On Wednesday, in a reference to the possible expiration of the federal assault weapons ban, syndicated columnist Molly Ivins included this line: “Just what we need in this country, more automatic assault rifles.”

As several readers have noted, an automatic rifle is one in which the weapon continues to fire as long as the trigger is pulled and held. In other words, a machine gun. Machine guns are outlawed under federal law enacted in the 1930s; they would remain illegal even if the assault weapons ban is not renewed.