States that ban large-capacity magazines (LCMs)—detachable ammunition feeding devices that hold more than 10 bullets—experience substantially fewer high-fatality mass shootings than states that do not ban LCMs, according to a new study led by researchers at Teachers College and the Harvard T.H. Chan School of Public Health.
The study finds that high-fatality mass shootings—defined as six or more fatal victims, not including the perpetrators—occurred in states that do not restrict ownership and possession of LCMs at a rate that was more than double the rate for states that do restrict LCMs. In addition, deaths in high-fatality mass shootings, relative to the population, were more than three times higher in states that did not restrict LCMs.
LCM bans seek to lower the frequency and lethality of mass shootings. The study finds that LCM bans appear to be saving lives. The rationale behind LCM bans is that, if gunmen are forced interrupt their attacks more frequently in order to reload due to lower ammunition capacity, those precious seconds can allow potential victims in the line of fire to run, hide, or fight back—three widely prescribed life-saving tactics for surviving an active shooting.
“Think back to the 2011 rampage in Tucson that targeted the crowd at a political meet-and-greet hosted by former Arizona Congresswoman Gabrielle Giffords,” said TC research professor Louis Klarevas, lead author of the study. “The gunman in that attack used a handgun armed with a 33-round magazine to kill six and wound another 13, including Rep. Giffords. The casualty toll would certainly have been higher had the gunman not been tackled while switching out one large-capacity magazine for another. But by the same reasoning, the casualty toll would have been lower had the gunman been tackled after emptying a much smaller 10-round magazine. Imagine how many victims would have been spared if the gunman had fired 23 fewer bullets that day.”
In the last five years, high-fatality mass shootings have been occurring at a rate of more than four incidents per year. Approximately half of these attacks, prominent among them the massacres in Orlando, Las Vegas, and Sutherland Springs, claimed 10 or more lives. When perpetrators of high-fatality mass shootings used LCMs, their attacks resulted in a 62-percent higher average death toll.
The study analyzed the time period from 1990-2017. The researchers selected 1990 as the starting point because, that year, New Jersey became the first state to restrict LCMs. Since then, eight other states plus the District of Columbia have enacted bans on LCMs. From September 1994 until September 2004, the possession or sale of new LCMs was prohibited nationwide by the federal assault weapons ban. That law expired in 2004, after Congress opted not to renew it.
The study finds that the 1994 federal ban appears to have been effective in reducing mass shooting violence. Yet, even without a nationwide ban in place, states that tightly restricted LCMs still experienced high-fatality mass shootings at a lower rate than states that did not restrict LCMs.
It seems that when LCMs are legal and available, they are more likely to be acquired and used by mass murderers. Nevertheless, since some potential shooters may import LCMs into states where they are prohibited, restricting LCMs across all 50 states promises a more effective way to reduce deaths associated with mass shootings.
“Whether or not to ban large-capacity magazines is at the heart of the national debate over how to reduce gun violence,” Klarevas added. “Our research suggests that imposing tight restrictions on LCMs offers a practical legislative solution for helping to safeguard Americans from the threat of mass shootings.”
The study, “The Effect of Large-Capacity Magazine Bans on High-Fatality Mass Shootings, 1990-2017,” will appear in the December 2019 issue of the American Journal of Public Health, and published online on October 17, 2019. Andrew Conner, a medical student at the Frank H. Netter, MD, School of Medicine, Quinnipiac University, was a co-author.