Introduction

Restrictions on high‐​capacity magazines come either on their own or as a component of “assault weapon” legislation. They focus on detachable firearm magazines capable of holding more than a certain number of cartridges. The Federal Assault Weapons Ban of 1994, for instance, included limitations on magazines that could hold more than 10 rounds.

For law‐​abiding Americans, firearms are tools of recreation and self‐​defense. Defensive uses of firearms can preserve human life. Americans use firearms with magazine capacities of 10 to 30 rounds for the same reason law enforcement officers do: because they are effective tools for defensive use. For this reason alone, magazine restrictions should be understood as restrictions on weapons themselves and should thus be taken as seriously and subject to as much scrutiny as restrictions directly on firearms.

Currently, eight states, the District of Columbia, and a number of municipal governments ban or heavily regulate magazines that they have defined as “high capacity.” Typical state bans set a limit of 10 rounds per magazine, although some limit capacity to 15. Some municipalities are more restrictive: New York City, for example, restricts magazine capacity for long guns to 5 rounds, stricter than the limit of 10 rounds for long guns and pistols in the rest of the state. Most jurisdictions allow magazines owned prior to the law to be grandfathered in, but some do not. New York had previously attempted to set the limit at 7 rounds — possession of 10‐​round magazines was allowed, yet loading them beyond 7 rounds was forbidden — but that law was ruled unconstitutional. The court found that the provision was “untethered from the stated rationale of reducing the number of assault weapons and large capacity magazines in circulation.”

In mid‐​2017, Judge Roger T. Benitez of the United States District Court for the Southern District of California blocked Proposition 63, a law that would have effectively banned the possession of magazines capable of holding more than 10 rounds. According to Judge Benitez, California, in justifying its ban, referred to a “homogenous mass of horrible crimes in jurisdictions near and far for which large capacity magazines were not the cause.” Although courts have generally treated the right to keep and bear arms as second class and have consistently accepted state justifications for gun control, Judge Benitez subjected the state’s claims to a more critical inquiry. As he rightly pointed out, “the phrase ‘gun violence’ may not be invoked as a talismanic incantation to justify any exercise of state power.”

California’s Proposition 63 joins the ranks of several other magazine restrictions that have been contested through the various courts of appeals with mixed results. Earlier in the year, Maryland’s “assault weapon” bans — which included a magazine restriction of 10 rounds — were upheld by the Fourth Circuit in Kolbe v. Hogan, and the Supreme Court declined to review the case in November of 2017.

Clearing Up Functional and Technical Issues

There are many misconceptions about magazines that must be corrected before there can be a coherent discussion about whether and how to restrict them. Four commonly misunderstood points stand out. First, the term “high‐​capacity” does not have a precise definition. Second, a magazine’s capacity can vary based on the ammunition that is used. Third, an effective magazine is more than “just a box” for cartridges. And fourth, almost every gun that can accept a magazine is capable of accepting a high‐​capacity magazine, however defined; thus, it is a mistake to characterize weapons that are merely capable of using high‐​capacity magazines as particularly dangerous.

“High‐​Capacity” Is a Relative Term

Most pistols sold in the United States come equipped with magazines that hold between 10 and 17 rounds. In fact, those holding 10 rounds are generally compact or subcompact models. Full‐​size pistols, like those commonly used by law enforcement officers, overwhelmingly ship with 12- to 20‐​round magazines as standard. And the most common self‐​loading rifles in the United States have a standard magazine capacity of between 20 and 30 rounds.

By the end of 2017, however, eight states and the District of Columbia had some sort of restriction or ban based on magazine capacity, and several set the limit at 10 rounds. If anything is arbitrary, it is these limits, since they do not comport with the normal gun market. Those states ban as “high‐​capacity” the “normal‐​capacity” magazines that come shipped with the gun and are in common use in the rest of the country.

A Magazine’s Capacity Can Vary

Magazines can often be used for multiple calibers of cartridge, and the number of rounds they can hold depends on the caliber. For example, a certain magazine often affiliated with the AR-15 will hold 30 rounds of 5.56 mm ammunition but only 10 rounds of the larger .458 SOCOM ammunition. Many popular magazines have similarly variable capacities. This variability presents a tremendous practical issue with regard to regulating magazine capacity. How is the line to be drawn? Should the same magazine be legal or illegal depending on the cartridge used? Should firearm owners have to use half‐​full magazines of a certain caliber to comply with the law?

As an example, in 1991 the Canadian government limited the magazine capacity for self‐​loading rifles to five rounds. The Canadian law focuses on what the magazine is “designed” for, which creates some odd situations. A magazine “designed” for 5 rounds of 50 caliber ammunition can still practically — and legally — be loaded with 15 rounds of 5.56 mm ammunition. But putting that same amount of ammunition into a magazine marked for 15 rounds of 5.56 mm ammunition — a magazine which is identical to the former in all ways but markings — could result in jail time. It is hard to square this result with the intent of the law, but the technical characteristics of magazines require such distinctions to be made.

A Magazine Is Not “Just a Box”

The misconception that a magazine is “just a box” into which rounds are stuffed is often heard from opponents of magazine restrictions. They claim that magazines, if banned, could be easily fabricated, which would allow criminals to easily avoid restrictions and would leave law‐​abiding citizens to face the most severe consequences of a ban. Although it is true that black‐​market access to restricted magazines will always be easy, this is not because magazines are easy to make but rather because of the tremendous number of magazines already in circulation.

Rather than being just boxes, magazines are complex and finely tuned. That complexity is why many early magazine rifles had their magazines chained to the rifle and why most countries avoided the use of detachable magazines into the 20th century. Even today, a large proportion of handgun magazines are manufactured by a single Italian company, Mec‐​Gar, because of how difficult it is to get the design right.

A magazine is an essential and deceptively complicated component of a self‐​loading firearm. In fact, magazine malfunctions are the primary source of breakdowns in self‐​loading weapons. Every detachable magazine requires a tremendous amount of complex engineering. Tiny inconsistencies in the angle of the feed lips, the spring tension, the wall thickness, or other components of the magazine can render a firearm nonfunctional. Any properly informed discussion of magazine restrictions must take this fact into account.

Almost Every Gun Is “Capable of Accepting” a High‐​Capacity Magazine

Certain laws, many of which are based on the federal Public Safety and Recreational Firearms Use Protection Act of 1994, proscribe weapons that are “capable of accepting” a large‐​capacity magazine, however defined. This language is particularly concerning because magazines exist separately from the gun. If an otherwise allowable firearm is designed for use only with 10‐​round magazines, and a third party constructs a single 20‐​round magazine, does that render the firearm forbidden? If so, every gun for which the physical characteristics of that magazine allow it to be used would now be capable of accepting the new magazine, regardless of how many such magazines actually existed. In fact, there are many weapons that were designed to use magazines only of a certain size but are capable of accepting larger‐​capacity magazines built by either third‐​party manufacturers or hobbyists.

Language so vague that it invites endless speculation should be avoided in law. A detachable magazine, by its nature, fits into an opening of a particular shape. Any law that refers to weapons “capable of accepting” a large‐​capacity magazine may just as well refer to the entirety of magazine‐​accepting weapons. There is no meaningful distinction between the two groups.

Sometimes studies purport to demonstrate a connection between weapons “capable of” accepting high‐​capacity magazines (however defined) and violent crime. Yet this is evidence only of popularity, not of lethality. Firearms that are affordable and in common use are more likely to show up at crime scenes, as are firearms that are fashionable with certain groups of criminals, such as Glock pistols. The same reasoning could apply to black guns. Given that many guns are black, a similar study would presumably show that a significant percentage of guns used in crimes were black. Would it be rational, from this information, to propose banning black guns?

All guns are potentially dangerous and lethal, but except in rare mass shooting situations, as discussed below, increased ammunition capacity is rarely a factor in gun crimes. Although it may be true that the use of extended magazines in handguns is correlated with an increase in crime — possibly because of the fad of pistols with “stendos,” a slang term for extended magazines — this is more about gang‐​appreciated aesthetics than about actual lethality. If such magazines disappeared, gang‐​related violence would certainly not go with them.

Legal Background and Constitutional Concerns

As recognized in District of Columbia v. Heller, the Second Amendment protects an individual’s right to keep and bear arms. By implication, that right is not limited to guns but extends also to the ammunition and magazines that make guns operable. The Court also held that the Second Amendment protects arms in “common use,” which would cover the 20‐​round magazines that are standard equipment for a significant portion of weapons currently in lawful use. Although banning some “novelty magazines,” such as the 100‐​round Beta C‐​Mag — unpopular because of its weight, expense, and propensity to jam — might be constitutional, there is no legitimate constitutional argument for removing common magazines from the scope of Second Amendment protection.

In response, proponents of magazine restrictions often argue that Founding‐​era weapons did not typically carry more than 10 cartridges. More broadly, they cite language in Heller that seems to permit some restrictions on firearm ownership. Both arguments reach too far.

The Supreme Court has said that the Second Amendment extends to all instruments that constitute bearable arms in common use, even those that were not in existence at the time of the Founding. The contention that the Constitution’s scope is in any way limited to the arms that existed in the 18th century was rejected as “bordering on … frivolous[.]” In fact, handguns and carbines carrying more than 10 rounds were fairly common well before the Fourteenth Amendment was ratified in 1868, after which the Second Amendment arguably applied against the states, and before that, no one had thought that states could restrict the natural right to have such arms.

Regarding the broader claim that the Second Amendment allows some regulation, Justice Antonin Scalia does in fact mention “presumptively lawful regulations” such as those concerning “M-16 rifles and the like.” But including firearms and magazines in common lawful use today under such regulations raises two issues. First, “M-16” is a specific military designation. Unlike “AR-15,” which refers to a “pattern” of rifle of which there are hundreds of derivatives, “M-16” refers to a particular machine gun (i.e., a fully automatic weapon that fires continuously with a single trigger pull) regulated by the 1934 National Firearms Act. Second, Scalia’s language needs to be read in the larger context of the opinion, which holds that the Second Amendment protects all arms in common lawful use. M‐​16s are not in common lawful use; 15- to 30‐​round magazines undoubtedly are.

Ill‐​Defined, Unproven, and Ineffective: The Substantial Costs of Magazine Restrictions

“High‐​capacity” magazine restrictions are billed as safeguards of public safety aimed at combating pervasive problems with “gun violence.” Yet there is little evidence that such laws have any appreciable impact on public safety, much less enough positive impact to justify the substantial human cost attendant in their enforcement.

One can always conceive of such benefits, of course. We might imagine, for example, that a magazine capacity low enough to force constant reloading would hinder mass shooters. But even if that were true, we would need to ask whether such benefits would justify the costs, such as the attendant restrictions on the right to self‐​defense. And who would likely be affected by such laws — criminals and mass shooters or law‐​abiding gun owners? Magazine restrictions are often written as strict liability offenses, meaning that there is no defense for violating the law, even if violators do not know they possess an illegal magazine (say, if a friend had left one in their car). Moreover, in states such as California and Maryland, the mere shape of a magazine can make criminals out of those who have one in their possession or control. Such laws might be used against mass shooters and murderers, but they will also be used against parents who use slightly noncompliant weapons in self‐​defense, or history‐​buff hobbyists or collectors who want particular pieces for their collections, or potential victims of domestic violence who live in states that restrict magazines to six or seven rounds.

An Ineffective Solution

Magazine restrictions do not have appreciable effects on crime or violence. In an oft‐​cited study, Christopher Koper analyzed the effects of the 1994 Federal Assault Weapons Ban, which banned new magazines of more than 10 rounds but did little more than drive up the price of already‐​existing magazines. While presenting his findings at a Johns Hopkins summit on reducing gun violence in America, Koper was decidedly noncommittal on the ban’s utility.