“Hunting, recreational shooting and home defence” are just a few suggested uses of America’s most popular rifle, according to one of the AR-15’s manufacturers.
Yet many others see the lightweight, rapid-fire, military-style weapon – used to kill 12 people at a Navy Yard in Washington – in a more sinister light.
“It's the preferred mass shooter's weapon of choice,” says U.S. Staff Sergeant Alonzo Lunsford – himself a victim of a gun massacre.
Indeed, no fewer than seven rampages out of the 10 that have taken place in the U.S. over the last 14 months have involved AR-15s – and the gun was mostly lawfully purchased.
The gun’s legality was first questioned after James Holmes, 25, dressed as the Joker and used one to kill 12 cinemagoers at a Batman movie in Colorado on July 20, 2012.
Five months later, 22-year-year old Jacob Roberts stole an AR-15-style rifle from a friend, took to a mall in Clackamas, Oregon and opened fire on shoppers, killing two.
Three days later, on December 14, 2012, Adam Lanza, 20, used one kept at the home he shared with his mother to kill 26 children at the Sandy Hook Elementary School.
The murder sparked a massive row over gun control after President Barack Obama promised to use “whatever power this office holds” to introduce reforms.
Specifically, anti-gun advocates have argued for AR-15-style rifles to be banned – like they are in Britain.
Yet gun lobbies – and their supporters in the 47% of U.S. households with firearms - quickly stymied the proposals by pressuring congressmen to vote against limits.
Their arsenal of lawyers also argued that new controls would infringe Americans’ rights to bear arms under the Second Amendment to the Constitution.
So America has remained the most heavily armed place on earth - with 94 firearms per every hundred residents – and one of the highest gun crime rates in the world.
Most notably, shootings continued to be dominated by the AR-15. It's capable of firing 45 high-powered rounds a minute and evolved from the U.S. Army’s M16 automatic weapon into a semi-automatic civilian version.
On February 19, 2013 Syed Ali used one to kill four people during a rampage across three small California towns.
On May 22, Jonathan Shank opened fire at a police patrol in Longmont, Colorado with an AR-15 and was critically injured in the process.
A month later, on June 13, John Zawahri, 23, used one to murder five people in a killing spree in Santa Monica, California.
And right now Aaron Alexis is accused of using an AR-15 in the Navy Yard massacre.
The weapon’s use didn’t surprise Sergeant Lunsford, who was shot seven times by fellow soldier Nadal Malik Hasan in the Fort Hood massacre of 13 soldiers in 2009.
“Almost every mass shooting involves an AR-15 assault rifle,” he told CNN's Piers Morgan last night.
“But I don't see a logical reason why any civilian needs to have one of these killing machines.”
Supporting this view – and reflecting on owners’ motivations - British weapons expert Peter Donaldson said: “It’s basically the same as letting civilians carry Kalashnikovs.
“The only difference between the AR-15 and the M16 and M4 assault rifles used in armed forces around the world is that it is semi-automatic, rather than fully automatic.
“But this means it is still fires rounds at a rate of almost one per second.
“Another reason people might like the AR-15 is that it is highly accurate - to a range of around 300 metres in fact.
“But it is hard to see why such a deadly weapon would need to be used in anything other than a military context.”
However, part of the appeal of the gun is the military-grade features – including the ability to fire the same Nato 5.6mm bullets used by American troops.
Thanks to aircraft-grade aluminium, the gun, which weighs as little as 5.5lb, is almost 3lb lighter than the SA-80 used by British soldiers – yet every bit as deadly.
The AR-15, which was developed into a civilian version of the M16 by Colt in 1963, can also take enormous magazines of up to 100 bullets, although these are rare.
Most U.S. states only allow the sale of 30-round clips, but in the case of the cinema shooting Holmes got round Colorado law by purchasing the ammunition online.
The initial high cost of the weapon ensured only a relatively few were sold in the U.S. up until the 1980s.
But after other firms were given the right to produce slightly modified versions of the AR-15 – albeit under a different name – prices have dropped and sales have soared.
It is now possible to buy a basic version of the military-style weapon for under £400 in the US, which has become another key factor to their appeal.
Indeed, manufacturers such as Bushmaster, struggled to keep up with a huge surge in demand amid fears of a ban after the Sandy Hook massacre.
America’s deadly love affair with the AR-15 looks unlikely to end soon.