Well, just because you have a gun doesn't mean you have to kill someone, and I'm pretty sure there are circumstances under which you can kill someone with a taser.

But, since 1934 there have been some dramatic changes in the technology of firearms.

Is there any line that should be drawn at all?  

Note that the Supremes always specify that these weapons must remain in the home for self-defense of one's life and property.  Start talking about outside carry and you start talking about restrictions such as the horror of registration.