I once had a friend—a guitar student of mine—who was also a gun enthusiast. I joined him a number of times at the firing range, bought myself a target pistol, and thorough enjoyed popping holes in paper at 25 yards.
But my friend carried a Colt .45 automatic with him at all times. He had a concealed weapons permit, and he was never without the pistol. His wife told me that he even slept with it on the bedside table.
There were a number of incidents. One night he very nearly shot a mutual friend approaching him whom he did not immediately recognize. Out with the .45 and drew a bead on Buzz's chest and was about to pull the trigger when he suddenly realized who it was.
Another time, he whipped out the .45 and took aim at someone trying to flee from a hit-and-run accident and got himself arrested by the police, who already had the situation in hand. My friend (ex-friend—I came to the conclusion that he was just too damned dangerous to be around—and his wife divorced him after a couple of years of marriage) was arrested by the police and his gun was confiscated. And his concealed weapons permit was rescinded for a three month period. He was told by the judge, in no uncertain terms, that the hit-and-run accident did not justify the use of lethal force.
So I know this kind of person.
They have a gun, they fancy themselves Defenders of Law and Order—and they are itching to shoot someone!!.
A black teen-ager, walking in the evening, wearing a "hoody," and carrying "something" in his hand (a box of candy he had just purchase at a convenience store), and Zimmerman assumed was casing the neighborhood, was just too big a temptation!
The police told him to cool it, but he went ahead anyway.