On February 20, 2018, the Trump administration issued a presidential memorandum directing the Department of Justice to reinterpret federal firearms law in a way that effectively banned bump fire stocks. The memorandum instructed the DOJ to apply the existing statutory definition of "machinegun" under the National Firearms Act to aftermarket devices that artificially increase the firing rate of semi-automatic weapons. Rather than pursuing new legislation, the administration used executive authority to reclassify these devices as illegal automatic weapons, bypassing Congress entirely. The action set a compliance deadline of March 26, 2019, requiring Americans who possessed bump fire stocks to either destroy them or surrender them to law enforcement.

The practical effect was immediate and sweeping. Gun owners who had legally purchased bump fire stocks—devices that attach to semi-automatic rifles to mimic machine gun fire—suddenly faced federal criminal liability for possession. The memorandum impacted an unknown number of civilian owners, as bump stock sales data remained largely untracked, making the scope of affected individuals difficult to quantify. The action emerged directly in response to the Las Vegas shooting in October 2017, where a gunman using bump-equipped weapons killed 60 people, making it one of the deadliest mass shootings in American history.

This firearms reclassification represents a distinct departure from the Trump administration's broader civil rights trajectory. While subsequent actions—including the slowdown in Education Department discrimination complaints, investigations targeting transgender students, and restrictions on execution methods—generally narrowed civil rights protections, the bump stock reclassification appeared to constrain Second Amendment activity. The action demonstrated inconsistency in how the administration applied executive power across different policy domains, using regulatory reinterpretation as a tool when aligned with stated objectives.

The reclassification has withstood legal challenges. Courts have largely upheld the DOJ's reinterpretation, with the Supreme Court declining to hear challenges in 2019. Compliance occurred with minimal organized resistance compared to other Trump-era firearms regulations. The action remains active and in effect, creating an ongoing gap between pre-2018 owners and subsequent purchasers in terms of what devices are legally available.