You're saying homicides have historically varied in the US by a factor of 2, and this variation cannot be correlated with notable changes in gun availability. Previous comments mentioned a factor of 10 difference in homicides compared to countries in Europe, arguably with the most notable explanatory correlation being gun availability. If the only crimes we are talking about are homicides, then there does seem to be a pretty good case.
Some people thrive on the empowerment, liberty and responsibility associated with these incredible death machines. But that's no reason to mistreat the data. For instance, the ratio associated with other death machines like cars, which have somewhat similar availability across the pond between US and Europe, is a more reasonable factor of 2/3.