Two weeks ago, bump stocks were just an odd-sounding firearm attachment largely unknown outside gun enthusiast circles.
That all changed early last week with the deadly shooting in Las Vegas, where police discovered a dozen of the devices in the shooter's hotel room overlooking the city's neon-lit Strip. Now, Republicans and Democrats in Congress, the National Rifle Association and other pro-gun groups are asking for a fresh look at the legality of bump stocks.
"We think the regulatory fix is the smartest, quickest fix," House Speaker Paul Ryan, R-Wis., said Wednesday during his weekly news conference. "We are still trying to assess why ATF let this go through in the first place."
The ATF is the Bureau of Alcohol, Tobacco, Firearms and Explosives, which is responsible for making a classification decision on firearms, their parts and accessories. The ATF declined to comment on any pending or potential future review of bump stocks.
But the ATF did finish a classification review of a bump stock, also known as a slide fire, in January 2010. It concluded that the device was a firearm part, not a machine gun, and therefore it was not regulated under the Gun Control Act or the National Firearms Act.
Machine guns, which are fully automatic, are strictly controlled in the United States. It is illegal for a private citizen to own a machine gun manufactured after 1986, although one can own, sell or purchase an automatic weapon made before that date.
Under U.S. law, a machine gun is defined as "any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger."
It is that last phrase — "by a single function of the trigger" — that is key to understanding ATF decisions, said Rick Vasquez, a firearm consultant and former acting chief of the ATF's firearms technology branch, which conducts classification reviews.
If a gun fires more than one bullet with a single pull of the trigger, then by law it is considered a machine gun. If, however, a gun fires only one bullet for each pull of the trigger, it is not.
Bump stocks, Vasquez said, enable an accelerated shooting rate, but the way they are designed ensures that each pull of the trigger only unleashes one bullet. That means, he said, that they don't qualify as machine guns under current law.
And while the NRA and some lawmakers are calling on the ATF to review the classification of bump stocks, former ATF officials and gun control advocates say that's a difficult hill to climb for several reasons.
For one, the bureau's hands are tied by current law, said Kristen Rand, the legislative director of the Violence Policy Center, which advocates for gun control.
"The ATF can't do anything about bump stocks without a change to the statute," she said. "Basically, all they can determine is whether or not a device causes a gun to fire in fully automatic mode, and it's banned, or it does not, in which case it can't be regulated."
But the law hasn't changed since the ATF originally signed off on bump stocks, so a regulatory change would require the bureau to reverse its original decision on the devices without Congress writing a new law or changing the controlling laws.
"If I looked at it again, looked at the same documents that we had at that time, then my opinion wouldn't change," Vasquez said.
David Chipman, a 25-year special agent with ATF who now serves as a senior policy adviser at the gun control group Americans for Responsible Solutions, agreed.
"If you ask me today if bump stocks meet the definition of full automatic, I would say no," Chipman said. "The trigger is functioning, so that's why my sense is that throwing it back to ATF can't possibly be the solution."
ATF could, in theory, change its mind under political pressure, Chipman said, but that would open it up to legal challenges from bump stock owners and manufacturers.
"If ATF just summarily chooses to make someone's product highly regulated after saying that it's not, it's likely to go to court," he said. "The only fix I think that would be quick would be for legislators to pass a new law."
There has been movement on Capitol Hill, where some lawmakers are pushing for a change to the law.
In the Senate, California Democrat Dianne Feinstein has proposed a bill that would make it illegal to buy, sell, manufacture or possess a device or accessory that is designed to accelerate the rate of fire of a semi-automatic rifle. That would cover bump stocks.
On the House side, Florida Republican Carlos Curbelo has proposed a similar bill.
Curbelo told NPR last week that the response from House Republicans to his proposal has been "overwhelming."
"I'm very confident that today a majority of Republicans in the House would support banning these devices," he said.
While lawmakers on both sides of the aisle have expressed support for the idea of banning bump stocks, it's unclear whether these efforts will maintain enough momentum to get passed into law.
STEVE INSKEEP, HOST:
House Speaker Paul Ryan says he favors regulations against bump stocks - you know, those attachments to semiautomatic rifles that makes them fire at the rate of a machine gun. Speaker Ryan says he favors restrictions after bump stocks were apparently used in the Las Vegas shooting. But he would rather the House not vote on them.
(SOUNDBITE OF ARCHIVED RECORDING)
PAUL RYAN: We think the regulatory fix is the smartest, quickest fix. And I'd frankly like to know how it happened in the first place.
INSKEEP: A regulatory fix, meaning he hopes authorities reinterpret existing law taking this out of Congress hands. NPR's Ryan Lucas is in the studio with us to talk through the law. Good morning.
RYAN LUCAS, BYLINE: Good morning.
INSKEEP: So Ryan asks the question, how are these things legal when machine guns are supposed to be tightly restricted? How are they legal?
LUCAS: Well, first let's step back and talk about what bump stocks are. So they are an attachment to a weapon that allows a semiautomatic to shoot at a faster rate - so something that would approach the rate of an automatic weapon or machine gun.
INSKEEP: This is what people heard on the video of the Las Vegas shooting, those bursts of fire.
LUCAS: Exactly. Exactly. And so the Bureau of Alcohol, Tobacco, Firearms and Explosives, which is commonly referred to as the ATF...
LUCAS: ...Is responsible for doing classification reviews, deciding how a weapon fits or an attachment fits into the spectrum of firearms. Now, we know that ATF did what's called a classification review about eight years ago on bump stocks. And I spoke with a number of former ATF officials who worked on this. And in trying to determine whether a firearm or a device is legal, the key question is how many bullets it shoots with one pull of the trigger. So if you pull the trigger once and you get one bullet, it's legal. It's a semiautomatic.
LUCAS: If you pull the trigger once and get a continuous stream of bullets until you let go of the trigger, it's a machine gun. And that is tightly regulated.
INSKEEP: OK. So they decided that the bump stock did not make something a machine gun effectively?
LUCAS: Basically, what happens is when you pull - each pull of the trigger with a bump stock...
LUCAS: ...Let's one bullet.
INSKEEP: ...It's a vibration that's making the trigger just be pulled many times very quickly...
INSKEEP: ...And so technically, it was OK. So they said it's legal. Can they actually revisit it and decide it's illegal after all?
LUCAS: They can. Now, ATF won't comment on whether they're doing that. They say it's internal deliberations, not something we talk about. But again, the former ATF officials that I've spoken with said that there's no reason that the bureau can't take another look at them. But remember, they've looked at the law before. They've looked to bump stocks before, and they said that they're good to go. So I spoke with a former official by the name of Rick Vasquez. He's a firearms consultant now, but he used to work as an ATF expert in the branch that reviews guns and gun accessories. And here's what he told me.
RICK VASQUEZ: If I looked at it again and looked at the same documents that we had at that time, then my opinion wouldn't change.
INSKEEP: Well, this raises a question. We found this out on issue after issue. There are many things President Trump would like to change about environmental law or about Obamacare. And it turns out that when there's a record of bureaucrats deciding that the law means one thing, it's very hard. It's a very long process to change it to mean something else. Is it really practical to just change the regulation?
LUCAS: Well, there's a question of whether it's practical, then there's a question of whether it's possible. So if ATF has done this before and said, well, it's legal - for it to reverse itself, to reverse the classification of bump stocks and say that they're now illegal under current law - that would likely face, you know, challenges in court.
INSKEEP: Does that mean that it would be better if Congress did try to change the law?
LUCAS: Well, there are efforts to do that. Senator Feinstein from California is pushing a bill that would ban anything like a bump stock, anything that would essentially accelerate the rate of fire a weapon. On the House side, Republican Carlos Curbelo has proposed a similar bill. And the experts that I've spoken to have certainly said that changing the law would be the most effective way of getting this off the street.
INSKEEP: Well, we'll see what happens. NPR's Ryan Lucas covers the Justice Department. Thanks very much.
LUCAS: Thank you. Transcript provided by NPR, Copyright NPR.