The right to bear arms in itself would be meaningless if it did not imply the right to fire them. This would be tantamount to saying that the First Amendment right of free speech meant only the right to have organs of speech, not to use them. And if the right to bear arms was really granted to the states or to individual citizens as a means of self-protection against oppressive government, it logically follows that the Second Amendment protects the right not simply to fire guns at targets or at deer, but at oppressive federal agents. Such a right of killing would be strange, unique and surprising for the founders to have wished to include in the Constitution. And very impractical.
Some killings are, of course, considered legal and justified as self-defense.
But society, under the framework of the Constitution, has appointed its judges, who are government officials, to determine when a killing is self defense and when it is murder. It is possible that the right to bear arms was the least well thought out section of the Constitution, and that the drafters would be horrified if they could see the gun violence in our cities today and then hear the sanctimonious use of the Second Amendment to sanction the means of killing. It may be possible to ban guns entirely, without doing any fundamental violence to the Constitution. For every noble amendment, such as the one confirming the freedom of the slaves, there are silly or trivial ones such as Prohibition. Today, with calls for a Constitutional amendment requiring a balanced budget, or the right to school prayer, one can only be glad that it is hard in general to amend the Constitution, or else it would become a tattered patchwork and cease to have much to do with its original beauty and intent.