The first step to finding solutions to these mass shootings is to employ intelligent, critical thought. Next, it's crucial to acknowledge reality.
Reality is, criminals and psychos don't give a shit about gun free zones and gun control laws. They don't care if AR-15's - or all guns, for that matter - are banned. Reality is, if some wacko wants to go mow down a bunch of kids at a school, he WANTS schools to be gun-free zones. He WANTS nobody to be armed anywhere in the vicinity. Why the hell would intelligent people of sound mind want the same thing?
Reality is, we can ban AR-15's. We can ban this and restrict that, and tighten background checks to the point guns are harder to get than an appointment at the VA clinic. But it won't do a bit of good.
Reality is, there are HUNDREDS of MILLIONS of guns already out there in private hands. And the owners of those guns are NOT going to just hand them over if someday the government decides to start a confiscation campaign.
Reality is, government won't even attempt it, because it's unconstitutional, and it would be a suicide mission requiring FAR too many law enforcement resources. As such, the reality is that it will NEVER happen.
So, any solutions need to start with acknowledging those realities. The path is pretty clear if you're an intelligent person that employs critical thinking on a regular basis.
Or, you can sit there in your underwear, clutching your bag of chips and drooling on yourself, while allowing CNN to tell you what to think. Which is what far too many people seem to be doing.