A large variety of weapons were for sale at the Washington County Fairgrounds Gun Show that drew thousands of people over the weekend, on March 22, 2013. (Photo by Gary Porter)

A member of Libyan forces allied with the U.N.-backed government fires a weapon on a pickup truck during a battle with Islamic State militants in Giza Bahreya, in Sirte, Libya October 27, 2016. (Photo by Hani Amara/Reuters)

Israeli soldiers from the mixed-gender Lions of the Jordan battalion, under the Kfir Brigade, check their weapons at the end of the last training before being assigned their posting, on February 28, 2017, near the West Bank village of Bardale, east of Jenin. (Photo by Jack Guez/AFP Photo)

A tattoo of a weapon covers the arm of a female inmate waiting to compete in the annual beauty contest at Talavera Bruce penitentiary in Rio de Janeiro, Brazil, early Thursday, November 23, 2017. Jail authorities say they organize the annual contest to encourage self-esteem, fight idleness and promote integration among women prisoners. (Photo by Silvia Izquierdo/AP Photo)

A boy shoots a World War II machine gun armed with blanks at an weapon exhibition during a military show near Kirovsk, about 30 kilometers (19 miles) east of St. Petersburg, Russia, Sunday, January 21, 2018. (Photo by Dmitri Lovetsky/AP Photo)

Vehicles and weapons of the Justice and Equality Movement (JEM) rebels are seen on display, after victory celebrations by the Sudanese Armed Forces (SAF) and the Rapid Support Forces (RSF), in Niyala Capital of South Darfur, May 4, 2015. (Photo by Reuters/Stringer)

A student from the General Yermolov Cadet School takes part in weapons training during a two-day field exercise near the village of Sengileyevskoye, just outside the south Russian city of Stavropol April 13, 2014. The General Yermolov Cadet School in the southern Russian city of Stavropol is a state-run institution that teaches military and patriotic classes in addition to a normal syllabus. (Photo by Eduard Korniyenko/Reuters)

John Klatt and the Air National Guard MXS (right) and Mike Wiskus and the Lucas Oil Pitts take to the skies at the Memphis Airshow, on Sat., September 26, 2016 in Millington, Tenn. (Photo by Brandon Dill/Invision for John Klatt Airshows, Inc./AP Images)