david small - // Musing to myself…..I wonder if when captured they were publicly executed in a most horrific way. Would that deter such evil actions in the future? //
No, for one very simple reason.
No-one who commits a criminal act, from scrumping an apple to massacring several dozen innocents with a high-powered rifle, does so with the notion of consequences in their mind at the time.
If anyone thought about consequences, they would not commit the crime in the first place, but crimes are not committed by people who rationalise and consider the results of their actions - that's what makes them criminals in the first place.
Your solution would require the consequences to be registered and remembered by the potential gun nut, and to be forefront in his mind when he pulls the trigger, or rather does not pull the trigger.
That requires rational thought processes to be at work, and let's face it people who carry guns in public are, by definition, devoid of anything approaching rationality.