Assault Weapons and High-Capacity Magazines

Introduction

Assault weapons and high-capacity magazines are uniquely dangerous. The most common assault weapons¹Generally, most current state laws define “assault weapons” as semiautomatic firearms that have a number of military-style features, semiautomatic firearms that come equipped with fixed high-capacity magazines, or other specifically enumerated high-powered firearms. are generally semiautomatic rifles that fire bullets with up to four times the muzzle velocity of a handgun round.²Peter M. Rhee et al., “Gunshot Wounds: A Review of Ballistics, Bullets, Weapons, and Myths,” Journal of Trauma and Acute Care Surgery 80, no. 6 (June 2016): 853–67, https://doi.org/10.1097/TA.0000000000001037. This means that each round from an assault weapon inflicts greater damage to the human body than a round from a typical handgun.³Rhee et al., “Gunshot Wounds.” Moreover, semiautomatic weapons can load and fire subsequent rounds much faster than manually operated firearms. When combined with high-capacity magazines—commonly defined as magazines capable of holding more than 10 rounds of ammunition—they allow a shooter to fire more rounds over a short period without pausing to reload. The more rounds a shooter can fire consecutively, the more gunshot wounds they can inflict during an attack.⁴Elzerie de Jager et al., “Lethality of Civilian Active Shooter Incidents with and without Semiautomatic Rifles in the United States,” JAMA 320, no. 10 (2018): 1034, https://doi.org/10.1001/jama.2018.11009.

Even though the high power of assault weapons and high-capacity magazines are proven to result in far higher casualty counts, there has been no federal restriction on access to and possession of these weapons for almost two decades. In 1994 Congress passed a law prohibiting the manufacture, transfer, or possession of certain semiautomatic assault weapons and high-capacity magazines. Because this law had a sunset provision after one decade and was not renewed by Congress after this period, the prohibition on assault weapons and high-capacity ammunition magazines was in effect over the period from September 1994 to September 2004.⁵Public Law 103-322, Title XI (1994). Part of the Violent Crime Control and Law Enforcement Act of 1994, the Public Safety and Recreational Firearms Act prohibited semiautomatic assault weapons designated by specific make or model or by a combination of specific characteristics, such as a folding or telescopic stock or a pistol grip that extends below the action of the weapon (former 18 USC § 921(a)(30)(B)). It also prohibited ammunition magazines with more than 10 rounds (former 18 USC § 921(31)). The law took effect September 13, 1994, and expired on September 13, 2004. Vivian S. Chu, “Federal Assault Weapons Ban: Legal Issues,” Congressional Research Service, February 14, 2013, https://sgp.fas.org/crs/misc/R42957.pdf. Prior to, during, and following the expiration of this federal law, a number of states and Washington, DC, enacted their own prohibitions on assault weapons and high-capacity magazines. While state-level laws help prevent mass shootings and gun crimes, without federal restrictions these weapons still remain accessible across the nation—contributing to recent deadly shootings.

Impact of Assault Weapons and High-Capacity Magazines on Gun Violence

Assault weapons and high-capacity magazines are frequently used in the crimes that plague our nation.

Although the gun lobby has argued that these weapons are only used in a small percentage of firearm-related violent crime, a 2018 study estimated that guns equipped with high-capacity magazines, which include assault weapons and other semiautomatic firearms, account for 22 to 36 percent of crime guns in most places, with some estimates upward of 40 percent for cases involving serious violence, including homicides of law enforcement officers. And the problem may be getting worse: research suggests that the prevalence of high-capacity magazines in guns used in crimes has grown substantially since the 2004 expiration of the federal prohibition on assault weapons and high-capacity magazines.⁶Christopher S. Koper et al., “Criminal Use of Assault Weapons and High-Capacity Semiautomatic Firearms: An Updated Examination of Local and National Sources,” Journal of Urban Health 95, no. 3 (2018): 313–21, https://doi.org/10.1007/s11524-017-0205-7.

High-capacity magazines allow shooters to fire more rounds without stopping to reload, inflicting more damage over a short period.

Recent shootings show that the high-powered rapid fire of assault weapons and high-capacity magazines can wound and kill many people very quickly: 

• A man shot 20 people, 11 fatally, at a Lunar New Year 2023 celebration when he began shooting at a dance studio in Monterey Park, California. He was armed with a Cobray M11 assault pistol, a homemade silencer, and a 30-round magazine.⁷Jeremy White and K.K. Rebecca Lai, “What We Know About the Gun Used in the Monterey Park Shooting,” New York Times, January 26, 2023, https://nyti.ms/3XPTGvZ; Emily Mae Czachor and Jordan Freiman, “What We Know About the Victims From the Monterey Park Shooting,” CBS News, January 25, 2023, https://cbsn.ws/3KJXs7p.
• On July 4, 2022, a young man armed with a Smith & Wesson AR-15-style rifle and three 30-round magazines opened fire at a parade in Highland Park, Illinois. He fired 83 rounds, shooting 55 people, seven fatally, in a matter of moments.⁸“Highland Park Parade Shooting: Investigators Release Photo of Gun Found in Robert Crimo’s Vehicle,” Fox 32 Chicago, July 6, 2022, https://bit.ly/3lQd6U9; Associated Press, “The Highland Park Shooting Suspect is Indicted on 117 Charges,” NPR, July 28, 2022, https://n.pr/3lZcVWv.
• In Uvalde, Texas, in 2022, an 18-year-old shot his grandmother before driving to Robb Elementary School to continue his rampage. Armed with a Daniel Defense AR-15-style rifle he purchased days after his 18th birthday and 30-round magazines, he shot 38 people, 21 fatally inside classrooms.⁹Texas House of Representatives, Investigative Committee on the Robb Elementary Shooting, “Interim Report, 2022,” July 17, 2022, https://bit.ly/3IoRIgi.
• A man entered a grocery store in Buffalo, New York, in 2022 with an illegally modified Bushmaster AR-15-style rifle and 30-round magazines. He opened fire, killing 10 people and wounding three.¹⁰Craig Whitlock, David Willman, and Alex Horton, “Massacre Suspect Said He Modified Bushmaster Rifle to Hold More Ammunition,“ Washington Post, May 15, 2022, https://wapo.st/3SkEe8N.
• In 2019, a shooter in Dayton, Ohio, used an AR-15-style assault pistol equipped with a 100-round drum magazine to shoot 26 people, nine fatally, in 32 seconds.¹¹Alejandro De La Garza and Michael Zennie, “Dayton Shooting Lasted Just 32 Seconds and Left 9 Dead. Here’s the Latest on the Tragedy,” Time, August 9, 2019, https://bit.ly/3vL7zQm; Emily Shapiro, “26 Shot in 32 Seconds: New Details, Videos Released in Dayton Mass Shooting,” ABC News, August 13, 2019, https://abcn.ws/2MfrPFb.   
• Armed with a Smith & Wesson AR-15-style rifle and 30- and 40-round magazines, the shooter at Marjory Stoneman Douglas High School in Parkland, Florida, in 2018 shot and killed 11 people and wounded 13 more in less than two minutes, and continued on to shoot 10 people, six fatally, in 45 seconds.¹²Marjory Stoneman Douglas High School Public Safety Commission, “Initial Report Submitted to the Governor, Speaker of the House of Representatives and Senate President,” January 2, 2019, https://bit.ly/37Gaoop; “Teen Gunman Kills 17, Injures 17 at Parkland, Florida High School,” History, February 14, 2018, ​​https://bit.ly/2XDCwax. 
• The shooter at the Pulse nightclub in Orlando, Florida, in 2016 at one point fired more than 20 rounds in nine seconds with a Sig Sauer AR-15-style rifle equipped with a 30-round magazine. By the end of his rampage, 102 people had been shot, 49 fatally.¹³Mia de Graaf and Jenny Stanton, “Snapchat Audio Captures Screaming Horror as Orlando Gunman Fired 24 Shots in Just 9 Seconds inside Nightclub Massacre,” Daily Mail, June 14, 2016, https://bit.ly/3pguyjf; Larry Buchanan et al., “What Is a Bump Stock and How Does It Work?” New York Times, March 28, 2019, https://nyti.ms/3w7JLaa. 

Assault weapons and high-capacity magazines are frequently used in mass shootings, resulting in more deaths and injuries.

The gun lobby has long downplayed the connection between assault weapons and mass shootings. However, at least one study of mass shooting incidents between 1981 and 2017 found that assault weapons accounted for 86 percent of the 501 fatalities reported in 44 mass shooting incidents.¹⁴DiMaggio et al., “Changes in US Mass Shooting Deaths.” Study defines a “mass shooting” as an incident in which four or more people, not including the shooter, are killed with a firearm. A more recent analysis of Everytown’s Mass Shootings in America database from 2009 through 2022 similarly reveals that there were at least 63 mass shootings¹⁵A mass shooting is defined as an incident in which four or more people, not including the shooter, are killed with a firearm. involving a firearm equipped with a high-capacity magazine, an assault weapon, or both, resulting in 582 people killed and 885 people wounded.

Between 2009 and 2022, mass shootings where an assault weapon was used accounted for a quarter of all mass shooting deaths and more than three-quarters of all injuries.¹⁶Analysis of Everytown’s Mass Shootings in America database, accessed January 20, 2023. From 2009 to 2022, there were at least 40 mass shootings (19 percent of those with known weapon data) that involved the use of an assault weapon, resulting in 424 people killed and 811 people wounded. Shootings where assault weapons were used resulted in over five times as many people shot, more than twice as many people killed, and 20 times as many people wounded per incident on average.¹⁷Analysis of Everytown’s Mass Shootings in America database, accessed January 20, 2023. From 2009 to 2022, the 40 mass shootings involving assault weapons resulted in an average of 30.9 people shot, 10.6 people killed, and 20.3 people wounded per incident, compared to an average of 5.8 people shot, 4.8 people killed, and 1.0 people wounded that resulted from the 253 incidents when other or unknown-type guns were used. Incidents involving a firearm equipped with a high-capacity magazine resulted in more than four times as many people shot, twice as many fatalities, and 14 times as many injuries per incident on average compared to those that did not involve the use of high-capacity magazines.¹⁸Analysis of Everytown’s Mass Shootings in America database, accessed January 20, 2022. From 2009 to 2020, the 51 incidents involving the use of high-capacity magazines resulted in 26.0 people shot, 10.1 people killed, and 15.8 people wounded on average per incident, compared to an average of 5.7 people shot, 4.6 people killed, and 1.1 people wounded on average that resulted from the 242 incidents that did not involve the use of high-capacity magazines or magazine capacity was undetermined.

The 10 mass shooting incidents with the most casualties during this period all involved at least one firearm equipped with a high-capacity magazine, and nine out of 10 involved the use of at least one assault weapon (These mass shootings occurred at a concert in Las Vegas, Nevada; a nightclub in Orlando, Florida; a movie theater in Aurora, Colorado; a parade in Highland Park, Illinois; a Walmart in El Paso, Texas; a military base in Fort Hood, Texas;¹⁹The mass shooting at Fort Hood is the only incident among these 10 that did not involve an assault weapon. The shooter used a handgun equipped with a high-capacity magazine. Investigators recovered multiple 30-round and 20-round high-capacity ammunition magazines at the scene. “Investigators Detail Ammo Found at Fort Hood Shooting Scene,” Dallas Morning News, October 21, 2010, https://bit.ly/3BmF1kg. a church in Sutherland Springs, Texas; an elementary school in Uvalde, Texas; a staff training event in San Bernardino, California; and a high school in Parkland, Florida).²⁰Las Vegas, NV, 471 people shot, 60 fatally; Orlando, FL, 102 people shot, 49 fatally; Aurora, CO, 82 people shot, 12 fatally; Highland Park, IL, 70 shot, seven fatally; El Paso, TX, 46 people shot, 23 fatally; Fort Hood, TX, 45 people shot, 13 fatally; Sutherland Springs, TX, 45 people shot, 25 fatally; Uvalde, TX, 38 people shot, 21 fatally; San Bernardino, CA, 36 people shot, 14 fatally; and Parkland, FL, 34 people shot, 17 fatally. Everytown for Gun Safety Support Fund, “Mass Shootings in America,” accessed January 20, 2023. This database defines a mass shooting as an incident in which four or more people, not including the shooter, are killed with a firearm.

A growing body of research shows that the decade-long federal prohibition on assault weapons and high-capacity magazines was effective in both preventing public mass shootings and reducing the number of fatalities and injuries when these tragedies occurred.

A 2021 study found that the federal prohibition on assault weapons and high-capacity magazines was associated with a significant decrease in public mass shootings and related casualties, preventing at least 11 public mass shootings during the 10 years it was in effect. The researchers also estimated that had the law remained in effect from 2005 through 2019, it would have prevented 30 mass shootings that resulted in the death of 339 people and wounded 1,139 more.²¹Lori Post et al., “Impact of Firearm Surveillance on Gun Control Policy: Regression Discontinuity Analysis,” JMIR Public Health and Surveillance 7, no. 4 (2021): e26042, https://doi.org/10.2196/26042. Study defined mass shooting as four or more victims killed with a firearm at a public location. Familicides and felony killings were excluded. Similarly, a 2019 study found that the law was effective in reducing mass shooting fatalities, and had the law continued, it would have prevented hundreds of mass shooting deaths.²²DiMaggio et al., “Federal Assault Weapons Ban.” Study defines a mass shooting as an incident in which four or more people, not including the shooter, are killed with a firearm.

State-level prohibitions can reduce mass shootings.

In the absence of federal action on this urgent issue, some states have taken action to prohibit high-capacity magazines. States with restrictions on magazine size experience mass shootings at less than half the rate of states without restrictions.²³Louis Klarevas, Andrew Conner, and David Hemenway, “The Effect of Large-Capacity Magazine Bans on High-Fatality Mass Shootings, 1990–2017,” American Journal of Public Health 109, no. 12 (2019): 1754-61, https://doi.org/10.2105/AJPH.2019.305311. Study defined mass shooting as six or more shot and killed, excluding the shooter; Sam Petulla, “Here Is 1 Correlation between State Gun Laws and Mass Shootings,” CNN, October 5, 2017, https://cnn.it/2J4sWCC. Study defines mass shootings as incidents where three or more victims, not including the shooter, are shot and killed or shot and wounded. In Virginia, for example, the federal law was associated with significant reductions in the share of guns used in crimes that were equipped with high-capacity magazines, down to an all-time low of 10 percent in 2004. After the federal prohibition expired, the share of Virginia crime guns equipped with high-capacity magazines rapidly increased, reaching 22 percent by 2010.²⁴ David S. Fallis and James V. Grimaldi, “Va. Data Show Drop in Criminal Firepower during Assault Gun Ban,” Washington Post, January 22, 2011, https://wapo.st/3Cugf0g. According to Dr. Michael Siegel, a researcher at Boston University, “Whether a state has a large-capacity ammunition magazine ban is the single best predictor of the mass shooting rates in that state.”²⁵ Petulla, “Here Is 1 Correlation between State Gun Laws and Mass Shootings.”

Conclusion

Assault weapons and high-capacity magazines help fuel gun violence in the United States. Research and evidence from mass shooting incidents in which four or more people are killed clearly show that assault weapons and high-capacity magazines are the weapon of choice for public mass shooters. Prohibiting access to assault weapons and limiting the capacity of ammunition magazines can reduce the number of people killed and wounded by shooters intent on inflicting mass casualties. 

In 2022, the US House of Representatives passed legislation to reinstate the federal prohibition on assault weapons and high-capacity magazines.²⁶HR 1808 (117th Congress, 2021–2022), https://www.congress.gov/bill/117th-congress/house-bill/1808. Despite the majority of adults in the United States supporting the law,²⁷Gallup, “Guns,” accessed December 23, 2022, https://news.gallup.com/poll/1645/guns.aspx. In June 2022, when asked, “Do you think there should or should not be a ban on the manufacture, possession, and sale of semiautomatic guns, known as assault rifles?” 55 percent of respondents said there should be. as of December 2022, the US Senate had not voted on the bill. In the absence of a federal law, state lawmakers can take action to save lives by passing laws to prohibit these dangerous weapons.