If I had a lunatic running around in my neighborhood killing people I would want to be armed.
The problem the democrats have selling the gun controls laws they are trying pass right now is they have not done a very good convincing people they will have any impact. Like your example here people look at Sandy Hook and even though they are frightened and angry the dots don’t connect. If you cannot get a law through the democratically controlled senate that polls at 90% what are the chances you may want to look at your sales tactic and stop trying to hijack a tragedy to sell it.
While I care about this issue, no one seems to be able to sell it to the deeper public as an extreme priority. Hell people haven't sold me it as an extreme priority.
Deaths by gun happens...it is sad especially since we can probably cut it in half by a change of culture and regulation. Nobody is willing to do what is necessary to cause the change of culture, thus it will not happen.
Yet the sad part is that you don't have to make big changes, you just have to make a lot of small changes on the margin, it is not a hard problem to solve.