The 5.56 NATO bullet has been used in some of the country’s most horrific public mass shootings — including the ones so deadly that we refer to them by shorthand. Sandy Hook. Parkland. Aurora. Uvalde.
It’s hard to predict when these kinds of tragedies will take place, or the catastrophe’s magnitude. In mass shootings in particular, it can also be hard to anticipate the severity of the wounds victims may suffer. But according to a group of physicians and firearm researchers, there are ways to calculate this type of harm. They’re working to create a common metric to measure the lethality of different guns and bullets — an effort that could help policymakers better decide how to respond to varying levels of harm.
“The framework that ‘a gun is a gun and it doesn’t matter what the gun is’ is just not accurate,” said Dr. Eric Fleegler, a pediatric emergency medicine physician at Massachusetts General Hospital. “The gun is the instrument that shoots the bullet, and it is the bullet that is ultimately the agent that causes the damage to the human body.”
In medicine, experts have long understood a disease’s lethality by a measure known as case fatality rate (CFR), or the proportion of people who die from a specific disease among all the people diagnosed with it over a given period. The case fatality rate for untreated HIV is 90 percent, for example; the rate for rabies is 99 percent, and it’s 30 percent for smallpox. This percentage is key for developing treatments and understanding the severity of specific diseases.
Fleegler and other researchers are working to apply that same methodology to bullets, when paired with specific firearms. In a 2019 study published by Annals of Internal Medicine, researchers found a 90 percent case fatality rate for firearm suicide — meaning that 90 percent of people who attempt suicide with a firearm die — and compared that to intentional overdose attempts, for which the CFR is only 2 to 3 percent.
It is more difficult to parse out the rate of firearm homicides because there are more factors contributing to lethality. Previous research has found that the CFR range for firearm homicide could be up to 25 percent — but also that being shot with a large-caliber bullet increases the likelihood of death four-fold.
But bullets are just a part of the equation. In an article published recently in the Journal of the American Medical Association, Fleegler and his co-authors reckoned with another factor: age. When they looked at the Sandy Hook, Uvalde, and Parkland mass shootings — in which the same kinds of bullets and firearms were used — they found that case fatality rates lowered as victims’ ages increased. The CFR was highest, at 100 percent, among the 20 first-graders who were killed in the Sandy Hook shooting; in the Parkland shooting, in which the victims were 15- and 16-year-olds, the CFR was 50 percent.
That recent study is a snapshot of a larger movement to create an index, known as a wounding ballistics theoretical lethality index, to scientifically illustrate how bullets shot from different firearms perform under specific parameters. The idea goes back decades: Trevor Dupuy, a military historian, developed his own index of military weapons in 1964, and charted how weaponry became more lethal over time.
Dr. Stephen Hargarten, an emergency physician at the Medical College of Wisconsin and a co-author of the JAMA article, is at the forefront of researching wounding ballistics, work that may lead to a lethality index. He’s spent the past five decades working in medicine, and witnessed firsthand the damage bullets can do. In the 1990s, Hargarten was among a group of physicians who spoke out against the Winchester “Black Talon,” a bullet with razor-sharp barbs that resulted in greater injury in patients and tears of surgical gloves, exposing physicians to diseases including hepatitis and AIDS.
Today, Hargarten’s work on the potential index is focused on quantifying the energy range of various ammunition and visualizing the damage that the bullets can cause.
“The technology that we used back in the 1990s… is primitive compared to what we have now. So what is exciting is that we now have a microscope for this disease,” Hargarten told me. “Think about when they are talking about infectious diseases and they finally could see the little critters in the 1870s and 80s and what their shapes were like, ‘Oh, that’s what’s causing the diseases like cholera, or tuberculosis.’”
To gain a scientific understanding of the damage, Hargarten and his research team examined the firing of various bullets from several guns through a ballistic gelatin base that simulates muscle tissue. The first test, a 32 caliber bullet paired with a handgun, passed through the simulated tissue; the next, a 5.56 NATO bullet fired from an AR-15, ripped through the gelatin, demonstrating greater damage to the human body. That 5.56 NATO bullet had a velocity approximately three times that of the first bullet that was fired from the handgun.
“When we think about people being hit by a bullet, most of us envision something we’ve seen in the movies, so it’s very hard to understand what’s actually happening to the human body,” Fleegler told me. “These visuals are here to give a very vivid, although not overly graphic, example of what’s going on.”
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The JAMA article laid out a few different suggestions focused on reducing harm from bullets, including a tax rate comparable to other harmful products like cigarettes, or limiting the number of bullets purchased in one sale and requiring background checks for bullet sales.
“In our work, we talk about bullets as pathogens, and the guns as sort of vectors, similar to a mosquito carrying malaria. … It was important for us to highlight firearm violence in the same way,” said Dr. Laura Vargas, a psychiatry professor at the University of Colorado and a co-author of the article in JAMA. “The policies that we highlight are not anything new either, they have been proposed before.”
Vargas said it’s important to look at the financial, emotional, and communal damage of U.S. gun policy both within our borders and abroad to really grasp the importance of these policy recommendations. This type of communal understanding of firearm violence is also proposed in the article’s solutions, with ideas like licensing requirements for ammunition dealers and further research focused on understanding bullets’ damage on different groups.
“The science informs our ability to understand what’s going on, and then it opens up discussions that hadn’t happened before,” Hargarten said. “Because of that, perhaps more interesting solutions might bubble up that are more focused on what we’re trying to do. We’re trying to reduce firearm-related harm.”
Correction: An earlier version of this story included erroneous credit for research conducted on the case fatality rate for gun suicide compared to intentional overdose attempts. We apologize for the error.
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