All of the mass shooters have all been on prescription drugs for some sort of psycosis in one form or another. It seem we need tougher prescription control more than we need tougher gun control. Did'nt have all these problems untill the pharmacutical companies began controlling legislation through the legal bribery called "lobbying" and we had guns long before that, but no mass shootings.
I think the problem is not guns or more gun laws, after all look how the 40 year war on drugs has gone and all the tougher laws on that topic.
The problem is pharmacutical chemicals and the allowing of the wealthy pharmacutical companies to control the laws that govern them. Thats where the problem seems to lie and is what really needs to be addressed.