You ask a tough question. Bear in mind that the ATF killed more kids at Waco than the majority of mass shooters have. When you look at the sheer numbers, rather than hype, you have a different picture. As I see it, there are two possible solutions. 1) Allow each state to determine what laws they wish to have regarding guns. The national "one size fits all" solution does not work. Look at how many gun laws there are in Chicago and how many murders there are. That is a statement of how more gun laws are not the solution.
2) The other possible solution is the Swiss solution, which is requiring each home to have a gun. This would likely upset some people since not everyone is comfortable with tools like guns in their homes.
There will be supporters and detractors for each of these possible solutions. There is also the confusion of the gun issue with the mass shooting issue. In terms of what you mean by the gun issue is not clear. Is the gun issue access to guns, the excessive involvement of government with guns, the lack of timely armed response or something else? Of course when there is a crisis, you call 911 wanting someone with a gun to arrive in 15 minutes later rather than having access to a gun yourself in responding to a situation where seconds are the difference between life and death. The connection between mass shootings and pharmaceuticals is also one that can not be ignored. You make a connection with mass shootings and guns, without including the key variable of drugs and their influence on the minds of the shooters.