The problem in these cases is mental illness. I don't understand why you can't see that.
Go back and look at the headline shootings over the years. I haven't done a tally but I'd bet the majority involved mentally ill individuals.
The onset of mental illness occurs between the ages of 17 and 25. Since it looks like AR's and AK's are not going to be banned, we should ban their sale to males in that age group.
Apply the same penalties for full auto possession. These fines and jail time deter just about every law abiding gun enthusiast.
Of course it's not going to stop all but it should prevent some.