The same weapons that the gun industry pumps out in ever greater numbers are more likely to fatally injure people, a new study shows. The public safety risks of popular medium- and large-caliber firearms models are compounded by another fresh research finding: Criminals are seeking out those same guns.

In the first study, scholars dug into Boston Police Department investigative files and sorted shootings by the caliber of the guns with which they were committed. Caliber is a measure of a bullet’s diameter, which in turn affects the force with which it strikes a target and the size of the channel as it penetrates. Sure enough, the researchers found that, in Boston, gunshot wounds from medium- to large-caliber rounds were significantly more likely to kill victims than wounds from smaller-caliber bullets. According to the paper by Anthony Braga of Northeastern University and Philip Cook of Duke University, victims were 2.3 times more likely to die when shot with what the authors call medium-caliber handguns like the 9mm or .380 than they were if shot by weapons that fire small bullets like the .22.

The study shows, Cook says, that “the type of weapon matters separately and in addition to the intention of the attacker, skill of the attacker, and the circumstances of the attack, in terms of likelihood that the victim will die.”

Victims shot by what the authors classify as large-caliber handgun rounds, like the .45, were even more likely to die, with Braga and Cook’s analysis showing those wounds were 4.5 times more fatal than those from small-caliber rounds.

“Homicides were more likely to involve large-caliber firearms relative to nonfatal shootings,” the authors wrote. “The implication is that if the medium- and large-caliber guns had been replaced with small caliber (assuming everything else unchanged), the result would have been a 39.5% reduction in gun homicides.”

Not only are larger-caliber handguns deadlier than smaller pistols, they have exploded in popularity among legal gun buyers. Guns like the 9mm have become synonymous with the “good guy with a gun,” civilians who go armed in public for purposes of self-defense.

According the Bureau of Alcohol, Tobacco, Firearms and Explosives, American gun companies produced approximately 2.3 million 9mm semiautomatic handguns in 2016, the most recent year for which manufacturing data is available. That’s more than four times the combined number of all small-caliber semiautomatic pistols manufactured the same year.

Compare that to data from 1990 when gunmakers produced just shy of 350,000 semiautomatic 9mm pistols, slightly fewer than the number of pistols that fired the relatively puny .22 round they made that year.

As we reported in 2016, the gun industry’s shift from producing more small, cheap “Saturday Night Special” pistols so common from the 1960s through the 1980s to more large-caliber, deadlier handguns depended on the expansion of concealed-carry laws.

In 1981, 19 states banned concealed carry in any form. But after decades of lobbying by the National Rifle Association, today all 50 states allow residents to carry in public to one degree or another. As a result, people who in a previous age would never have considered going armed in public now consider concealed carry acceptable. In certain parts of the country, the practice has gone mainstream: In Florida, more than 1.9 million residents — or one out of 10 people — currently have an active concealed weapons license.

To take advantage of the opportunity presented by loosened public carry laws and fear-based demand, gunmakers market weapons that pack the most powerful round into the most concealable gun frame possible. But “good guys with guns” aren’t the only people who hear that pitch.

Another study published this month in Criminology by Braga and David Hureau of the University of Albany examined the dynamics of Boston’s criminal market for guns. The authors interviewed criminals who were keenly aware of the differences between weapons, and who pay a premium for the kinds of newer semiautomatic pistols also favored by concealed carriers.

“All respondents acknowledged that the most desirable guns were larger caliber semiautomatic pistols,” Braga and Hureau wrote.

The most popular caliber among the criminals interviewed was the 9mm. The gang members and drug dealers who spoke with Braga and Hureau told them they preferred these kinds of guns because they fire a powerful cartridge, can store many rounds in a magazine, and are easily concealed in a waistband.

Cook says empirical research like these two papers get to the heart of gun policy.

“There are two fundamental empirical issues in the debate over gun control: does the type of weapon matter to lethality, and does the general availability of guns increase crime?” he said. “If you believe those things matter, then you can make policy to save lives.”