I'm not going to get into the gun discussion, but there is also a great deal of talk about mental health intervention, much of it quite naive, IMO. In each case, the recommendations sound good on the surface, but then there are realities that are unknown to people who don't have a great deal of experience with the mental health system. There are many devils in the details. Moreover, the level of public faith in our ability to predict violence is excessive, this coming from someone who has extensive training and experience in in-depth psych evaluation.
Furthermore, when the immediate hand-wringing is done, I doubt there would be wide public for support the costly trade-offs that might reduce the number of mass murders and spree killings. Major financial costs as well as social costs would be involved. And in addition to the more apparent costs, there are less visible secondary costs of many of the proposals. It's one thing to casually agree to these costs up front, but accepting them is quite another matter when the agitated chickens come home to roost.
After following a long thread at one of my daily reads (Eric Zorn), I added my three cents to the discussion. If you're interested, here's a link to my comment.