After the defeat of the Manchin-Toomey background-check bill, and the subsequent demonization of the Senate, Senators Manchin and Toomey are reportedly back at work on bipartisan legislation addressing gun control. John R. Lott, author of the new book At the Brink, who has been researching gun policy for decades, talks about the state of the debate with National Review Online’s Kathryn Jean Lopez. Kathryn Jean Lopez: Gabby Giffords has accused the Senate of being in the grips of the gun lobby. Is there another explanation for the defeat of the Manchin-Toomey bill? JOHN R. LOTT: Yes, there is. The politicians...