Assault weapons and large capacity magazines allow even novice shooters to fire dozens of rounds within seconds. These types of firearms and accessories have been used in our nation’s deadliest shootings. They are designed for one purpose — to kill as many humans as possible as quickly as possible. They must be banned for civilian use.


An “assault rifle” is a firearm with certain features that make it easier to accurately shoot many bullets in a short amount of time. There are three key features that distinguish whether a firearm is an assault rifle: 

  1. Semi-automatic (meaning you do not need to reload after each shot);
  2. The ability to accept a detachable magazine;
  3. One or more additional features, such as a pistol grip or thumb hole stock that give the shooter the ability to keep the barrel on the target through dozens of rounds.

Military features which enhance control

Unlike traditional rifles, the structure and mechanisms of assault weapons mirror military firearms. They have features like pistol grips, second hand grips, or barrel shrouds, that make the gun easier to hold with two hands. This allows the shooter to control the gun for long periods of sustained fire without getting burned as the barrel heats up. These features, most of which were specifically designed for the military, are unnecessary for hunting, target shooting, or home defense. 

Detachable magazines

Detachable magazines give guns practically unlimited capacity. The number of cartridges a detachable magazine can hold is not limited by the size of the gun, because the magazine can extend well beyond the frame. Detachable magazines are readily available for most semi-automatic guns, making both military-style and non-military-style weapons more lethal. Detachable magazines are especially lethal when used with a military-style firearm that has features that allow the shooter to have enhanced control while firing multiple rounds.

What is a large capacity magazine?

A large capacity magazine is a magazine used in any type of firearm that has an overall capacity of, or can be converted to accept, more than 10 rounds of ammunition

These magazines allow shooters to fire numerous rounds — in some cases as many as 100 — without having to reload. Both handguns and military-style rifles can be equipped with large capacity magazines. Mass shootings have been thwarted by law enforcement or citizens when the shooter takes time to reload a cartridge. For example, in the 2011 Tucson shooting which killed six people and wounded thirteen others, including Congresswoman Gabrielle Giffords, the shooter was stopped by civilians as he attempted to reload his pistol.3 Similar shooters were disarmed by fellow citizens in the 2014 shooting at Seattle Pacific University4 and the 2018 shooting at the Waffle House in Nashville,5 among others.6

Large capacity magazines offer little value to responsible sportsmen. They pose a danger to all Americans, increasing the lethality of both mass shootings and daily gun violence. 

Dayton, Ohio, 2019

In August 2019 in Dayton, Ohio, a man used an assault weapon paired with a 100-round large capacity magazine to fire at a crowd killing nine people and wounding 27 others in just 32 seconds.6


While there are various models of assault weapons marketed to the public, these guns were first designed as a weapon for Soviet soldiers (AK-47) in the 1950s. These military assault weapons were lighter and easier to control than their bigger and heavier predecessors while maintaining their high firepower. This balance was achieved by using smaller cartridges and large-capacity magazines while retaining design features (like pistol grips, barrel shrouds, or forward hand grips) necessary to control the gun during sustained fire. These lightweight, easy-to-use, deadly weapons became the most common military firearm across the globe.8

In the 1980s, after experiencing declining gun sales, firearm manufacturers began marketing these military-style weapons directly to the American public. Gun manufacturers modified these weapons of war to sidestep federal law that prohibits fully automatic guns. They did this by creating firearm models that were virtually identical to those used in war but that did not have a fully automatic mode. For example, the semi-automatic AR-15 is the civilian counterpart to the fully-automatic M16 which is commonly used by the U.S. military, and there are numerous civilian equivalents to the AK-47. 

For more information on the history of assault weapons and efforts to ban them see our fact sheet Assault Weapons in America: A Brief History and our 2003 report Killing Machines: The Case for Banning Assault Weapons.

Under federal law, who can currently own assault weapons and large capacity magazines? 

Currently, federal law allows any person over the age of 18 to purchase and immediately acquire assault weapons and large capacity magazines from a private firearms dealer, at a gun show, or online — no questions asked. Under federal law, a person can also buy these firearms from a licensed gun dealer after passing a background check. However, it is important to note that many state laws restrict or ban assault weapons and/or large capacity magazines.


Use in mass shootings 

Assault weapons are often the weapon of choice for mass shooters because they allow killers to fire off dozens of rounds in a matter of seconds without stopping to reload. Assault weapons and firearms equipped with large capacity magazines have been used in some of the deadliest mass shootings in the United States, with one study estimating assault weapons accounted for nearly 86% of the mass-shooting fatalities reported from 1981-2017.9 Further, it is estimated that large capacity magazines are involved in half to two-thirds of public mass shootings and firearm mass murders involving six more fatalities.10 Shootings involving these weapons often result in more shots fired, more people wounded, and more wounds per victim compared to attacks with other firearms.11 An investigation of mass shootings from 2000-2017 found that incidents where semi-automatic rifles were used resulted in 97% more fatalities and 81% more wounded victims when compared to incidents where these deadly weapons were not used.12

Use in Community Gun Violence

Large capacity magazines are routinely used in handguns, and they help fuel the daily gun violence in impacted communities — specifically within communities of color in cities. A 2018 study examined the types of crime guns recovered by law enforcement in ten different cities and found that assault weapons and semiautomatic guns outfitted with large capacity magazines generally accounted for between 22 to 36% of crime guns recovered by police.10 This study illustrates how large capacity magazines are often used to inflict daily carnage within our communities. By using a large capacity magazine handgun, or in some cases an assault weapon, shooters can spray bullets through neighborhoods repeatedly shooting victims and increasing the likelihood that stray bullets hit bystanders.

Use in the killing of law enforcement officers

Assault weapons and large capacity magazines are also often used to kill law enforcement officers. The high rate of sustained fire puts law enforcement at an increased risk of injury or death. Forty percent of police officers who were murdered from 2009-2013 were murdered by a firearm equipped with a large capacity magazine including 13% of law police officers murdered by an assault weapon.13

Assault weapons used to shoot police officers: two cases from Pennsylvania

On April 4, 2009, three Pittsburgh officers were shot and killed in a shootout which lasted four hours. The gunman used an AK-47 assault weapon to carry out his planned attack.12

On August 14, 2019, six Philadelphia police officers were shot in an hours-long standoff with a man armed with an AR-15 assault weapon.12

America’s Weak Gun Laws Fuel Violence in Latin America and the Caribbean

Assault weapons and large capacity magazines are routinely trafficked over the U.S. border into Mexico and throughout Latin American and the Caribbean. These weapons, which are illegal for civilian use in Mexico and many Latin American and Caribbean countries, fuel extremely large levels of gun violence. In Mexico, for example, the expiration of the U.S. 1994 federal assault weapons ban coincided with an influx of trafficked assault weapons, a spike in cartel violence, and political instability.16 More than 20,000 Mexicans were murdered by a gun in 2018 — nearly seven times as many as in 2003 before the federal assault weapons ban expired.17 Weapons trafficked from the United States account for a large portion of these gun homicides with an estimated 70% of all guns recovered at crime scenes in Mexico originating from the United States. Unlike crime guns recovered in the United States,18 assault weapons are often responsible for fueling much of gun violence in Mexico. For example, one study found that seven out of the ten most commonly recovered crime gun models in Mexico were assault weapons which would have been banned under the federal assault weapons ban, and all of the ten models were capable of being outfitted with large capacity magazines.19 The Mexican military recovered over 12,000 assault weapons at crime scenes between 2006 and March 2018.20 Likewise, they recovered 112,000 large capacity magazines from crime scenes from 2011 to June 2019.21

Countries across Latin America and the Caribbean have faced an equally devastating impact of gun violence exacerbated by assault weapons and large capacity magazines trafficked from the United States. For example, the U.S. supplies nearly half of all guns found at crime scenes in El Salvador and 60% of all crime guns in Jamaica22 — these two countries have the two highest homicide rates in the world.23 The proliferation of assault weapons as a result of weak laws within the United States is linked to gun violence in countries across the globe, and Americans are partly responsible for this bloodshed.


In 1994, after a string of mass killings committed by criminals with assault weapons, Congress passed a law banning certain assault weapons and large capacity magazines. The 1994 law relied upon the model-designation approach, banning both specific assault weapons and “copies or duplicates . . . in any caliber” of those weapons.24 In addition, the law outlawed semi-automatic rifles and pistols that could accept a detachable magazine and included two or more specified features (referred to as the two-features test). Guns that were legally possessed before the effective date of the law remained legal. This ban was supported by Democrats and Republicans alike, including former presidents Gerald Ford, Jimmy Carter, Ronald Reagan, and sitting president Bill Clinton.25

Despite its overwhelming support among the public, the federal assault weapons ban only passed with the inclusion of a sunset provision, which allowed the bill to automatically expire after 10 years. In 2004, when Congress failed to act to continue the ban, assault weapons and large capacity magazines again became legal under federal law. 

Advocates and policymakers continue to push for an new assault weapons ban

Members of Congress have continued to introduce legislation to reinstate and strengthen the federal assault weapons ban since the expiration of the law. All of these efforts have thus far failed to pass despite consistent support from the American public and a series of high profile mass shootings carried out with assault weapons. 29


The 1994 law included several loopholes that gun makers and dealers exploited to continue making and selling assault weapons that Congress intended to ban. As a result, many assault weapons remained available.

Some gun companies made inconsequential design changes (like altering a cosmetic feature or replacing a flash suppressor with a “muzzle brake”) and gave the gun a new name. The new name exempted the gun from the prohibited list, and the minor change arguably put it out of reach of the law’s “copies or duplicates” language. For example, the banned TEC-9 became the legal AB-10.26

Also, some gun companies copied assault weapons that were originally made by other manufacturers. For example, Bushmaster’s XM15 was a copy of the banned Colt AR-15, with one minor design change. Functionally equivalent in all relevant respects to its banned cousin, the XM15, like innumerable other AR-15 variants, remained legal.27 The DC-area sniper allegedly used a new Bushmaster XM15 to shoot 13 victims, killing 10 in 2002.28

Finally, because the 1994 law allowed the continued ownership and sale of “pre-ban” assault weapons, those weapons remained available. These same loopholes exist in many state-level assault weapons bans.

“AR-15s and other semi-automatic assault weapons have become the official weapons of mass tragedy. They are chosen by shooters because they kill as many people as possible in a matter of minutes. The shooter in Dayton killed nine people and injured 26 others in less than a minute before being killed by police. This is not what James Madison intended when he wrote the Second Amendment. […] These weapons have no place at our food festivals, our shopping centers, our night clubs. Enough is enough.”

- CSGV statement after the mass shootings in El Paso, Texas and Dayton, Ohio.


State Assault Weapons Bans30

Seven states and the District of Columbia have enacted state level assault weapons bans. States with assault weapons bans include: California, Connecticut, Hawaii, Maryland, Massachusetts, New Jersey, and New York.

State Large Capacity Magazine Bans31

Nine states and the District of Columbia have enacted large capacity magazine bans. These states include: California, Colorado (limit of 15 rounds), Connecticut, Hawaii, Maryland, Massachusetts, New Jersey, New York, and Vermont (limit to 15 rounds for handguns).

States that have banned assault weapons and/or large capacity magazines

  • Large capacity magazine ban
  • Assault weapons ban and large capacity magazine ban

State level bans

State level assault weapons and large capacity magazine bans play an important role in reducing the number of weapons of war in our streets and helping to prevent gun violence. Growing evidence suggests large capacity magazine bans in particular have had a positive impact on reducing mass shootings. Large capacity magazine bans have been found to reduce both the incidence of — and the number of people killed in — high-fatality mass shootings.31 States with large capacity magazine bans are estimated to have had 48% fewer high-fatality mass shootings from 1994-2017.32

One reason why banning large capacity magazines is effective at preventing gun fatalities is because of the lethality of the accessory. Large capacity magazines allow a shooter to fire many rounds without ever having to stop to reload. Research shows that victims struck by multiple ammunition rounds are more likely to die. The fatality rate of a victim hit by more than one bullet was more than 60% higher when compared with fatality rates of gunshot wound victims who were hit by one bullet.34 Shootings using large capacity magazines resulted in a 60-67% higher average death toll.33

However, the open borders between states invite gun traffickers to evade the law in one state by importing assault weapons from other states. Therefore, state level assault weapons and large capacity magazine bans are not enough. Congress must reinstate a strong federal assault weapons ban now to keep our communities free from these weapons of war.

Gilroy, California, 2019

Despite California’s ban on assault weapons and large capacity magazines, a man was able to drive into Nevada buy an assault weapon, a 75-round, and five 40-round large capacity magazines and use this weapon to kill 3 and wound 17 in a matter of minutes. Tragedies like these highlight the need for a federal assault weapons ban.34

Federal ban

As mentioned above, the federal assault weapons ban had loopholes that were exploited by gun manufacturers. Likewise, the ban only lasted ten years and there were many assault weapons already in circulation. These two elements likely weakened the impact of the federal assault weapons ban.35

There is, however, increasing evidence the federal assault weapons ban did reduce the use of large capacity magazines in crime, as well as the number of mass shooting deaths.

Reduced use of large capacity magazines 

An analysis of crime guns in Virginia found that the rate of large capacity magazines guns collected by police decreased while the federal ban was in place but then rose sharply after the ban expired.36

In Richmond, Virginia, for example, the use of large capacity ammunition magazines in gun crimes decreased by nearly 50% during the ban but then returned to pre-­ban levels after the ban expired.37 Researchers found this similar trend in a number of states, suggesting that the ban curbed the use of guns outfitted with large capacity magazines.38

Reduced police killed by large capacity magazines

This proportion of large capacity magazine equipped guns used to kill police increased by 30% after the assault weapons ban when more large capacity magazines were in circulation.39

Reduced mass shooting deaths

Research suggests that the federal assault weapons ban was effective in reducing the number of deaths from mass shootings. For example, one study found that mass shooting deaths were 70% less likely to have occurred during the years when the federal assault weapons ban was in place.40

Similarly, a 2019 analysis conducted by economist John Donohue at Stanford University examined gun massacres over a 35-year period (as they are defined by the FBI). He found that the federal assault weapons ban was associated with a 25% drop in gun massacres and a 40% drop in fatalities that occurred at gun massacres compared to the decade before it’s adoption. This same analysis found that in the decade after the ban there was a 347 percent increase in fatalities in gun massacres, even as overall violent crime continued downward.41

During the decade from 1994-2004 when the federal assault weapons ban was in place, only one of the 20 deadliest mass shootings in American history occurred. In the 15 years since the assault weapons ban expired (October 2004- October 2019), 16 of the 20 deadliest mass shootings have occurred. Twelve of these mass shootings were carried out by a shooter who used an assault weapon and/or large capacity magazine, accounting for 314 casualties.42

All five of the deadliest mass shootings in American history occurred since Congress let the federal assault weapons ban expire, and all of these shootings involved weapons that would have previously been banned under federal law.43

Fatalities from the 20 Deadliest Mass Shootings in Modern American History


Assault weapons/Large capacity magazines used
Assault weapons/Large capacity magazines not used

Source: Analysis based on data compiled from Follman, Gavin et al. (2020).


For years, an overwhelming majority of Americans have recognized that assault weapons have no place in our communities or on our streets. Polling conducted over the past seven years (2015, 2017, 2019) shows that over 60 percent of Americans consistently favor a ban on assault weapons and on large capacity magazines.44,45 A 2019 poll conducted in the wake of a series of mass shootings found that as many as 70% of Americans support a federal assault weapons ban including a majority of Republicans (55%), gun owners (57%), and military members (65%).46 Yet, despite this stable, widely shared view, assault weapons and large capacity magazines remain legal and easy to buy, often with no questions asked.


Reinstate the federal ban on assault weapons and large capacity magazines. In the absence of federal action, states should continue to enact assault weapons and large capacity magazine bans.

Congress should ban the importation, sale, manufacture, transfer, and possession of assault weapons and large capacity magazines. Weapons currently possessed should be classified as Class III items under the National Firearms Act and regulated by the ATF. An assault weapons ban should incorporate a one-feature test (rather than the two-feature test used in the 1994 Assault Weapons Ban), which would ban semi-automatic pistols and rifles that have the capacity to accept a detachable magazine and have any single military-style feature, as well as ban semi-automatic shotguns with any single military-style feature. Congress should allow federal funds to be used in voluntary buy back programs.

A large capacity magazine is a magazine used in any type of firearm that has an overall capacity of, or can be converted to accept, more than 10 rounds of ammunition. These magazines allow shooters to fire numerous rounds — in some cases as many as 100 —without having to reload. Congress should ban the importation, sale, manufacture, and transfers of large capacity magazines.

As long as the federal government fails to act in reinstating a federal ban, states should continue to enact assault weapons and large capacity magazine bans that apply in their jurisdictions.


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Last updated July 2020