Some people seem to equate requiring any kind of background check as taking away Americans' right to defend ourselves. Some people want more control.
Personally, I think the whole debate is a distraction from the real issue. The root of the problem is: guns are legal in America, therefore there will be shootings.
You can require background checks all you want, but most people who commit shootings are either not insane, used someone else's gun which was purchased legally, or have no prior record. So long as guns are legal in America, people will use them on one another.
Stop arguing that bad people will find a way to kill with or without guns and the only thing that stops a bad guy with a gun is a good guy with a gun and face this fact. Take a few days to let it sink in. The United States has a gun problem because guns are legal, not because bad people keep getting their hands on them.
We're never going to use guns to overthrow a tyrannical government, or stop a mass shooting. They may be good for home defense, but let's face it: most burglaries happen during the day, while you're at work. As long as guns remain legal in America, people will be shot. That's it.
I don't have a problem with guns. If you want one for home defense, that's fine. If you want a hunting rifle, that's also fine. But with this freedom (which is not unique to America, by the way. Plenty of other nations have guns, too) we must accept that people will be shot, and there is no way to separate the good gun-owners from the bad ones.
The second amendment was about states maintaining their own militia, not individual gun ownership. It was written before the modern city even existed, let alone weapons that can fire more than one shot per minute.
At the very least, it needs to be updated to adjust for the changing times. Regulation and moderation is not the same as infringement. But as long as business interests keep shaping our politics, the powers that be will always twist the argument into an emotional one.
Stop it. Let's all please stop being shocked when another shooting happens. Let's stop arguing the same things again and again and just accept that this is an inevitable effect of gun ownership as a right.