I agree, the assault weapons ban did not work. The question that is relevant is why. As long as we fail to address or prove the why part of if then it continues to be a double edged sword.
If you take a medicine for an ailment and you see no effect, do you automatically know that it means the medicine is worthless? Or do you then also have consider dose, conflicts with other medicines, diet, etc?
No! No! No!
People in favor of the ban have no interest in it working. They have one goal: ban guns. As many as possible now, and all of them eventually.
They no more want to identify why the ban was ineffective as you have of doing your own research when it's easier to post questions and wait for others to feed you the answers.
The truth is also something they do not want to hear. They banned a type/class of weapon used in maybe 1% of all crimes. They chose this type for one reason: the AR-15 is the most widely owned rifle in the US. Ban it, you ban a huge number of rifles at once!
Criminals don't use an AR-15 often, and when they do, it's mostly because that's what they happen to own! Ban that gun, and they will use a shotgun or handgun or Mosin-Nagant, because that's what they have or can get hold of!
They did not ban hate, evil, mental illness, psychological problems or alcoholic drinks & hallucinogenic drugs. The guns are incidental to the acts. Take away one means, the person will choose another.
Studying why is not necessary when you already know the cure was never meant to address any real problem.
Agendas are like that. When all you have is a hammer, every problem resembles a nail.