CNN reported that an AR-15 shotgun was used in the Navy Yard shooting. That first Twitchy response is the best:
Everyone knows that Manti Te’o’s girlfriend was a proud owner of an AR-15 shotgun.
(Trust me: if you’re a college football fan, that comment is hilarious.)
My theory: due to alpha-numeric dyslexia, illiteracy, and innumeracy, CNN merely confused the AR-15 with the AA-12:
There is, of course, only one rational response to that video.
World's Only Rational Man 
I stick with gross incompetence and pushing an agenda. For these guys “gun” equals “think of the children!” It’s like a bunch of old hysteric bats.
Why must you burden us with truth when we’re riffing on fiction?!