As always, "correlation is not causality". However:
-- If gun crime had gone UP, do you want to place any bets on how we would be hearing about it?
-- MULTIPLE CASES of correlation, along with a good potential mechanism for WHY there is correlation IS highly useful. If the same standard was applied to "smoking causes cancer" as is demanded of "more guns less crime", we would still have cigarette ads on TV!
The left wants guns removed for the same reason that they want people that don't agree with their stand on gay marriage to lose their jobs.
C O N T R O L !!!