If I remember right it was NBC that originally came up with the cop-killer bullet lie, and then the other big lie machines picked up on it. At the time no cop had ever been killed with one, and I assume that is still true to this day. But the slogan still led to a law being passed (though the original was watered down).
Ghost gun looks like another slick advertising slogan, to go along with saturday night special, cop-killer bullet, plastic gun, assault weapon, gun show loophole, and so on, with each slogan having a big lie campaign behind it so ruthless it would embarrass Josef Goebbels.
Motto of the liberal press: ye shall know untruth, and it shall make you unfree.
Thank God enough Americans are on to these liars to have elected a loyal American as President. Now their antics are less dangerous than they are humorous.