2/3rds of deaths due to firearms are suicides this ratio is even higher when you adjust for the accidental discharge which is quite often used when there is no suicide note or a clinical history.
Mass shootings are indeed a drop in the ocean as far as gun related deaths go in the US.
https://www.huffingtonpost.com/evan-defilippis/do-we-have-a-...
I live in a region with a real low rate and most of the cases in the news involve people that know each other. I've thought about trying to gather a profile of each incident, working back through time, to try to get a picture of the statistics rather than just relying on my impression. Of course, on top of being a fair amount of work, there are also issues with what sorts of information is ethical to consolidate like that (and especially, names of accused; my driving interest is the relationship statistics, so that is a core issue).
So most proposed regulation of firearms wouldn't make us a whole lot safer, because it wouldn't address people getting angry and getting their licensed pistol.
(the point being that addressing mass random homicides won't actually make us a whole lot safer...)