By Alaina De Biasi, Anthony A. Braga, Brad Velasquez & Garen Wintemute 

Background: Privately made firearms (PMFs) or “ghost guns” are homemade, unserialized, untraceable firearms that have been increasingly used in violent crime in the United States. Very little is known about the types of PMFs recovered by law enforcement agencies and the crimes associated with these recoveries. This lack of information limits effective violence prevention policies and practices. Comparative analysis of PMF recoveries in specific cities helps clarify whether local PMF patterns and characteristics vary or reflect more general trends. This research advances epidemiological understanding of emergent violent gun injury prevention challenges by identifying variations in recovered PMF types and use in violent, drug, and weapon-related offenses in Los Angeles and San Diego, California.

Methods: Conjunctive analysis of case configurations (CACC) identifies patterns among observations (i.e., case configurations) and calculates their probability associated with a given outcome. CACC was used to identify the most common types of PMFs recovered by the Los Angeles (LAPD) and San Diego (SDPD) police departments. For each department and offense type, case configurations with above-average probabilities of offense involvement were determined. Comparisons across departments were made to identify similarities and differences in PMF characteristics and usage.

Results: PMFs were more likely to be involved in violent and weapon-related offenses in Los Angles but more likely to be involved in drug-related offenses in San Diego. In both cities, the 9 mm Polymer 80 handgun was the dominant PMF. However, 9 mm handguns were most likely to be involved in weapon-related offenses in Los Angeles compared to 0.40 handguns in San Diego. Furthermore, large-caliber handguns tended to display above-average probabilities of involvement in violent and drug offenses in Los Angeles. Long guns were represented in case configurations with above-average probabilities of involvement in substantive crimes, including violence.

Conclusions: Comparative analyses of PMF recovery patterns in Los Angeles and San Diego reveal meaningful contextual variations in PMF characteristics and suggest intentional firearm type selections by offenders. The results support increased regulation of PMFs and highlight the importance of efforts to identify and disrupt the illicit supply of large-caliber PMF handguns and PMF long guns.

Injury Epidemiology volume 11, Article number: 17 (2024)

By Garen J. Wintemute

Off-the-books, untraceable “ghost guns” can now be manufactured at home, easily, and in large numbers; they contribute ever more frequently to firearm violence, including hate violence and domestic terrorism. The Bureau of Alcohol, Tobacco, Firearms and Explosives estimates that in 2019 alone, law enforcement agencies recovered more than 10,000 ghost guns. The manuscript describes the current situation and suggests specific actions that state and federal governments can take to avert disaster.

Injury Epidemiology volume 8, Article number: 13 (2021)

By Everytown for Gun Safety

In California, a 16-year-old boy shot and killed two of his classmates and shot and wounded three others with a handgun. In Washington D.C., ghost guns were used in four recent fatal shootings. In Arizona, a neo-Nazi sex offender bragged on Facebook about his arsenal of firearms and homemade assault-style rifles. All of these people were legally prohibited from buying guns. But due to a dangerous wrong turn by ATF these individuals were able to access a haunting new source of firepower: ghost guns. Ghost guns are the thread connecting a horrific series of recent shootings. These do-it-yourself (DIY) firearms are made from parts available without a background check and are predictably emerging as a weapon of choice for violent criminals, gun traffickers, dangerous extremists, and, generally, people legally prohibited from buying firearms. Because it has no serial number, a ghost gun cannot be traced back to where it came from, which frustrates police investigations and robs victims and survivors of justice. The rise of ghost guns is the fastest-growing gun safety problem facing our country. But disturbingly little is known about who sells ghost guns, who buys them, and how much they are used in crime. The scant data available is disjointed and barely scratches the surface of the issue. To remedy this problem, Everytown for Gun Safety examined available data, including a sample of 80 online ghost gun part sellers and more than 100 federal prosecutions involving ghost guns, to find out who is selling and using these deadly weapons and what can be done about it.

New York: Everytown for Gun Safety, 2020. 28p.

By Nicholas Simons, Jaclyn Schildkraut and Julianna Caruso. Regional Gun Violence Research Consortium

On April 11, 2022, the Biden administration announced the submission of new rules issued by the United States Department of Justice (DOJ), more specifically the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF), addressing the proliferation of ghost guns across the nation….

What exactly are ghost guns, and what challenges do they pose? Moreover, what do these new rules do to contribute to a solution to such challenges? Privately made firearms (PMFs), which have become informally known as “ghost guns” due to their virtually untraceable nature, function similar to firearms wholly constructed by licensed firearm manufacturers but have a fraction of the regulations. In 2021, law enforcement in New York State recovered 637 PMFs (135 percent more than the year prior), reflecting continued annual increases from 44 in 2018 (the first year of reporting), 100 in 2019 (up 117 percent over the year prior), and 2020 (an increase of 171 percent). Other law enforcement agencies across the country, particularly those located in larger cities, have reported similar jumps in recoveries: Law enforcement in Boston has seen a nearly three-fold increase in the city since 2019; Philadelphia reported a five-fold increase since that year. Data from the ATF mirrors these trends: the recorded number of suspected PMF recoveries nationally increased more than 90 percent between 2020 and 2021 and more than ten-fold between 2016 and 2021. Such increases, however, must be interpreted with caution as they may be an artifact of increased reporting by jurisdictions.

While these increases represent a relatively low percentage of total gun recoveries, they illustrate that ghost guns pose a unique and rapidly growing challenge. Law enforcement agencies are unable to trace the origins of ghost guns used in crime and ultimately curb their flow at the source. While the federal government has taken first steps to regulate these weapons, state and local lawmakers have for several years been exploring and enacting policies designed to monitor and prevent ghost guns from falling into the hands of individuals who are prohibited from purchasing or possessing firearms.

Albany, NY: Rockefeller Institute of Government, 2022. 20p.