One of the formalities during selection into my last MOS in the military was to take a psych-evaluation. It consists of a 500 question test that asks a series of questions, many are the same question only rephrased to ascertain honest answers. I had to take the test twice but each test was different. This test among others was used to weed Timothy McVeigh out of being selected for Special Forces training.
I believe every gun buyer should have to take such a test as part of an application process.
There are some people that never should be allowed to own a gun. One way that California weeds out possible nut-cases is whenever somebody applies for a concealed carry permit you have to have someone vouch for your mental state and your character and they are legally liable for any harm you may do with that weapon, so the reference knows the he or she may be held responsible. I believe that at least 3 references should be required who aren't relatives to qualify. If you can't find 3 people who will vouch for you then you don't get a gun.
Another thing, questions like "Do you have any special needs children in your home.......do you have any close family members who are felons living with you or are currently undergoing psychological evaluation?"
If you want to buy a semi-auto rifle you should have to go through safety and competency classes and questioning by police officials. Like I said before, some people just should never own a gun. Some soldiers shouldn't be allowed to own guns much less civilians. I don't see the need to own a CAR-15 or an AK-47 other than as a collection piece, nothing more. Unless you have your own private range you can't fire one anywhere other than a military firing range anyway. That's just my opinion. I've had team members that I didn't trust enough to want them armed. Most people don't have the training it takes to be safe and proficient with any kind of weapon. Many take gun ownership too lightly. If this kid's mom had been I believe those kids would be alive today.
I don't think taking everyone's guns will solve anything. It will just cause more problems. The problem with the left on this issue is they don't know when to quit. What they want will not end all violence, it will just force those who turn violent to look for other means to carry out their dark plans. Maybe one of us will become their victims because some ATF agent on orders from an overzealous president took our guns. Many people won't stand for it and will board their windows and eventually become a statistic. The better solution is just try to keep as many guns out of the hands of nut-cases. Let's face it, just about every one of them has been nuts. You'd have to be to do what they've done.