The gun is a tool-same as a hammer  or a computer. It's all in how one uses the tool. One can use a gun for legal, useful purposes (which, at least for now, includes self defense), or one can use it to shoot up a high school. One can use a hammer to build a cabin, or split his neighbor's skull for the $5 in his pocket. One can use a computer to research cures for a disease, or one to embezzle funds. It's all in how one uses the tools at one's disposal. The central, common line in all of my examples above, is that none of those tools can do anything without human action, therefore, it is the human actor who is to blame for the incorrect, improper, or unsafe use of the tool in question.