In his new book, “The War on Guns: Arming Yourself Against Gun Control Lies,” John Lott methodically dismantles one popular gun-control myth after another. It has been said that a lie told often enough becomes the truth, and a similar phenomenon is overwhelming the gun debate in America. Oft-repeated untruths have formed common beliefs that often sway the debate about firearms. Gun-control advocates have learned that their exaggerated claims are likely to go unchecked by a largely sympathetic media, allowing them to control the narrative and shape public opinion. What is more, as Mr. Lott explains, billionaire elitists like George...