Once an obscure device, ‘bump stocks’ are in the spotlight

ATLANTA — The Las Vegas attacker possessed a littleknown device called a “bump stock” that was not widely sold — until now.

Originally created with the idea of making it easier for people with disabilities to shoot a gun, the attachments allow a semi-automatic rifle to mimic a fully automatic weapon by unleashing an entire large magazine in seconds. Now the deadliest mass shooting in modern U.S. history has drawn attention to the devices, which critics say flout federal restrictions on automatic guns.

The stocks have been around for less than a decade. The government gave its seal of approval to selling them in 2010 after concluding that they did not violate federal law.

The device basically replaces the gun’s shoulder rest, with a “support step” that covers the trigger opening. By holding the pistol grip with one hand and pushing the barrel with the other, the shooter’s finger comes in contact with the trigger. The recoil causes the gun to buck back and forth, “bumping” the trigger.

Technically, that means the finger is pulling the trigger for each round fired, keeping the weapon a legal semi-automatic. The rapid fire does not necessarily make the weapon any more lethal — much of that would be dependent on the type of ammunition used. But it does allow the person firing the weapon to get off more shots more quickly.

It’s unclear how many have been sold. The industry leader, Slide Force, did not return messages seeking comment. But the Abilene, Texas, company’s Facebook page is filled with videos extolling its features, including one in which a woman gushed, “It’s so easy because once you slid it forward and leaned into it, it just fires.” In another video, a man fires off 58 rounds to celebrate his 58th birthday in just 12 seconds.

Sales for firearms or specific accessories seem to jump after every high-profile shooting. That will likely happen again with bump stocks, said Garen Wintemute, director of the Violence Prevention Research Program at the University of California, Davis.

“People will go, ‘Oh geez, I should get one of those.’ The other is that people will be concerned about efforts to ban them,” Wintemute said.

Manufacturers tout the stocks, which typically sell for less than $200, as offering a simple and affordable alternative to automatic weapons without the hassle of a rigorous background check and other restrictions.

Attacker Stephen Paddock had 23 guns and two bump stocks in his Mandalay Resort room.