How about we compromise then(something politicians are unwilling to really understand)? Make it a requirement that the original purchaser is held liable if the firearm he purchased is used in a crime(If he is unable to prove that he made a reasonable effort to secure the firearm, say it was not in a properly installed and locked safe), and that ALL sales must go through an FFL(for a background check). Lets also add in that if a person has had more than 3 incidents of their firearms being stolen, they are placed on the denied list for NICS. In exchange allow private ownership of machine guns again.
"I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it." Thomas Jefferson