Right, guns themselves don't kill people; people do. A very valid argument.
Who can have a gun, and who cannot?
Currently, if you've committed a felony violent crime or beat your wife, which I suppose is a misdemeanor in some places, you can't has. No gun for you! (seinfeld)
If you are currently smoking the pot [or other drugs], illegally or otherwise, you can't has.
If you wanted to hang yourself, you can't has.
But it asks nothing about, "Are you a Jihadist?" or "Are you currently, or ever plan on, being off your rocker?"
How do you control that? Do you make it subjective to the gun dealer selling the firearm? Then you open the door for profiling.
Gun control is a very tough argument, in either direction. Obviously we can't get rid of guns, we can't ban them and we can't profile people. So what do we do?