Don't blame the guns, blame the society. Our country has decided that we need to stop teaching children right from wrong, not hold them accountable for their actions (or inactions), not ever make them responsible for anything. Ever.
Add to that parents who are so busy trying to beat the Jones', or simply make ends meet (and that's IF they're even part of their child's life), and we have created a permissive society, that tells children that they deserve everything they want, and can never do any wrong.
Then reality hits. Life intrudes, and shows them that mommy & daddy were full of shit. But since they never learned to deal with adversity, they have no idea what to do, and lose their minds. Add the bonus of so many kids being labeled "ADHD", and doped up throughout school, and you're cookin' with gas, now, baby!
Being a child of the 60's and 70's, I can tell you that we had plenty of guns and ammunition available to us. Hell, plenty of kids in my neighborhood had .22 rifles that they grew up with, and access to more powerful firearms at home, in dad's gun cabinet.....that I guarantee, you knew where the key was located (I did!). But we also had morals we were taught, and rules we were expected to live by......and, most importantly, we had punishments that we knew we would get, if we broke those rules. We actually had repercussions for our actions, that we knew would be enforced. That's sorely lacking in child rearing, these days, and it shows.
Most importantly, we had parents that we knew loved us, and supported us. They wouldn't necessarily cover for us, if we screwed up.....but they would make sure we learned the hard lessons we needed to learn, then make sure that we knew we were still loved. That kind of parenting is a rock that kids can build their lives on, and become normal, healthy, productive members of society. Unfortunately, if we look at most of these nut jobs that decide to make everyone suffer for their misery, we find out they're from dysfunctional homes, and lacked even basic parenting as they grew up.....and then we shake our heads, and wonder how they got so screwed up in the head.
Sorry to say, but it's not the guns. It's the society that is to blame.