TNT was not designed to kill but it certainly can do that well. But since you are focusing on design then you have no argument on preventing me from purchasing TNT right? People calling for more gun control never fact the fact that gun control has not shown to save lives. (generally speaking)

Gun ownership is a right as is clearly stated in the constitution but that is just 1 reason for firearm ownership. Your logic is flawed, defending a constitutional right is not responsible for gun deaths. I want to take away your car and if you say no then you are responsible for car accidents. 

If you could get rid of all guns then of course gun deaths would go down, but people will still be violent. Banning cars would cause car accident deaths to go dow. Banning all coconut trees would eliminate all falling coconut related injuries, etc etc. But fact is you cannot get rid of all guns, there will always be bad guys with guns. I would rather be the good guy with a gun to stop him