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)

Salespeople roll out a reproduction of the famous work “Girl with a Pearl Earring” at the artist village on June 11, 2014 in Shenzhen, China. The Dafen Artist Village in Guangdong province, China, is home to thousands of artists who reproduce some of the world's most iconic paintings as well as create their own works. The village, on the outskirts of Shenzhen, is becoming a major center for original Chinese art. (Photo by Palani Mohan/Getty images)

Cormorant masters and boatmen prepare sea cormorants for the nights “Ukai” on July 2, 2014 in Gifu, Japan. In this traditional fishing art “ukai”, a cormorant master called “usho” manages cormorants to capture ayu or sweetfish. The ushos of River Nagara have been the official staff of the Imperial Household Agency of Japan since 1890. Currently six imperial fishermen of Nagara River conduct special fishing to contribute to the Imperial family eight times a year, on top of daily fishing from mid-May to mid-October. (Photo by Chris McGrath/Getty Images)

Women in kimonos look at pictures they took in front of paper lanterns during the annual Mitama Festival at the Yasukuni Shrine in Tokyo July 13, 2014. Over 30,000 lanterns light up the precincts of the shrine, where more than 2.4 million war dead are enshrined, during the four-day festival. The festival goes on till July 16. (Photo by Yuya Shino/Reuters)

A journalist takes photographs at the site of Thursday's Malaysia Airlines Boeing 777 plane crash near the settlement of Grabovo, in the Donetsk region July 18, 2014. World leaders demanded an international investigation into the shooting down of Malaysia Airlines Flight MH17 with 298 people on board over eastern Ukraine, as Kiev and Moscow blamed each other for a tragedy that stoked tensions between Russia and the West. (Photo by Maxim Zmeyev/Reuters)

A meteor streaks over the sky during the Perseid meteor shower at the Maculje archaeological site near Novi Travnik August 12, 2014. According to NASA, the annual Perseid meteor shower reaches its peak on August 12 and 13 in Europe. The fireballs from the meteorites are fast and plentiful, although a nearly full moon (Supermoon) makes it difficult to view them this year, the agency adds. (Photo by Dado Ruvic/Reuters)

People fall down as they try to form a human pyramid to break the “Dahi handi”, an earthen pot filled with curd, an integral part of celebrations to mark Janmashtami in Mumbai, India, Monday, August 18, 2014. Hindu devotees take part in the celebration in which an earthen pot is suspended high above the ground and groups of young men and children form a human pyramid to reach the pot and break it. The festival celebrates the birth of Hindu god Lord Krishna, one of the most popular gods in Hinduism. (Photo by Rafiq Maqbool/AP Photo)

A badly-weathered composition doll, made from compressed wood chip, has its flakey paint cut off before being repaired and repainted by Gail Grainger, a 14-year veteran doll repairer at Sydney's Doll Hospital, August 19, 2014. Opened in 1913, Sydney's Doll Hospital has worked on millions of dolls, teddy bears and other toys. Behind a toy shop on a busy suburban street in Sydney's south, “doll surgeons” transplant fingers, toes and heads, and repair broken eye sockets in dolls who were the victim of a childhood tantrum or sibling rivalry, sometimes decades ago. (Photo by Jason Reed/Reuters)