To further clarify my original statement, which I stand by, is that the homicide rate jumped after 1960, when it was 5.1 per 100k, to 10.2 per 100k in 1980. US Crime Statistics 1960-2010

The Gun Control Act of 1968 was a reaction to an increase in gun related homicides, as embodied in the assassinations, which most of us remember. If you care to look at the numbers, you will note that it didn't seem to have done much good

The figures on the page you linked to say that the US murder rate is now half what it was in 1980. Which may not be any sort of evidence that gun control legislation did anything, but it does say that there isn't an uncontrolled epidemic of violence requiring everybody to tool up.