If guns aren't a problem, how come the US has (many!) hundreds of percent higher homicidal, suicidal and accidental gun deaths than any other western nation? There's an elephant in the room, and you refuse to see it on purely ideological grounds. You're not making sense.
Limiting access to guns won't stop "sick fucks" (mentally disturbed people), but you know what? Nobody ever said it would. Flawed strawman logic at work there matey. What would happen though is that without access to high-capacity magazine firearms, said "sick fucks" would have a lot more difficult time killing as many as a dozen or more adults or children.
I think anyone would agree that it's a lot harder to commit mass murder using knives than it is using guns. Yes?!
if guns are the problem then why do most of the states with homicide rates comparable to western european nations have the most liberal gunlaws (liberal in the true sense of the word) whereas some of the worst states have the toughest gun laws. how does that compute? and when you break the US down even further you'll see that there is absolutely no correlation between the availability of legal firearms and homicide rates.
as for "high capacity magazines", they are outlawed in Norway but Breivik only had to wait a couple of days for them ship to him from the online seller...
look at the Boston bombing, no firearms were involved in that act of sick fuckery and we should be thankful that due to the absolute incompetence of the bomber(s) only 3 innocent people lost their lives, had someone else built and deployed those bombs the death toll could probably have numbered in the hundreds.
you say we should learn from bad experiences, but guess what? We have, treating a symptom does not cure the illness.