In the next several weeks we will see new gun legislation proposed in both the House of Representatives (sponsored by Rep. Diana DeGette and others) and the Senate (sponsored by Sen. Dianne Feinstein and others). Both bills will call for restrictions on the sale of high capacity magazines.

For the thousands of Americans who die each year by gun suicide and gun accidents, these bills will have little effect—one bullet is enough to kill. There is ample evidence, however, to suggest that an effective ban on high-capacity magazines will reduce the number of deaths in gun homicides, especially in mass shooting scenarios.

This graph reveals the correlation between magazine capacity and number of casualties during mass shootings in recent history.

This graph reveals the correlation between magazine capacity and number of casualties during mass shootings in recent history.

A seven-year-long study of gunshot victims observed an increasing incidence of gunshot victims who had been shot multiple times. The proportion of gunshot victims with two or more gunshot wounds grew from 26% in the early 80s to 43% by 1990[1]. Over the same span of years, semiautomatic handguns like the Beretta 92 and Glock 17 were replacing the .38 and .357 caliber revolvers that had been the most popular handguns in the United States in the preceding decade. The ammunition capacity in a fully-loaded handgun rose from typically six rounds to typically 15 rounds, and shooters exploited that advantage, shooting their victims multiple times and increasing the likelihood of fatal injury.

Parents Against Gun Violence researchers have identified 37 mass shooting incidents (excluding robberies and armed confrontations) involving more than 6 victims in the United States since 1945. In 35 of 37, the perpetrators carried semiautomatic weapons. In 33 of 37, the perpetrators carried magazines with a capacity greater than 10 rounds. In the recent mass shootings in Tucson, Aurora, and Newtown, the perpetrators sought out inordinately large magazines, including the 100-round drum magazine James Holmes used to shoot 70 people in a movie theater. These mass murderers clearly believe that a higher-capacity magazine will equate to more fatalities.

Opponents of the high-capacity magazine ban will point out that smaller capacity magazines can be rapidly exchanged, and will argue that such a ban will not slow or hinder a mass shooter. Online videos show expert shooters removing an empty magazine and replacing it with a fully loaded magazine with dazzling speed. Let’s remember, though, that these videos are impressive precisely because the reloading skills depicted are remarkably rare—it takes years of practice to achieve such proficiency, and the perpetrators of most mass shootings are young men with limited experience. There are cowboy trick shooters who can operate a single-action revolver or lever-action rifle with astonishing speed—but Annie Oakley doesn’t fit the profile of a mass shooter. We’re not seeking laws to stop Wild Bill; we’re seeking laws to stop Jared Loughner. More »