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)

The X-47B prototype on Tuesday flew off an aircraft carrier and into the history books. Today's achievement, the first-ever catapult launch of an unmanned aircraft from the flight deck of a carrier, promises to open up a new chapter in the annals of naval aviation. Photo: An X-47B pilot-less drone combat aircraft is launched for the first time off an aircraft carrier, the USS George H. W. Bush, in the Atlantic Ocean off the coast of Virginia, May 14, 2013. The U.S. Navy made aviation history on Tuesday by catapulting an unmanned jet off an aircraft carrier for the first time, testing a long-range, stealthy, bat-winged plane that represents a jump forward in drone technology. (Photo by Jason Reed/Reuters)

The Spirit of Ecstasy, also called “Emily”, “Silver Lady” or “Flying Lady,” was designed by English sculptor Charles Robinson Sykes and carries with her a story about a secret passion between John Walter Edward Douglas-Scott-Montagu (second Lord Montagu of Beaulieu after 1905, a pioneer of the automobile movement, and editor of The Car Illustrated magazine) and his love and the model for the emblem, his secretary Eleanor Velasco Thornton. Photo: Worker Ronald Little displays a finished “Spirit of Ecstasy”. (Photo by Stefan Wermuth/Reuters)

Men use ropes to try and right a supply truck overloaded with wheat straw along a road in Dargai, in the Malakand district, about 100 miles northwest of Pakistan's capital Islamabad, on April 13, 2012. (Photo by Mian Khursheed/Reuters)

Iraqis run for cover as they flee Mosul's Al-Tayaran neighbourhood on February 28, 2017, during an offensive by Iraqi forces to retake the area from Islamic State (IS) group fighters. Hundreds of civilians fled through the desert to escape fighting and privation in Mosul, joining thousands of others who left their homes as conditions worsen in the city's west. (Photo by Ahmad Al-Rubaye/AFP Photo)

A cosplayer uses moving stairs during the first public day of the world's largest computer games fair Gamescom in Cologne, Germany August 23, 2017. (Photo by Wolfgang Rattay/Reuters)

A participant in the Crazy Races extreme sports game competes in the cross-country obstacle race in Ufa, Russia on September 21, 2015. (Photo by TASS/Barcroft Media)

A truck laden with logs travels in Araribóia Indigenous Reserve, Maranhão, Brazil on August 7, 2015. Loggers have been stealing hardwood trees from indigenous lands in Brazil. The Guardians of the Forest are an armed militia formed by the Guajajara tribe to protect their reserve. (Photo by Bonnie Jo Mount/The Washington Post)