This is another case of the ATF out of control. It appears they didn't even try to determine the facts before they broke down this guy's door.
The basic AR-15 is a fully legal, semi-automatic rifle. You get one shot for each pull of the trigger. It appears the "sear," which is a component of the trigger assembly, may have been worn and eventually failed, therefore allowing a double discharge with one pull of the trigger. Solution: get the rifle repaired. Apparently, someone noticed this and reported it to the ATF and they jumped to the conclusion it was made to fire fully automatic.
Now, while some people do intentionally alter such firearms to fire fully automatic, which is, indeed, a felony, it seems this man did not. Of course, we would like to think any responsible government agency would ask a question or two before licking in the guys front door, especially since the guy has a clean record. I guess those things are just too easy to check out when you're in the mood to play gestapo!
Perhaps we are headed for a police state, after all.