Large-Capacity Magazines and the Casualty Counts in Mass Shootings

• Date: 01 June 2016
• Published date: 01 June 2016
• DOI: 10.1177/1525107116674926
• Subject Matter: Research Articles

Research Article

Large-Capacity Magazines

and the Casualty Counts

in Mass Shootings: The

Plausibility of Linkages

Gary Kleck

1

Abstract

Do bans on large-capacity magazines (LCMs) for semiautomatic firearms have sig-

nificant potential for reducing the number of deaths and injuries in mass shootings?

The most common rationale for an effect of LCM use is that they allow mass killers to

fire many rounds without reloading. LCMs are known to have been used in less than

one third of 1% of mass shootings. News accounts of 23 shootings in which more than

six people were killed or wounded and LCMs were known to have been used,

occurring in the United States in 1994–2013, were examined. There was only one

incident in which the shooter may have been stopped by bystander intervention when

he tried to reload. In all of these 23 incidents, the shooter possessed either multiple

guns or multiple magazines, meaning that the shooter, even if denied LCMs, could have

continued firing without significant interruption by either switching loaded guns or

changing smaller loaded magazines with only a 2- to 4-seconds delay for each magazine

change. Finally, the data indicate that mass shooters maintain such slow rates of fire

that the time needed to reload would not increase the time between shots and thus

the time available for prospective victims to escape.

Keywords

mass shootings, gun control, large-capacity magazines

1

College of Criminology and Criminal Justice, Florida State University, Tallahassee, FL, USA

Corresponding Author:

Gary Kleck, College of Criminology and Criminal Justice, Florida State University, Tallahassee, FL 32306,

USA.

Email: gkleck@fsu.edu

Justice Research and Policy

2016, Vol. 17(1) 28-47

ªThe Author(s) 2016

Reprints and permission:

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DOI: 10.1177/1525107116674926

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Introduction—Mass Shootings and Large-Capacity

Magazines (LCMs)

There have been at least 23 shootings in which more than six victims were shot and

one or more LCMs were known to have been used in the United States in the period

1994–2013. One of the most common political responses to mass shootings has been

to propose new gun control measures, commonly focusing on ‘‘assault weapons’’ and

LCMs. LCMs are detachable ammunition magazines used in semiautomatic firearms

that are capable of holding more than a specified number (most commonly 10 or 15)

rounds. For example, the 1994 federal assault weapons ban prohibited both (a) certain

kinds of guns defined as assault weapons and (b) magazines able to hold more than

10 rounds (Koper, 2004). At least eight states and the District of Columbia similarly

ban magazines with a large capacity, and still other states are considering bills to enact

such restrictions (Brady Campaign to Prevent Gun Violence, 2013).

Theory—The Rationale for LCM Bans

When supportersof bans on LCMs provide an explicitrationale for these measures, they

stress the potential for such restrictions to reduce the death toll in mass shootings. And

indeed thereis a statistical associationbetween LCM use and the casualty count in mass

shootings(Koper, 2004), thoughit is unknown whetherthis reflects aneffect of LCM use

or is merely a spurious association reflecting the offender’s stronger intention to harm

many people.If there is a causal effect, how wouldit operate? Does possessionof LCMs

somehowenable aggressorsto shoot morevictims, above and beyondthe ability conferred

by the use ofsemiautomatic guns equipped with smallercapacity detachablemagazines?

(A semiautomatic firearmis a gun that fires a singleshot for each pullof the gun’s trigger,

but automatically causes a freshround to be loaded into the gun’s firing chamber.)

Possession of LCMs is largely irrelevant to ordinary gun crimes, that is, those with

fewer victimsthan mass shootings, becauseit is extremely rare thatthe offenders in such

attacks fire more rounds than can be fired from guns with ordinary ammunition capa-

cities. For example, only 2.5%of handgun crimes in Jersey City, NJ, in 1992–1996

involved over 10 rounds being fired (Reedy& Koper, 2003, p. 154). Even among those

crimes in which semiautomatic pistols were used, and some of the shooters were

therefore likely to possess magazines holding more than 10 rounds, only 3.6%of the

incidents involved over 10 rounds fired.Thus, if LCMs have any effect on the outcomes

of violentcrimes, it is more likely to be foundamong mass shootings with manyvictims,

which involve unusually large numbers of rounds being fired.

Koper (2004) noted that ‘‘one of the primary considerations motivating passage of

the ban on [LCMs]’’ was the belief that

semiautomatic weapo ns with LCMs enable offenders to fir e high numbers of shots

rapidly, thereby potentially increasing both the number of persons wounded per gunfire

incident ...and the number of gunshot victims suffering multiple wounds, both of which

would increase deaths and injuries from gun violence. (p. 80)

Kleck 29