Over the last decade, buying an assault weapon hasn't been as easy as it once was. For that you can credit Congress, which decided in 1994 that rapid-fire killing machines have no proper place in American life. Apparently that conclusion has been renounced, for assault weapons are even now rushing back into gun shops. Today marks the expiration of the ban -- and the coming of a great shopping opportunity for gunsters. Never mind that most Americans strongly backed the ban. Somehow, the prohibition was allowed to wither without regard for the public will -- and despite past support from...