Gun control won't work - you've already got the guns on your shores. You've already got the culture of using guns to solve problems. The US fetishizes guns, holding them up as a symbol of power and masculinity. The willingness to use guns, the sheer enjoyment that comes with using guns, the feeling of power that comes with gun ownership is too rooted in US culture to be removed.
I would be in favor of passing US gun laws.... if I had a time machine and I could go back 150 years to do it. Back then, it would have made a difference. Now, however? It makes no difference at all. The guns won't stop coming in, the criminals already use them, the public still wants them.
I'm glad my nation, Australia, has avoided such a mess. Surprisingly, we've remained a democracy even with very low levels of civilian gun ownership! That's right, we haven't had to fight off our government, and almost certainly will never have to. We're not paranoid about "government-takeover", unlike Conservative Americans who believe that anytime the government does something they don't approve of, it's evidence of the death of liberty itself!
But on the shooting - terrible. Terrible tragedy. You've got to wonder why such things happen with more frequency in the US than in Australia... UK... Japan... Ireland... Norway... Belgium... or most of the developed world. That's not to say that we don't have mass shootings in other countries - I'm just saying that they are a whole lot rarer, even when taking into account population differences.
Look, America, I love a lot of things about you. Your constitution is still one of the greatest, if not THE greatest political documents in all of human history. I marvel at your size, your achievements, your science and your universities. I love the sense of optimism that some Americans still retain. I love many aspects of your culture and history and I can safely say that I wish to never see America fall. I wish you success and continued prosperity.
But that doesn't mean I agree with everything you do, nor does it mean I think you're perfect. On gun culture, the US has something very, VERY wrong with it. Why are guns so widely used? Why are your people so angry? Few other developed nations have this problem. Your culture, previously orderly and optimistic, has turned sick and cynical and angry. And it hurts me to see that - to see a nation of people who looked up and forward, a nation which believed in civility and civilization (at least at home if not necessarily abroad) turn into a nation of angry, angry people who hate each other over relatively minor things. A nation full of people who feel so insecure, so pathetic, that they seek refuge in the power that holding a gun can give them. That feeling of raw power, the feeling that their gun makes them a "badass". You can't deny it - even among responsible gun owners, there is a allure of the "power" of a gun. Just see those photos of men and bikini clad women posing with their assault rifles, trying to look as menacing and "badass" as possible. You've created a culture in which people feel powerful with guns, and feel that they have to use them to feel powerful and "respected". That culture is poisoning you, America. Your culture of violence is your worst enemy.