Pro-gun groups sue to stop enforcement of new Colorado lawDENVER — A pair of gun-rights groups have filed a lawsuit against Colorado Gov. Jared Polis to block enforcement of a new state law banning so-called “ghost guns,” in the latest legal challenge of a slew of new firearms reform measures. The suit was filed in federal court Monday, when some provisions of the law took effect, by three Colorado gun owners and by the National Association for Gun Rights and Rocky Mountain Gun Owners. It alleges that the law violates the Second Amendment and doesn’t comport with America’s history of firearms …