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)

Maj. Matt O'Donnell of Glenelg, MD shields himself from rotor wash as Ospreys carrying the delegation of U.S. Secretary of Defense Leon Panetta leaves on March 14, 2012 at Forward Operating Base Shukvani, Afghanistan. Panetta is also scheduled to meet with President Karzai during his two-day visit to Afghanistan. The trip comes as the Taliban has vowed revenge following this past weekend's killing spree by a U.S. soldier who is accused of killing 16 civilians in Afghanistan. Most of those killed were children and women. (Photo by Scott Olson/Getty Images)

People pose for photographs in the wind during Typhoon Saola in Tseung kwan O, in Hong Kong on Saturday, September 2, 2023. Typhoon Saola made landfall in southern China before dawn Saturday after nearly 900,000 people were moved to safety and most of Hong Kong and other parts of coastal southern China suspended business, transport and classes. (Photo by Billy H.C. Kwok/AP Photo)

Democratic presidential candidate and US Vice President Kamala Harris reacts as she holds a photographer's camera while flying on Marine Two, on her way to O'Hare International Airport, Chicago, Illinois, on August 20, 2024. Harris is traveling to Milwaukee, Wisconsin, to speak at a campaign event. (Photo by Kevin Lamarque/Pool via AFP Photo)

This April 9, 2016 photo provided by Bertrand Piccard via Global Newsroom shows Piccard taking a selfie on board Solar Impulse 2 during a test flight over the Pacific Ocean. The solar-powered airplane on an around-the-world journey had traveled 80 percent of the way from Hawaii to California by Saturday, April 23. The aircraft's destination on this leg of the journey is Mountain View, Calif., at the southern end of San Francisco Bay. (Photo by Bertrand Piccard/Global Newsroom via AP Photo)

“One talented photographer has managed to capture these jaw-dropping images that show off the beauty of the surf and the art hidden in the waves. Kenji Croman has a deep passion for bodyboarding and photography and was inspired to combine the two after growing up in Hawaii”. – Caters News. (Photo by Kenji Croman/Caters News)

Underwater photographer Sarah Lee uses a technique known as “duck diving” to capture these stunning photos of surfers in Hawaii. Surfers “duck dive” under the water to avoid incoming waves so they can get further out to sea. Photo: A surfer comes free from her surfboard. (Photo by Sarah Lee/Caters News)

A mural depicting Prime Minister Scott Morrison wearing an unbuttoned Hawaiian shirt, orange lei and Santa Claus hat while holding a cocktail by artist Scott Marsh is seen on a wall in Sydney, Wednesday, December 25, 2019. Morrison was under pressure since taking a much criticized family vacation to Hawaii during the wildfire crisis.(Photo by Steven Saphore/AAP Images via AP Photo)