The gun control advocates chose to overlook some details. Adam Lanza did not buy a gun at a gun show through a "loophole." Adam Lanza did not buy a gun from a licensed dealer and slip through the background checks. Adam Lanza murdered his own mother and stole her guns.
We have strict laws against murder and laws against theft. Adam Lanza became a deranged killer before he ever began killing. Then he went to a gun-free zone and picked the easiest victims he could imagine. We need to first react to the mental health issues. Once those are resolved, we can worry about gun laws.