Why the AR-15 rifle is the weapon used in so many US mass shootings

The National Rifle Association says the AR-15 is America’s most popular rifle, used safely by millions of people for sport, but it also has a dark reputation as the weapon used in dozens of mass killings.

Initial reports suggest it was the gun used in the attack on Wednesday at Stoneman Douglas High School in Florida.

And it was the weapon carried in some of the attacks whose names are burned into America’s memory: The Sandy Hook Elementary School in Newtown, Connecticut, San Bernardino and last year's shooting at a congressional baseball practice in Virginia.

Assault weapons were banned in the US in 1994, a measure that has since expired.

Since then advocates of gun control estimate their numbers have exploded to about eight million.  Of those the light, customisable, military-styled AR-15 is the most popular.

Although it has no fully-automatic mode, it is still marketed as coming from a lineage of military-grade arms.

It is modelled on the M-16 used by the US Army and Marine Corps, and carried by thousands of troops around the world. 

Even for people who have never served, it offers a sense of joining the war effort.

“It speaks to the fact that there are a lot of young men in the US who will never be in the military but feel that male compulsion to warriorhood,” Tom Diaz, the author of The Last Gun told The New York Times. “Owning an assault weapon is a passport to that.” 

Adam Lanza used a Bushmaster Ar-15 when he shot 20 children aged between six and seven years old, as well as six adult staff members, at Sandy Hook Elementary School in December 2012.

And Syed Rizwan Farook and Tashfeen Malik used two AR-15 variants when they killed 14 people in San Bernardino in December 2015 during their Isil-inspired attack.

This article was originally published in June 2017.