Supporters of the District gun ban maintained that because a semiautomatic handgun could potentially be converted into a machine gun a class of firearms not expressly protected by Heller they were in fact machine guns and therefore not protected by the Second Amendment.

WSJ: Jeffrey Scott Shapiro: A Gun Ban That Misfired

The guns covered by the original were not the fully automatic machine guns used by the military, but semiautomatic versions of those guns.

WSJ: John Lott: The Facts About Assault Weapons and Crime