Just heard on the Wednesday night news that the "shooter" as he dubbed himself before opening fire, stole the AR from someone he knew and experienced several stoppages, jams and malfunctions during his attack on the Oregon mall. I get the impression neither he or the weapons owner knew about semi-automatic rifle maintenance. I would be so proud to hear of some citizen, off duty LEO, armed service member, security guard or the like leaning out slightly from behind cover and dumping say , half a pistol mag into one these miscreants while he is frustrated with an unexpected weapon failure.
Or it was a Rijas