At least half of U.S. states now outlaw devices that convert pistols into machine guns / Half of US states outlaw devices that turn pistols into machine guns / PTI protesters are equipped with machine guns, says CM Maryam / 3D printers turn handguns into machine guns for as little as 40 cents / Yemen weapons dealers selling machine-guns on X / The Supreme Court just effectively legalized machine guns / Homemade machine guns return US to the era of Al Capone and the Tommy gun / A surge of illegal homemade machine guns has helped fuel gun violence in the US / A surge of illegal homemade machine guns has helped fuel gun violence in the U.S.