Thinking Seriously About Gun Control: 10-Round Magazine Limits Are A Bad Idea

Polls reveal most Americans favor laws limiting the capacity of firearms magazines to 10 rounds, and the New York Times reports that several generally pro-gun federal legislators have expressed support for such legislation. Surely, they argue, no one needs more than 10 shots to kill a deer or stop an armed intruder. Other than in war, their main purpose, clearly, is to murder large numbers of innocent citizens. So, they should obviously be outlawed. So goes the mantra, but it is far from the truth.

In reality, such bans would have a minimal, if any, impact on criminal homicides, but they might well endanger the lives of law-abiding citizens and, in the process, might incentivize criminals to shift to far more lethal weapons that could eventually cost far more lives. And, in the process, they might make us accustomed to trashing our Bill of Rights.

Only in Hollywood do people shot with a 9mm bullet immediately fall to the ground dead. People have been hit more than 20 times with such bullets and survived the experience. While homeowners generally do not wish to kill an intruder—or intruders, as home invasions and other violent crimes are often committed by multiple armed assailants—or anyone else, to be successful, they must act quickly to do whatever is necessary to end the threat. And doing that often requires multiple hits.

There is also a serious risk of repeatedly missing the target under the stress of a gunfight. A study of New York Police Department shootings between 1998 and 2006 revealed that trained police officers hit their targets under the stress of a gunfight 18% of the time. On average, that’s just under two hits with a 10-round magazine. And that includes superficial wounds that have little chance of incapacitating the criminal.

Image: Keanu Reeves trains to be John Wick. YouTube screen grab.

A similar study of 149 officer-involved shootings by the Dallas Police Department between 2003 and 2017 concluded that officers fired an average of 2.4 rounds in a typical gunfight and struck the suspect at least once 54% of the time. Half of the officers did not score a single hit when firing their handguns under such stress. A 2022 study reported in the International Journal of Environmental Research and Public Health cited these and other data while noting that “high anxiety,” like being involved in a gunfight, is “a trait known to negatively impact on marksmanship.” 

Yet another study did the math, concluding that it takes 2.45 hits with a 9mm pistol on average to end a threat and 5.55 shots to make a hit. That adds up to 13.6 rounds fired on average to incapacitate an attacker, and that's for just one attacker—which is hardly good news if you are trying to defend your family while limited to a 10-round magazine.  (It is true that homeowners can carry more than one magazine, but when awakened in the middle of the night by an uncertain noise while wearing pajamas, the likelihood they would think to do so is slim. They may well want their second hand free for opening doors or carrying a flashlight.)

It should be axiomatic that most homeowners have far less firearms training than professional police officers, so their accuracy under stress will likely be even less than the New York Police officers’ 18% hit rate. Limit them to a 10-round magazine, and perhaps they will hit a single intruder once or twice, which is less than the 2.5 hits that a study of more than 450 shootings with 9mm pistols over a ten-year period concluded were necessary to incapacitate the average threat. Add multiple criminals to the mix, and their victims will have little chance.

The flip side of self-defense is to look at those who commit gun crimes. The assumption that those who are determined to commit serious felonies will obey a new law limiting magazine size is about as logical as assuming posting a “No Guns Zone” sign will do anything beyond disarming honest citizens who might otherwise be able to intervene and, perhaps, stop a shooting.

Some ban advocates seem to think that a shooter must reload an empty magazine one round at a time before he can reengage. But criminals can carry multiple loaded magazines, which can easily be swapped in two or three seconds—about one second with serious practice.

Consider for a moment the worst mass school shooting in American history, which occurred at Virginia Tech in 2007. One of the two firearms used was a .22 caliber pistol fed by 10-round magazines. The other was a 9mm Glock 19, for which the shooter had purchased several 10-round magazines on eBay and additional 15-round magazines at local gun stores.

Over nine minutes, the killer fired more than 170 rounds while murdering 30 people and wounding another 17. That comes out to about 3.6 rounds per victim and a little more than 11 seconds between shots. Most of the magazines he used reportedly held 10 rounds, and the after-action reports indicate that all the loaded magazines still in his possession when he committed suicide were of the high-capacity variety.

No wonder that multiple scientific studies have concluded that banning high-capacity magazines has little to no effect on crime. A 2019 study by experts from the Boston University School of Public Health concluded: “We did not find any significant association between homicide rates…[and] large capacity ammunition magazine bans….” The prestigious Rand Corporation’s recent review of five studies evaluating the effects of the 1994 federal ban on high-capacity magazines concluded: “[W]e find inconclusive evidence for the effect of high-capacity magazine bans on firearm homicides.”

George Mason University Professor Christopher Koper, who conducted multiple studies for the Department of Justice, noted the studies disclosed “very, very little evidence,” that the 1994 ban on assault weapons and large capacity magazines reduced gun violence. “[W]e concluded that the ban had not had a discernible impact on gun crime during the [10] years it was in effect.”

Space precludes seriously addressing the Second Amendment aspects of this issue here, but they are considerable. And it makes zero sense to narrow the scope of our Bill of Rights without clear evidence of some major benefit in so doing.

In the 2008 DC v. Heller case, the Supreme Court gave maximum Second Amendment protection to firearms “typically possessed by law-abiding citizens for lawful purposes….” According to Shooting Illustrated, the most popular full-size 9mm pistols sold in America by each of the six largest gunmakers come standard with at least 15-round magazines, and the average capacity is slightly more than 17.

A 1995 report by the DoJ Bureau of Justice Statistics reported that extensive interviews with imprisoned felons convicted of gun crimes disclosed: “the criminals preferred larger caliber guns” than favored by the general public. And a 2018 study reported by the  Journal of the American Medical Association (JAMA) found that shootings with larger caliber firearms produced more lethal results. 

Although it is extremely uncommon for anyone to fire ten shots in a gunfight, criminals are drawn to 9mm handguns in part because their magazines can hold more ammunition. Assuming that a magazine capacity ban would have any effect on the behavior of criminals, one result might well be to shift to higher caliber pistols. And a shift from 9mm to 10mm would roughly double the muzzle energy. The 10mm Glock 20 is the most popular pistol sold in Alaskan bear country, and is issued to Artic patrol members in Greenland—where it has “proven effective against charging polar bears.” (The average adult male polar bear weighs three to six times more than the average adult male human being.) A study of more than 1,000 shootings that occurred in Boston between 2010 and 2014 noted that the victims on average “died in 1 of 6 cases.” But for shootings involving 10mm handguns, the fatality rate was 100%.

The American people are understandably frustrated over school shootings and other criminal misconduct involving firearms. And there are a number of measures involving such things as mental health treatment, enhancing punishment for using firearms in crimes, and other steps that might actually help. But denying law-abiding citizens the tools they need to protect themselves and their families is not the answer, and, in addition to gratuitously endangering honest American lives, restrictions on magazine capacities might well incentivize criminals to shift to far more lethal weapons.

A Vietnam veteran, Professor Turner retired in 2020 after more than three decades of teaching at the University of Virginia School of Law. An NRA-certified rifle and pistol instructor for more than six decades, he shot competitively as a member of military rifle and pistol teams.

If you experience technical problems, please write to