House Speaker Paul D. Ryan backed away Wednesday from legislative action to ban "bump stocks," the device a mass shooter used in Las Vegas earlier this month to create machine-gun-like rapid fire from his legal semiautomatic rifle, killing 58.

Instead, Ryan and many of his fellow House Republicans hope the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) will act administratively to outlaw the devices, which the agency ruled legal in 2010.

"We think the regulatory fix is the smartest, quickest fix, and then, frankly, we'd like to know how it happened in the first place," Ryan (Wis.) told reporters Wednesday. He did not discuss pursuing legislation to address the issue.

[The ATF-approved ‘goofy little doodad’ used by Las Vegas gunman Stephen Paddock]

Ryan made his remarks a day after 20 bipartisan House members backed a bill to ban bump stocks and similar devices meant to accelerate the firing rate of semiautomatic rifles.

The bill, sponsored by Reps. Carlos Curbelo (R-Fla.) and Seth Moulton (D-Mass.), would make it illegal to manufacture, own or transfer any device that "is designed and functions to increase the rate of fire of a semiautomatic rifle but does not convert the semiautomatic rifle into a machinegun."

Fully automatic machine guns, which fire off multiple rounds with a single pull of the trigger, are much more tightly regulated than semiautomatic weapons under federal law, and it generally is illegal to own guns of that type manufactured after 1986. Bump stocks avoid those restrictions by utilizing a semiautomatic weapon's recoil to repeatedly engage the trigger.

Curbelo said Tuesday that administrative action alone would not solve the issue, noting that ATF has previously ruled that the devices should not be regulated like machine guns.

"If they were to get sued after changing that interpretation, the plaintiffs would have a very strong case, given the agency's previous determinations," he said. "So if people agree with banning these devices, let's pass a law. It's the best way to make sure it gets done."

Ryan's comments Wednesday went somewhat further than his comments last Thursday, shortly after the National Rifle Association issued a statement saying that bump stocks ought to be more tightly restricted and that ATF ought to revisit its prior rulings.

"Fully automatic weapons have been outlawed for many, many years," Ryan said last Thursday. "This seems to be a way of going around that, so obviously we need to look how we can tighten up the compliance with this law so that fully automatic weapons are banned."

Mary Markos, an ATF spokeswoman, said Wednesday that the agency is "not releasing anything at this time" regarding its regulation of bump stocks.

[Top gun-control advocate: GOP embrace of ‘bump stock’ restrictions is progress]

Although many gun-rights advocates in Congress have expressed a willingness to restrict bump stocks and similar devices, they are wary of taking action through legislation. With the presidency and both chambers of Congress under GOP control, and yet few pieces of major legislation signed into law, multiple House Republicans said privately this week that it would be politically untenable to put a gun-control bill on President Trump's desk.

"It's the height of irony if we don't repeal Obamacare, we don't cut taxes, but we do implement more gun control," said Rep. Thomas Massie (R-Ky.), chairman of the House Second Amendment Caucus. "That's a perversion of the GOP agenda, and I think my colleagues recognize that, which is why they're hoping the ATF will do it."

But there may be a critical mass of moderate Republicans that could help push a bump-stock bill to the fore. Curbelo said Tuesday that he expected to add "many more" Republican co-sponsors to his measure in the coming days.

A Washington Post count of GOP lawmakers suggests that enough Republicans are willing to join with Democrats in the House to pass a ban.

Gun-control advocates, meanwhile, also are pushing for legislation. Mark Kelly, the co-founder of Americans for Responsible Solutions, told reporters Friday that legislation is the most reliable way not only to restrict bump stocks but also deal with the ancillary issues any new restrictions might create.

"We don't want people to have automatic weapons that we don't know who they are, they're not registered. These people aren't fingerprinted. That is not a good scenario," he said. "We need to put these people in the position that the thing that they have, that they are now holding something that is illegal for them to be in possession of."

Read more at PowerPost