I am sure the source is genuine, the GAO, but the link is to the "left":
Under current laws, if a background check reveals that your name is on the national terrorism watch list, you’re still free to walk out of a gun dealership with a firearm in your hands — as long as you don’t have a criminal or mental health record.

Data from the Government Accountability Office show that between 2004 and 2010, people on terrorism watch lists tried to buy guns and explosives more than 1,400 times. They succeeded in more than 90 percent of those cases, or 1,321 times.
Link:http://thinkprogress.org/justice/201...rist-guns-gap/