"Eeeek, an AR-15 !!!"
Most people who whine for "gun control" do so out of fear, emotion, and ignorance. Specifically, their lack of familiarity with guns creates in them a psychological aversion and fear of what they perceive as foreign, scary and taboo.
(Note: While in this video I say that somewhere around three million Americans own AR-15's, the actual number is probably between five and ten million.)