It can only be a national issue. As long as the answer is "I'll just go over there and buy a gun" no meaningful gun control can possibly exist. See what's going on in Chicago currently to see this dynamic in action.
Gun laws there are confounded by so many other factors in general crime and murder rates that I doubt much useful knowledge can be discerned until some number of years pass as the city returns to US norms of gun ownership and concealed carry.