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)

Migrant Haya from Artoz, Syria, shows a picture of her town as she waits to cross the Slovenia-Austria border in Sentilj, Slovenia October 25, 2015. (Photo by Srdjan Zivulovic/Reuters)

Dhruva Aliman does a back somersault as he dismounts from a slackline on the beach at Santa Monica, California on October 19, 2014. Slackline is a balance sport where a line of webbing is adjusted at different levels of tension between two anchor points and participants (called slackers) perform tricks and stunts including somersaults. (Photo by Mark Ralston/AFP Photo)

Samy Rose Moshiri, an Iranian American artist and activist, covers the mouth of Belarusian activist Yadviga Krasovskaya after dousing themselves in fake blood on stage at a Freedom Rally for Iran, in support of Iranian women and against the death of Mahsa (Zhina) Amini, outside City Hall in Los Angeles, California, U.S., October 1, 2022. (Photo by Bing Guan/Reuters)

Nepal's indigenous women in traditional attire gather to participate in a rally to mark the International Day of the World's Indigenous People in Kathmandu, Nepal, Friday, August 9, 2024. (Photo by Niranjan Shrestha/AP Photo)

Participants costumed as zombies try to catch hobby runners during the so-called Zombie-Run at the harness racing track Karlshorst in Berlin, Germany, 18 May 2014. The runners carry small flags in their belts which they have to get safely across the finishing line while the zombies try to steal them. The sporting event is based on the US television series “The Walking Dead”. (Photo by Soeren Stache/DPA)

A sacrificial camel gets a haircut with patterns at the animal market on the outskirts of Karachi, Pakistan September 22, 2015. Muslims across the world are preparing to celebrate the annual festival of Eid al-Adha or the Feast of the Sacrifice, which marks the end of the annual haj pilgrimage, by slaughtering goats, sheep, cows and camels in commemoration of the Prophet Abraham's readiness to sacrifice his son to show obedience to Allah. Eid al-Adha in India falls on September 25. (Photo by Akhtar Soomro/Reuters)

Models blow kisses backstage at the Red Beard show during MBFWI presented by American Express Fall/Winter 2014 on March 13, 2014 in Istanbul, Turkey. (Photo by S. Alemdar/Getty Images for IMG)