Laz,
I have borrowed this but it gets to the origion of Democratic Gun Control as a party platform line.
Until Lyndon Johnson came to the White House in 1963 following the assassination of President John F. Kennedy, gun control was simply not a national issue. There were no significant federal gun control laws on the books, and the NRA was a shooter's organization that intentionally shied away from any political involvement.
All of that changed with the 1968 assassinations of Sen. Robert Kennedy and civil rights leader Martin Luther King. In the civil unrest that followed, the media found a new whipping boy – America's gun owners. The media blitz against gun rights was unprecedented and became the driving force behind Democrat leaders proposing national gun control.
Although JFK and his brother, Sen. Robert Kennedy, had been NRA Life Members, America's new president, Lyndon Johnson, was a committed gun control advocate. No president ever matched his power and his will when it came to controlling the legislative process. His attorney general and much of his senior staff searched for new ways to restrict gun ownership among the American people. This was part of Johnson's Great Society vision of an all-powerful federal government controlling the lives of ordinary Americans.