Many 'blue' states are very 'white' and already have a low crime rate. Also, many of the those states have high density populations, where gun violence is actually rare.
While some of the least popular states are 'red', their gun violence and murder is higher due to the high gun ownership versus population and general higher crime rates.
Murder rates are not high due to gun ownership, but rather to demographics and the cultures therein.
The murder rate among Norwegian-Americans is comparable to that of the country of Norway. Think about that.