WASHINGTON _ An arsenal assembled by Stephen Paddock in his Las Vegas hotel room included at least one device called a "bump stock" that modifies a semiautomatic weapon to fire rapidly, almost like a machine gun.
Fully automatic rifles are tightly controlled by federal law, and owning one without the proper permits is a felony punishable by up to 10 years in jail. But the bump stocks, which allow a shooter to fire off up to 800 rounds per minute, have been repeatedly certified as legal by the Bureau of Alcohol, Tobacco, Firearms and Explosives.
Sen. Dianne Feinstein, D-Calif., included a ban on the devices in her failed 2013 bill to ban assault weapons, and she said Tuesday that it is time for Congress to act.
"I'm looking at how best to proceed with legislation to finally close this loophole," she said in a statement. "This is the least we should do in the wake of the deadliest mass shooting in U.S. history. It should be our highest priority."
Although Paddock had weapons modified with the bump stocks, authorities have not confirmed that he used those weapons in his rapid fire assault on a music festival crowd. The publicity of the shooting has apparently sparked a run on buyers trying to find them, as company websites crashed and sellers reported they were out of stock.
Under current law and its interpretation by ATFE, the devices are permitted. Manufacturers even put the approval letters from the agency on their websites to reassure prospective buyers.
"Did you know that you can do simulated full-auto firing and it is absolutely legal?" says one Texas manufacturer, Bump Fire Systems. The 2010 letter from the ATFE says the device was billed by the company as a way to assist people "whose hands have limited mobility" to rapidly fire an AR-15 military style rifle.
The bump stock, because it has "no automatically functioning mechanical parts" is a "firearm part and is not regulated" under gun control laws, the agency said in a June 2010 letter to the company.
Those decisions were made at an office of the ATFE called the Firearms Technology Branch at a facility in West Virginia. Richard Vasquez, former acting chief of that division, said the decision on the bump stocks was not that difficult or particularly controversial with the agency.
The reason is in the legal definition of a "machine gun" in federal law _ a gun that can fire more than one shot "by a single function of the trigger."
Semiautomatic weapons fire one shot per trigger pull. The bump stock devices work by allowing the gun's stock to slide back and forth, and use the gun's recoil as a way to dramatically accelerate the speed of the shots.
But in the ATFE's view, that doesn't make them machine guns, because technically the firing mechanism hasn't been changed, and the shooter is still squeezing off one shot per trigger pull.
"A lot of discussion was made over it, and there was a lot of thought put into it," said Vasquez, who retired from the government and now works as a consultant for the firearms industry.
"When when we looked at it ... we could not fit it into the definition" of a machine gun, he said.
"That's all a government agency can do, because Congress writes the laws," said Vasquez, who retired from the agency and now works as a consultant for the firearms industry.
