The attempted assassination of former US president Donald Trump with a semi-automatic rifle illustrates once again how easy it is for shooters in the US to get their hands on inexpensive, easy-to-use, military-style weapons.
The AR-15-style rifle is one of the most popular guns in the US. It has also been a common denominator in some of the country's worst mass shootings.
Here are some key facts about the weapon:
Why are AR-15s so lethal?
The AR-15 is a semi-automatic weapon, meaning a user can fire multiple shots in quick succession.
Its cousin, the M-16, has been used by the US military since Vietnam. While some military assault rifles are fully automatic, civilians are prohibited from owning such weapons in most circumstances.
AR-15s fire high-velocity bullets that travel at triple the speed of a handgun round, are accurate over long distances, and cause expansive, devastating wounds to soft tissue and internal organs.
While handguns account for more deaths per year in the United States, AR-15s have frequently been used in high-profile mass shootings.
In May 2022, a former student used an AR-15 to shoot dead nineteen children and two teachers at Robb Elementary School in Uvalde, Texas.
The weapon was also used in October 2017 in Las Vegas, where a gunman massacred 60 people at a music festival.
Cheap and easy
Buying an AR-15 is easy. Depending on the state of residence, a prospective owner can walk into a gun shop and, after presenting a valid ID, buy a rifle or shotgun provided they can pass a federal background check.
This process looks at a buyer's criminal history or whether they have ever been committed to a mental institution. But even this cursory check can be flouted in the case of private sales.
The National Rifle Association (NRA) touts the rifles for recreational target practice and home defense, but critics say their lethality means they do not belong in civilian hands.
Part of the reason for the popularity of AR-15s in America is that they are widely customizable, with owners able to add scopes, large-capacity magazines and a plethora of other accessories.
The Bureau of Alcohol, Tobacco, Firearms and Explosives does not know how many assault weapons there are in America -- they are prohibited by federal law from keeping a gun registry database.
A Washington Post poll in 2023 estimated that one in 20 American adults own at least one AR-15.
Banned in several states
Assault weapons were banned in 1994 under president Bill Clinton, but the restriction lapsed in 2004 amid pressure from the powerful NRA.
Federal efforts at reforms to gun laws have been stymied ever since, with critics arguing that they infringe the constitutional right to own a firearm, enshrined in the Second Amendment.
Several states, like California, Illinois, Maryland, New Jersey and Washington DC, have however banned ownership of assault weapons.
California claims its gun safety laws have helped save 19,000 lives in a decade.
In May, President Joe Biden's administration moved to crack down on firearm sales at gun shows and online that evade federal background checks.
But several Republican-led states quickly sued to block the measure.