PHILADELPHIA (CBS) — The FBI told CBS News the AR-style rifle used by the shooter in the attempted assassination of former President Donald Trump was legally purchased by and registered to the shooter’s father.  

Gun legislation is both complex and controversial and the laws change from state to state. Assault rifles, like the one used to shoot Trump, are banned in nine states, including New Jersey and Delaware.

“This is just a fact here in Pennsylvania, and in many states, those rifles are legal to buy,” Josh Fleitman, the campaign director with CeaseFire PA, said. “They were federally banned for 10 years, and once that ban was allowed to expire, we saw the rate of mass shootings triple.”

CeaseFire PA is a nonprofit, non-partisan gun violence prevention organization. The group has long been calling for the state to close a background check loophole for long guns including automatic rifles. Currently, Pennsylvania requires background checks for all handgun sales. It also requires background checks for long guns like assault rifles purchased from a firearm dealer but not those purchased from a private seller.

“Maybe it’s your next-door neighbor, maybe it’s the stranger in the parking lot outside of a gun show — if you’re buying an AR-15 or long gun from them, there’s no background check required,” Fleitman said.

AR-style rifles have been the focus of debate for the last two decades because it’s a weapon commonly used by mass shooters. The sheer velocity at which the bullet exits the gun is much more catastrophic to the human body compared to a handgun.

The Giffords Law Center tracks the correlation between gun laws and gun violence across the United States and gives states a grade on their prevention efforts. The group gives New Jersey an A, Delaware a B+ and Pennsylvania a B, recommending Pennsylvania close the background check loophole, pass a red flag law that prevents a person who might be dangerous or in crisis from having a gun, and enact a safe storage law.