An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

Adrienne Sipe (L) and Brooke Gilliam of Washington D.C. leap off a snow podium they made near the U.S. Capitol in Washington February 13, 2014. A deadly and intensifying winter storm packing heavy snow, sleet and rain pelted a huge swath of the U.S. East Coast on Thursday, grounding flights and shuttering schools and government offices. (Photo by Kevin Lamarque/Reuters)

The solar eclipse is seen above the Washington Monument on April 08, 2024 in Washington, DC. People have traveled to areas across North America that are in the “path of totality” in order to experience the eclipse today. The next total solar eclipse that can be seen from a large part of North America won't happen until 2044. (Photo by Chip Somodevilla/Getty Images)

Reflected in an ornament, a reporter takes a photo of the White House Christmas Tree in the Blue Room during a media preview of the holiday decor at the White House in Washington, U.S., November 29, 2016. (Photo by Kevin Lamarque/Reuters)

A guest arrives outside the Anna Sui show at the Strand Rare Book Room in New York on February 10, 2024. (Photo by Jeenah Moon for The Washington Post)

Muslims gather to perform an Eid al-Fitr prayer, marking the end of the fasting month of Ramadan at Washington Square Park on Wednesday, April 10, 2024, in New York. (Photo by Andres Kudacki/AP Photo)

Natasha Cloud #0 and Diana Taurasi #3 of the Phoenix Mercury gather their team before the game against the Seattle Storm at Climate Pledge Arena on June 04, 2024 in Seattle, Washington. (Photo by Steph Chambers/Getty Images)

An attendee wears a MAGA necklace and shirt bearing the likeness of former president Donald Trump on the third night of the Republican National Convention on Wednesday, July 17, 2024 in Milwaukee. (Photo by Joshua Lott/The Washington Post)