There are too many unknowns about the "good samaritan" to make reasonable conclusions. We don't know his shooting background. We don't know what ammo he was using. One thing is for certain, he knows the basic fundamentals of marksmanship to make 80% hits at 40 yards! He had a cool head and situational awareness under extreme duress. I doubt that a short barreled revolver would have been manageable at that distance for even very experienced pistoleros. We'll just have to wait to see what Massad Ayoob has to say after he investigates.