WASHINGTON — The National Rifle Association is opposing a ban on “bump stocks” like the device used by the Las Vegas gunman to turn semi-automatic weapons into rapid-fire guns, stressing its support for more limited regulations.

The powerful lobby last week surprised many gun control advocates by embracing possible restrictions on the bump stock devices in the wake of the shootings that killed more than 50 people and injured 500, prompting bipartisan support in Congress for regulating or banning bump stocks.

But on Sunday, the NRA drew a line on an outright ban.

Chris Cox, the NRA’s chief lobbyist, said too much public focus was being placed on limiting the devices rather than preventing bad human behavior. He said it was the responsibility of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives — not Congress — to regulate the sale of bump stocks.

“We don’t believe that bans have ever worked on anything. What we have said has been very clear — that if something transfers a semiautomatic to function like a fully automatic, then it ought to be regulated differently,” Cox said.

It was a sign of a possible rocky road ahead for action by Congress.

Seeking momentum for gun restrictions, Sen. Dianne Feinstein on Sunday said only broader legislation would be effective in outlawing bump stock devices.

“Regulations aren’t going to do it. We need a law. It can’t be changed by another president,” said Feinstein, D-Calif., a longtime advocate of stricter gun control measures. She lamented the stratified lines of debate in “a gun-happy country.”

The debate over how to regulate bump stocks comes in the aftermath of the shooting at a Las Vegas music festival last week, America’s deadliest in modern history. While senior congressional Republicans and the Trump administration have expressed openness in restricting the gun accessories, lawmakers are divided over whether to rely on legislation or push for an executive branch order.

Marcio Jose Sanchez, The Associated Press Part of Reno Ave. near South Las Vegas Blvd is blocked with police tape in the aftermath of a mass shooting Wednesday, Oct. 4, 2017, in Las Vegas. A gunman opened fire on an outdoor music concert on Sunday. It was the deadliest mass shooting in modern U.S. history, with dozens killed and hundreds injured, some by gunfire, some during the chaotic escape.

Gregory Bull, The Associated Press An investigator works in the room at the Mandalay Bay Resort and Casino where a gunman opened fire from on a music festival Wednesday, Oct. 4, 2017, in Las Vegas. The gunman killed dozens and injuring hundreds at the festival.

This undated photo provided by Eric Paddock shows his brother, Las Vegas gunman Stephen Paddock. On Sunday, Oct. 1, 2017, Stephen Paddock opened fire on the Route 91 Harvest Festival killing dozens and wounding hundreds.



Marcio Jose Sanchez, The Associated Press A man pauses at a memorial for the victims of a mass shooting in Las Vegas, Wednesday, Oct. 4, 2017, in Las Vegas. Stephen Paddock opened fire on an outdoor music concert on Sunday killing dozens and injuring hundreds.

John Locher, The Associated Press People pause at a memorial for the victims of a mass shooting in Las Vegas, Wednesday, Oct. 4, 2017, in Las Vegas. A gunman opened fire on an outdoor music concert on Sunday killing dozens and injuring hundreds.

Marcio Jose Sanchez, The Associated Press Allison Easterbrooks pauses at a memorial for the people killed in Sunday's mass shooting on Wednesday, Oct. 4, 2017, in Las Vegas. Stephen Paddock opened fire on an outdoor music concert on Sunday killing dozens and injuring hundreds.



Gregory Bull, The Associated Press Agents from the FBI continue to process evidence at the scene of a mass shooting on Wednesday, Oct. 4, 2017, in Las Vegas. Stephen Paddock opened fire on an outdoor music concert on Sunday killing dozens and injuring hundreds.

John Locher, The Associated Press People pause at a memorial for the victims of a mass shooting in Las Vegas, Wednesday, Oct. 4, 2017, in Las Vegas. A gunman opened fire on an outdoor music concert on Sunday killing dozens and injuring hundreds.

Bump stocks are accessories that substitute for the regular stock and grip of a semi-automatic rifle and allow the weapon to fire continuously, some 400 to 800 rounds in a single minute. Bump stocks were found among the weapons used by sniper suspect Stephen Paddock and explain why victims in Las Vegas heard what sounded like automatic-weapons fire.

The bump stock device, which retails for around $200, causes the gun to buck back and forth, repeatedly “bumping” the trigger against the shooter’s finger.

Technically, that means the finger is pulling the trigger for each round fired, keeping the weapon a legal semi-automatic. Because it creates a significant rocking motion it also means that the gun is “spraying” bullets and it’s difficult to hit a target.

Adding to the uncertainty over the devices, the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives said last week it was in no position to re-examine its 2010 judgment that bump stocks were legal and that Congress would have to act.

“We think ATF ought to do its job, look at this, and draw a bright line,” said Wayne LaPierre, CEO of the National Rifle Association. He said the group has been clear in supporting current law that bans fully automatic firearms and is concerned that action by Congress could “fuzz the line” such as by imposing new restrictions on semi-automatic weapons.

Feinstein said her legislation banning bump stocks had attracted “Republican interest” although the 38 co-sponsors so far were all Democrats. The No. 2

WATCH: @SenFeinstein discusses the latest gun control debate in Congress on #MTP pic.twitter.com/ItT331gWKD — Meet the Press (@MeetThePress) October 8, 2017

Senate Republican, John Cornyn of Texas, has said he’s open to legislation and that he’d spoken with Judiciary Committee Chuck Grassley, who was interested in holding a hearing.

Sen. Ron Johnson, R-Wis., who heads the Homeland Security and Governmental Affairs committee, said Sunday he would be willing to support bump stock restrictions either by fiat or by a new law. “However that gets fixed, I’ll support it,” he said.

Seeking broader consensus, Sen. Chris Murphy, D-Conn., said that if Republicans were willing to pass a bill banning bump stock devices — like those used by the Las Vegas hotel sniper — he would support the legislation, even if it was not accompanied by any other restrictions of weapons purchases.

Murphy, an ardent supporter of gun control after the 2012 mass shooting at an elementary school in Newtown, Connecticut, said he would be willing to hold off for his broader goal, the institution of background checks for weapons buyers, if the Senate agrees on a narrower bump stock ban.

Feinstein spoke on NBC’s “Meet the Press” and CBS’ “Face the Nation,” LaPierre also was on CBS, Cox appeared on “Fox News Sunday” and Murphy and Johnson were on CNN’s “State of the Union.”