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 »

On an episode of Meet the Press that aired Sunday, December 16th, two days after the Newtown shooting, Senator Dianne Feinstein announced that she would bring a new assault weapons ban to the floor in 2013. Feinstein was one of the authors of the 1994 assault weapons ban, which expired in 2004.

The rationale behind such a ban would be to reduce access to the types of gúns that would make it easy for one person to kill many people quickly. The 1994 ban placed restrictions on firearms that had certain characteristics of military weapons—for example, rifles with bayonet lugs, flash suppressors and pistol grips. Some gun enthusiasts derided the 1994 ban as a “cosmetic ban” because it prohibited certain guns that looked dangerous, while allowing other, equally deadly weapons to remain legal.

Whether you support Senator Feinstein’s bill or not, it’s important to understand what she proposes to ban, and it would be easier to assess the relevance of such a ban if the bill logically differentiated among weapons based on their capacity to kill. Most Americans know enough about guns to have formulated at least a vague opinion about what should and shouldn’t be legal. Through popular television programs, movies and video games, even people who have never fired a gun have developed some notion about the difference between, say, an M-16 and a snub-nosed revolver. But there are a huge variety of guns sold on the civilian market in the U.S., many of which are not well understood by the general public. This overview, while not comprehensive, is designed to clarify the significant differences between various types of firearms, with an emphasis on the weapon’s potential to kill many people quickly.

Much of the recent debate about which guns to ban has emphasized differences between handguns and rifles. That distinction is more complex than it might seem. We think of handguns as smaller weapons that shoot smaller bullets1. But some pistols have the same caliber, rate of fire and capacity as military rifles. At close range, specialized handguns can be as effective as rifles, either when used for hunting or when used to inflict mass casualties. In 2007, Seung-Hui Cho shot 49 people (32 fatally) at Virginia Tech, armed only with handguns.

A semiautomatic handgun with a high-capacity magazine. Photo © Matt Valentine

A semiautomatic handgun with a high-capacity magazine. Photo © Matt Valentine

Rather than focus on the size of the gun, I’d like to highlight two more relevant factors that make some guns more lethal in mass shooting scenarios than others, which are A) rate of fire and B) capacity. Any gun can be deadly, but all other things being equal, a gun that can fire rapidly for a sustained period without needing to be reloaded clearly has the potential to kill more people than a gun that can only be operated with frequent pauses. More »