A goofy little doodad

The molded piece of plastic or metal — a ‘bump stock,’ as it has become known to assault-rifle enthusiasts — harnesses a gun’s natural recoil, allowing it to bounce back and forth off a shooter’s trigger finger and unleash up to 100 rounds in seven seconds, according to an ad for one of the devices.

“It’s a goofy, little doodad,” said Rick Vasquez, the former firearms official who first signed off on a recommendation that the Bureau of Alcohol, Tobacco, Firearms and Explosives need not regulate the devices.

As Vasquez reasoned, the invention did not technically alter a gun’s trigger mechanism, as earlier attempts had, with springs, hydraulics or electric current. So it did not infringe on a law that bans the sale of machine guns manufactured after 1986 and restricts the sale of those made before then.

Police found 12 weapons with bump-fire stocks in the shooter’s hotel room. These devices can be used to make semi-automatic weapons perform like machine guns.

Functionally, however, weapons experts say, the increasingly popular bump stock has allowed even novice gun-owners to easily modify a legal semiautomatic rifle into one that resembles a battlefield machine gun.

“It’s for those guys who want to look like super ninja when they’re out on the range — they’re the people my peer group makes fun of,” Vasquez, a former Marine, said Wednesday, returning from a firearm instruction course he conducted in South Carolina. “If you want a machine gun, join the Marines.”

Federal law enforcement officials said that gunman Stephen Paddock fired weapons outfitted with bump stocks, a dozen of which were found in his hotel suite. Audio of the attack, experts said, makes clear that the shooter unleashed a torrent of bullets faster than he could have fired manually.

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The National Rifle Association declined to comment on the use of the devices in the Las Vegas attack, or on Feinstein’s proposed legislation. Two attorneys for the most prominent bump stock manufacturer, Slide Fire, which received the favorable 2010 ATF decision, also declined to comment.

The Slide Fire website on Wednesday said the device was out of stock “due to extreme high demands.”