Someone on Bookface a few days ago had a big thing about "They have strict background investigation, and you have to have a REASON to own a gun", etc. The slight problem being that people planning things like this don't care, as they aren't exactly following the law when they obtain these things.
I get really tired of arguing this stuff. It's always someone who says "We only need a FEW more laws, and then everything will be wonderful!" And since guns are icky, and anyone who owns them is icky, or derelict in brain cells, or both, it won't bother them at all to have those few more laws shoved through, until the last one says "You can't have one. Ever. At all." And when that doesn't stop the bad guys(or suicides, or fatal accidents) there'll be something else needing restriction or banning, because it's always something that's responsible. Because holding someone responsible is uncaring, or bigoted, or something.
There'll always be 'Just one more law will do it!' coming from them. Because blaming objects for what people do won't solve anything, it'll just mean the law-abiding people won't have something anymore.