More mass shooters are using semi-automatic rifles – often bought legally

As the gunman fled down an alley after the deadly mass shooting at a July Fourth parade in suburban Chicago, an object fell from his black bag. It was a high-powered Smith & Wesson M&P 15 semi-automatic rifle, Illinois prosecutors said Wednesday in Lake County court.

Investigators found three 30-round magazines and 83 shell casings on the rooftop where police said the suspect shot at a crowd in Highland Park, killing seven and injuring dozens.

AR-15-style semi-automatic rifles or similar guns were used in at least six of the 14 mass shootings this year in which four or more victims died, according to the Gun Violence Archive. In eight of those shootings, information was unavailable about the types of guns used.

Although semi-automatic rifles have become more widely used over the past decade, handguns remain the most common type of weapon used in mass shootings, experts told USA TODAY. 

Most guns used in mass shootings – including those owned by the Highland Park suspect – were legally obtained, according to the Violence Project’s database.

Semi-automatic rifles becoming weapon of choice

Handguns have overwhelmingly been the weapon used by perpetrators since the Rockefeller Institute of Government’s Regional Gun Violence Research Consortium began tracking mass shootings within the past 50 or so years.

The consortium considers mass shootings any event in which targeted violence is carried out by one or more shooters in a public place, and multiple victims – including injuries and fatalities – are chosen at random or for symbolic value.

Over the past five decades, handguns were typically used 3-to-1 in mass shootings, said Jaclyn Schildkraut, interim executive director of the consortium.

According to the Violence Project, 78% of mass shooters used at least one handgun since 1966. The group keeps its own database and defines mass shootings as events in which four or more victims were killed, not including the shooter.

Experts from both groups noticed a shift.

“Over the last decade or so, we have seen an increase in the use of semi-automatic rifles,” Schildkraut told USA TODAY.

At least one rifle was used in about 44% of mass public shootings since the movie theater massacre in July 2012 in Aurora, Colorado; across the previous five decades, a rifle was used in almost 21% of mass shootings, said James Densley, co-founder and president of the Violence Project.

This year, mass shooters used semi-automatic weapons to kill more than 40 people from May and July in Buffalo, New York; Uvalde, Texas; Tulsa, Oklahoma; and Highland Park, Illinois.

HIGHLAND PARK VICTIMS: Loved ones will gather Friday in first funeral services after shooting

BUFFALO SHOOTING: DOJ urged to make expedited death penalty decision for  suspect

What's behind the rise of semi-automatic weapons?

Semi-automatic weapons are cheaper, more available and more aggressively marketed since the 10-year Federal Assault Weapons Ban expired in 2004, Densley told USA TODAY. The weapons’ lethal efficiency and easy reloading might appeal to mass shooters, he said.

Louis Klarevas, a research professor at Columbia University’s Teachers College, said the potential for a high death toll may play a factor for shooters but it’s hard to say with certainty.

“In the past 10 years, mass public shootings involving assault weapons have resulted in average death tolls that are more than double the average death tolls for mass public shootings that did not involve (them),” said Klarevas, who works with Columbia’s Scientific Union for the Reduction of Gun Violence.

People gather near a memorial at Tops Friendly Markets in Buffalo, N.Y., for the people killed on May 14 in a racially motivated shooting.
People gather near a memorial at Tops Friendly Markets in Buffalo, N.Y., for the people killed on May 14 in a racially motivated shooting.

What is a semi-automatic rifle?

The “AR” in AR-15, a semi-automatic weapon type commonly used in mass shootings, means ArmaLite, not “assault rifle.” The gun manufacturer created the gun for military use in the 1950s, then sold the model to Colt, according to NPR.

Semi-automatic rifles fire a single bullet at every pull of the trigger and automatically advance the next round to be fired. The magazines of AR-style rifles generally hold 10 to 30 rounds but can be fitted with specialized magazines that store extra ammunition.

The Violence Project reported that when semi-automatic weapons were used, nine people died on average and 11 were injured compared with six people who died and five who were injured when other types of guns were used.

Are mass shooters buying guns legally? 

Nearly half of mass shooters legally obtained the guns that law enforcement knew about through a licensed dealer, an unregulated private sale or other legal means, according to the Violence Project.

In four mass shootings from May to July, Gun Violence Archive data showed guns were bought legally:

  • In Buffalo, New York: The suspect bought his Bushmaster XM-15 semi-automatic rifle legally in upstate New York two months before a shooting at a supermarket May 14.

  • In Uvalde, Texas: The suspect legally bought two AR-style rifles and ammunition shortly after his 18th birthday and days before killing 21 people May 24 at Robb Elementary School.

  • In Tulsa, Oklahoma: The man accused of killing four people at the St. Francis Health System campus on June 1 legally purchased an AR-15-style rifle hours before the attack.

  • In Highland Park, Illinois: The suspect legally bought guns – including the one used July 4 – in 2020 and 2021.

In the 14 mass shootings in 2022, it's unclear how seven of the suspects obtained the guns, according to the Gun Violence Archive.

Densley, of the Violence Project, said that of the guns with known origins, data shows:

  • 65% of the 304 guns used from 1966 through May 2022 were legally obtained.

  • Of those, federal firearm dealers sold 127 guns, 12 came from private sales and 60 from legal, yet unknown, sources.

  • About 50% of the shooters used at least one weapon they legally purchased themselves.

The Violence Project does not know the origin of 22% of the 388 total guns used in this time period.

UVALDE SHOOTING: One month later, moments of silence, yet so much left to say

1 in 3 mass shooters were prohibited from owning a gun

Illegally obtained mass shooting weapons accounted for 27% of the Violence Project’s data, which showed 105 weapons were from either straw purchases, lying and buying, street sales, system failures or other means, Densley said.

Everytown for Gun Safety found 1 in 3 mass shootings from 2009 to 2022 involved a shooter that was legally prohibited from having a gun.

The organization, which considers four gun-related fatalities excluding the shooter to be a mass shooting, pointed to a lack of a comprehensive, federally required background checks, making way for easier gun purchases from unlicensed sellers in 29 states.

This article originally appeared on USA TODAY: Most mass shooters get their semi-automatic rifles, handguns legally