ORLANDO • The weapon used in a deadly shooting spree at a Florida high school was an AR-15 semi-automatic rifle, according to media reports.
The AR-15 is a lightweight, magazine-fed, gas-operated semi-automatic rifle. It is a semi-automatic version of the US military's M-16 rifle.
The gun is among the must-have weapons for American enthusiasts and figures heavily in popular culture, with the hashtag #ar15 used 1.7 million times on Instagram, with more users uploading images featuring the weapon by the minute.
The weapon, or variants of it, has been used in several mass shootings before the latest incident, including in Aurora, Colorado; Newtown, Connecticut; San Bernardino,California; Sutherland Springs, Texas; and Las Vegas, in which a total of 137 people were killed, reported NBC News.
It is the United States' most popular rifle, with one out of every five firearms purchased in the country an AR-style rifle, according to a National Shooting Sports Federation estimate. Americans own 15 million AR-15s, which range in price from about US$500 (S$656) to more than US$2,000.
One of the visceral reasons for the weapon's appeal is the speed at which projectiles leave the rifle, delivering a more devastating blow to bones and organs. Projectiles are also more likely to break apart upon impact, inflicting more damage.