Can you imagine the response if Congress passed a law that said you must complete "voter training" prior to each election before being allowed to vote? Because we all know that there are lots of voters who know absolutely nothing about the people and issues they are voting on, simply voting as their party wishes. And what if the voter had to pay for that training? Do we set aside the Bill of Rights for the overall good of the country?
I get that there is a big problem with shootings. But these gun control measures do nothing other than make politicians points with their constituents. Live in a state that bans assault weapons and >10 round magazines? Go to a state without those restrictions and buy what you want - if you're going to commit a crime, why care that you are breaking the law by doing so? Anyone with a little mechanical skill, a hobby lathe, and a 3D printer can manufacture a fully automatic gun. And imagine the carnage if an unbalanced person waited for a windy day, stole a gasoline tanker, fitted it with an electric pump and nozzles, then started a huge wildfire just upwind of a major city. Take away guns and the crazies will turn to other means of carrying our their killing spree.
Want a real solution? That's going to cost you. Universal mental health care, free education and job training, and programs to find "loners", who are involved in most mass shootings, then evaluate their risk to the public and themselves.