In recent weeks, the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) has begun cracking down hard on grey areas in firearm commerce.

The agency is doing so without President Joe Biden’s preferred nominee David Chipman at the helm and in the face of increasing complaints from gun-control groups.

The latest example is an open letter sent Thursday to all federally-licensed firearms dealers (FFLs) revealing the ATF has determined many forced-reset triggers (FRTs)—drop-in replacement triggers that increase the speed a semi-automatic gun can be fired—are considered machine guns under federal law. That will subject the previously-unregulated trigger devices to heavy regulation under the National Firearms Act (NFA).

“ATF’s examination found that some FRT devices allow a firearm to automatically expel more than one shot with a single, continuous pull of the trigger,” the letter reads. “For this reason, ATF has concluded that FRTs that function in this way are a combination of parts designed and intended for use in converting a weapon into a machinegun, and hence, ATF has classified these devices as a ‘machinegun’ as defined by the [National Firearms Act] and [Gun Control Act].”

Illegal possession of a machine gun carries a penalty of up to 10 years in federal prison. And it appears the agency is ready and willing to enforce those provisions.

“Based on ATF’s determination that the FRTs that function as described above are ‘machineguns’ under the NFA and GCA, ATF intends to take appropriate remedial action with respect to sellers and possessors of these devices,” the letter reads.

The letter explains those who have already acquired the devices legally should contact ATF to work out a way to relinquish them. For those that do not, the ATF may be paying them a visit in the future.

The veiled threat of future raids by federal agents over a niche firearms accessory calls into question recent attacks from gun-control organizations and The New York Times that the agency is too friendly to the industry. Major gun control groups Brady and Giffords have criticized the ATF’s work with the National Shooting Sports Foundation, the firearms industry’s trade group, and asked President Biden to direct the agency to sever ties with the group.

Similarly, a Times article from earlier this month describes acting ATF director Marvin Richardson as “an industry-friendly subordinate pumping the brakes” on federal gun control efforts. It also featured harsh criticism from John Feinblatt, President of Everytown for Gun Safety, calling for a “top-to-bottom overhaul” of the ATF.

“That starts with the administration making sure the agency has the resources and leadership it needs to regulate an industry that has consistently prioritized profits over public safety,” Feinblatt told the New York Times.

But if the agency lacks the resources and leadership necessary to regulate the gun industry, you wouldn’t know it based on its actions over the last several months.

Aside from Thursday’s open letter on FRTs, the ATF has also cracked down on home-built suppressors. On February 28, the agency denied 850 form 1 applications—the form that applicants who are not licensed to manufacture National Firearms Act (“NFA”) regulated items must use to create an NFA item legally. The applications were denied due to a change in interpretation by the agency of the definition of when parts constitute a silencer under law.

The agency has also, at least according to the NRA’s Institute for Legislative Action, started enforcing a new zero-tolerance policy this year on licensed gun dealers at the request of the Biden Administration. Under this new practice, FFLs can have their license revoked after a single violation of bookkeeping requirements or other regulations.

On top of the forthcoming rules to reclassify commonly owned pistol braces as NFA items and redefine “firearms” under federal law, these latest actions reveal a federal agency very much willing to regulate the firearms industry and gun owners more broadly. And they’re doing it all after Chipman’s nomination failed, despite critiques from gun-control advocates who said he was necessary for enforcement.