The Bureau of Alcohol, Tobacco, Firearms, and Explosives has signaled to Congress that it would prefer new legislation instead of new regulation to impose restrictions on "bump stocks," which could end up being a major hurdle to any federal action on the firearms accessory.

Bump stocks were found at the site of the Las Vegas shooting. The accessory can essentially turn a semi-automatic weapon into an automatic weapon by using the recoil action of the gun to speed up the rate of fire.

In the wake of the shooting, Republicans and Democrats called for restrictions on the device, and the National Rifle Association suggested that the ATF find a way to issue a new regulation prohibiting the device.

But House aides said the ATF indicated at a lawmaker briefing last week that it's not ready to regulate bump stocks and promoted the idea of bump stock legislation.

"ATF is pushing for a legislative approach rather than going through an administrative process," a House aide told the Washington Examiner.

This aide said that during the meeting, the ATF didn't clarify whether they could re-regulate bump stocks, but did raise the option of new legislation.

Another House aide agreed that ATF's presentation made it clear that the agency is unlikely to push for a new regulation. This aide said the feeling at the agency is that current law is clear enough, and that it would be difficult to impose a new regulation limiting access to bump stocks in a way that's consistent with U.S. law.

The ATF told the Washington Examiner that it doesn't comment on "potential internal deliberations."

But the read from congressional aides appears to raise major questions about what lawmakers will do about bump stocks, if anything, if the ATF is unable or unwilling to issue a new rule.

New legislation seems highly unlikely in a Republican-led Congress, which may explain why Republicans including Speaker Paul Ryan, R-Wis., seemed much more open to a regulation.

"We think the regulatory fix is the smartest, quickest fix," Ryan said last week.

"What happened on the regulatory side," he added. "It makes sense that this is a regulation that probably shouldn't have happened in the first place."

Several Republican senators wrote the ATF on Oct. 6 to ask that it review the status of bump stocks.

The National Rifle Association has also said it prefers a regulatory review at the ATF, but didn't respond with a comment when asked Wednesday about the ATF's position.

"It is illegal to convert a semi-automatic to fully automatic," NRA Executive Director Chris Cox said this month. "The ATF needs to do their job, review these and if there is [a need for] further regulation, then we will work on further regulation."

The ATF may have run into a problem predicted by Rep. Thomas Massie, R-Ky., who leads the Congressional Second Amendment Caucus. Massie told the Washington Examiner this month that under current law, automatic weapons are those that discharge more than one round with a single pull of the trigger.

Bump stocks, he said, speed up the rate of fire, but still require the shooter to pull the trigger once for each round that is discharged. Massie said for that reason, there is no basis under the law to regulate bump stocks.

He also said it's unlikely that the ATF would go further to regulate bump stocks in the Trump administration, given that it had the chance to do so under the Obama administration, and didn't.

Massie split with the NRA on what to do about bump stocks, and said more time should be taken to investigate the Las Vegas shooting before any step is taken, whether it's a new rule or a new bill.