I don’t know if your proposed gun control measures will reduce mass murders, but I doubt it. They are a meek attempt to attenuate one of the symptoms of the problem. And will mostly impede those who wouldn’t ever do such a thing.
I do know that until Obama stops the wholesale manufacture of terrorists by murdering their wives and children in his weekly drone attacks, until the nations of the world stop responding to violence by individuals with massive violence against innocents in their countries who had no part in it, until the state starts practicing peace at home, instead of mass incarceration and destruction of civil liberties in response to a personal psychological problem (the war on some drug users), things will continue to get worse.
Physician, heal thyself.