The gun laws are not the problem in my honest opinion.
In Switzerland, it is compulsory for every single man to do military service, and then after their service to keep a military grade automatic assault rifle in their possession. Bare in mind that fully automatic assault rifles are banned in America. Yet Switzerland has one of the lowest rates of gun crime per populace in the world.
I really think the problem is a mental thing, and I think the education system in America is the biggest culprit unfortunately. Obviously being an onlooker and never actually experiencing it, I cannot be completely credible, but the impression I get from movies and stories about highschool in the US is that even from an early age kids begin to alienate each other. Kids are encouraged to huddle into social groups where it is a competition to be the most popular arsehole. The smart are not so sociable people are then bullied and alienated from everyone else. This is a recipe for disaster. These kids that do these hideous acts are never the popular cool kids at school, as far as I know, and are always the "losers" at school.
Now clearly not everyone who got bullied or was unsociable at school turns into a mass murderer, so there are obviously other elements coming into play. Perhaps some people who already have underlying health issues are more vulnerable to go off the rails when put into this social environment.
Don't get me wrong, I am not sympathizing with these shooters, Adam Lanza was a hideous monster and the world is a better place without him, but the education ministers are also at fault for allowing a situation to be created where those with already damaged minds can become more twisted and turn from an angst filled reject to a horrendous killer.
Society as a whole is breeding these kinds of people in my opinion.
In terms of the gun laws, what I feel is a very valid point is that these people never wander into a military base and try to kill heavily armed soldiers who are prepared to fire back. What do you think will deter someone from walking into a school with the intent to kill? A sign that says all guns are prohibited from the school, which tells the murderer there will be no resistance? Or a sign that says there are heavily armed and trained marshals on site who are prepared to fire on trespassers?