It's not difficult to grasp how a man with a history of gun arrests and mental instability obtained the necessary firepower to commit a massacre at the Washington Navy Yard earlier this week. Buying a gun, or even an arsenal, is exceptionally easy in the U.S. Even so, there are some people who both fail to meet the minimal requirements for purchasing a gun from a licensed dealer and whose relevant personal details are known to the Federal Bureau of Investigation. Since... (GunPolicy.org)