The gun rights view of the world is based on a simple, Manichean duality: there are people in the world who deserve to be shot, and people who have a right to bear arms in order to be ready to shoot them. Gun rights advocates naturally believe that they themselves constitute the latter class. Who is the former?
In studying gun advocates' stories of justifiable shootings, and of regrettable but morally blameless shootings, one finds a huge divergence between the people whom the law says one may shoot and the people gun advocates believe it is permissible to shoot:
People who punch you
In Dallas, in what most Texans seem to accept as a vindication of the concealed carry law, a large man who punched another through a car window after a fender bender was shot by the driver with his legally carried concealed pistol. I heard Texans complain with incredulity that liberal Easterners were using the incident as an example of the evils of the concealed carry law, rather than an obvious example of why concealed weapons are a good thing! I learned in law school that deadly force is only justified in self-defense against deadly force. Raise your hand if you think that the victim of the punch would have been unlikely to survive the encounter--or couldn't merely have driven his car away. The shooter was not indicted, however. The subtext here is not so much self-defense as the idea that it is acceptable to shoot people who punch or otherwise humiliate or insult you.
People you provoke into attacking you
In Los Angeles, a vigilante who went out night after night armed and looking for graffiti artists stopped and verbally threatened one, who finally ran at him with a bottle. The vigilante shot him. An outpouring of citizen sentiment supported this man, despite the fact that he clearly was searching for someone to kill, under circumstances where he would be able to argue self-defense. The subtext here is that graffiti artists and other riff-raff deserve death. After some flip-flopping by the authorities, this man was charged with the killing.
Children who jump out of closets
One recurrent theme--I have seen several iterations over the years, including one recent one in New York City and another in the South--involves the man who comes home and is surprised by his teenage daughter jumping out of a closet to frighten him. He whips out his pistol and kills her reflexively. He is not indicted. We love our children but, really, she should have known better than to scare him. The subtext is that the occasional killing of an imprudent child is an unavoidable accident in our gun culture, and not really anybody's fault.
Tourists who come to the door
A similar incident involved the Japanese boy who came to the door to ask directions, frightening the homeowner. He should have known better than to go up to a stranger's door--or to keep walking despite being told to freeze. This man also was not indicted.
Women who fail to wear orange on the front porch
In Maine, a hunter shot a woman who was standing on her front porch. The locals complained that the woman, an out-of-towner, should have known better than to stand on her porch, not wearing orange, during hunting season. The hunter, who to an ignorant Eastern liberal lawyer seems arguably to have been grossly negligent, hunting within a few feet of a house, was not indicted. The deaths of a few incautious outsiders during hunting season are the price we pay for liberty.
Thus there are two basic classes of people it is acceptable to shoot: bad guys and the unintended victims of "friendly fire." Of course, in an extremely ambiguous world with many moral shadings, it is awfully hard to tell who is a bad guy. The difficulty of looking into someone else's soul in the instant which you have to make the decision means that you have to use shortcuts--rely on obvious external hints, such as the race of the other, the way they are dressed--or even the speed at which your daughter is coming at you out of a closet. If you didn't have the gun, you wouldn't be making the decision. Not one of the incidents above would have resulted in the shooter's own death. These victims did not die so that someone else could live; they died for your right to carry a gun.