for Gun Safety)

Gun control advocates sometimes use statistics that stress how many ghost guns are recovered by police. When you see the increase in these untraceable weapons expressed as a percentage, it can appear that they are more widely available than they really are.

The truth is that while police are recovering more untraceable guns, they are still a tiny minority of all guns used in crimes.

Data from Everytown reveals the actual number of ghost guns recovered in various cities and states. The numbers do seem to be growing. New data will be forthcoming from agencies as they close the books on 2024’s crime data.

(Courtesy: Everytown for Gun Safety)

According to the ATF, law enforcement officers found 20,000 suspected ghost guns — again, labeled as PMFs or privately manufactured firearms — in 2022. That is 10 times more than they found in 2016.

(Courtesy: U.S. Department of Justice)

It is a big increase, but ghost guns still account for only .01% of guns that the ATF tried to trace between 2017 and 2021.

Gun owners sometimes grind off serial numbers, just as car thieves may try to erase VIN registrations from autos. The ATF reports that of the 45,240 firearms without serial numbers that were recovered from crime scenes and submitted for tracing from 2016 through 2021, it successfully traced 445, or fewer than 1%.

Federal ghost gun regulations

The Biden administration issued a rule in August 2022 requiring all gun kits and other key gun parts to include serial numbers, to only be sold by licensed gun dealers and for buyers to to be subject to a federally required background check.

The rule, enacted by the ATF, relies on the authority contained in the Gun Control Act and addresses what the administration calls an “exponential” increase in ghost guns.

Some cities say they have seen a flattening or decline in ghost gun recoveries since the federal rule was enacted.

The rule does not outlaw weapon parts kits but imposes the same licensing, recordkeeping and background checks that gun dealers keep when they sell fully assembled firearms. The federal law regulates the two main parts of a gun, the frame and the receiver, which operate the firing mechanism. Before the Biden administration regulation, if the frame or receiver was “unfinished,” it did not have to have a serial number.

As you can read in a recent Supreme Court transcript, unfinished receivers only need holes drilled to be operational.

Even with the 2022 ruling, there are loopholes in the law, as the ATF notes:

Individuals who make their own firearms may use a 3D printing process or any other process, as long as the firearm is “detectable” as defined in the Gun Control Act. You do not have to add a serial number or register the PMF if you are not engaged in the business of making firearms for livelihood or profit.

An increasing number of states are imposing their own regulations on homemade weapons.

There are a number of 80% assembled receiver/frame kits available online. They come complete with drill bits and jigs that show the buyer where to drill

(Screenshot/UsPatriotarmory.com)

The Biden administration called such kits “buy build shoot” kits and described them as kits “that individuals can buy online or at a store without a background check and can readily assemble into a working firearm in as little as 30 minutes with equipment they have at home.”

There are also websites that give detailed instructions on how to build a homemade ghost gun.

Wired reported that the gun that was used in the UnitedHealthcare killing “appears to be a Chairmanwon V1, a tweak of a popular partially 3D-printed Glock-style design known as the FMDA 19.2 — an acronym that stands for the libertarian slogan ‘Free Men Don’t Ask.’”

The constitutionality of ghost guns

The U.S. Supreme Court’s first case of the current term focused squarely on whether the Biden administration’s ghost gun regulations are constitutional.

While it is difficult to predict how the justices will rule, the majority of their questions and comments indicated that they agreed that the ghost gun regulations were constitutional. U.S. Solicitor General Elizabeth Prelogar told the court there has been an “explosion in crimes committed with ghost guns.”

The Biden administration also launched the “National Ghost Gun Enforcement Initiative,” which trained prosecutors on how to bring cases against people who use untraceable guns in crimes.

State-by-state ghost gun laws

Some states have enacted their own ghost gun rules. Even if the Supreme Court overturned the federal regulations on ghost gun parts, 15 states have enacted regulations that would still stand.

(Data: Everytown Research and Policy/Graphic: Statista)

The patchwork status of state regulations makes it possible to shop across borders to avoid those regulations, including those that raised the age limit for buying semi-automatic weapons and those that required background checks to purchase ammo.

Gun rights groups are launching state-by-state challenges to ghost gun laws, such as in Colorado, where a ghost gun ban went into effect this year. “Home-building firearms has been something that’s been done in our country since the beginning of time,” said Rocky Mountain Gun Owners executive director Ian Escalante.

Ghost guns and 3D blueprints

In his last term, Donald Trump attempted to allow the release digital files that would allow anyone to download 3D printer plans for gun parts from the internet. Attorneys general in 20 states went to court to block the release of those files.

The first known 3D-printed pistol came from an Austin, Texas-based company eleven years ago. The company distributed the digital files for the pistol online but, after 100,000 downloads, the State Department intervened.

Why did the State Department get involved in a gun issue? The government argued that distributing the data files was analogous to shipping weapons internationally. Eventually, the Texas-based company was allowed to continue sharing the files as a form of protected free speech. But then the states sued to stop it.

Last year, U.S. Sen. Kirsten Gillibrand of New York introduced the 3D Printed Gun Safety Act, which would stop the distribution of 3D blueprints for firearms. A similar bill filed in 2021 went nowhere in the Senate.

New York lawmakers considered a bill that would regulate 3D printers, not just the guns they could produce. One bill would require anybody who bought a 3D printer capable of producing a 3D gun to undergo a background check. That bill also went nowhere.

Ghost gun printing technology is advancing

In the meantime, 3D gun technology is advancing. Various websites show the ways that enthusiasts are using 3D printing to build guns, suppressors, magazines and other attachments. These are some of the most popular ghost gun plans online.

Some states have specifically mentioned 3D-printed guns in their ghost gun regulations.

3DPrint.com, which covers the 3D printing world, reports:

California, New Jersey, Massachusetts, and Rhode Island have taken some of the strictest stances against 3D printed firearms. In California, laws mandate obtaining a unique serial number for any manufactured or assembled firearm and prohibit any firearm undetectable by metal detectors, including 3D printed guns.

New Jersey’s approach is similarly robust, focusing on materials by outlawing the creation, distribution, or possession of firearms predominantly made from plastic—directly targeting 3D printed guns. Massachusetts also prohibits the manufacturing, distributing, possessing, or selling any firearm or ammunition undetectable by metal detectors or X-ray machines. At the same time, Rhode Island has enacted laws requiring serial numbers and background checks for parts, effectively banning the 3D printing of guns.

Ghost guns and future regulation

The Firearm Industry Trade Association wants the next Trump administration to disband the White House Office of Gun Violence Prevention and replace it with an office to support he Second Amendment.  The association argues that ghost guns are a “gun control boogeyman” and says:

Americans have always had the ability to legally make firearms on their own and some choose to do so as a hobby. It has not created a wave of “ghost guns.” It has allowed individuals who are passionate about building their own firearms to assemble them in their homes. This is the exception, not the rule. The overwhelming majority of firearms are bought through commercial sales, produced by manufacturers and sold by retailers that are federally licensed and regulated.

It is already illegal under the federal Undetectable Firearms Act to manufacture, import, sell, ship, deliver, possess, transfer, or receive an undetectable firearm. Even firearms produced with 3D printing technology are required to include a component made of metal, and hence detectable by metal detectors and x-ray machines. In addition, ammunition cartridges are made with metal components that are detectable. Of course, even without metal components, current Transportation Security Agency (TSA) screening machines will detect an object, regardless of its composition.

Ghost gun reliability

Are 3D-printed guns reliable? It all depends on the quality of the manufacturer. As this really interesting story from VICE found, printing a 3D gun out of plastic does not usually produce a reliable weapon — and the printing is just the beginning of the process. Vice attended a “celebration” for ghost gun makers in Florida who competed against each other. Every gun was either printed or made from kits they bought online.