I think you're making the argument that with more guns, countries tend to have fewer gun deaths per gun. This makes sense, casually. However, I doubt that anyone cares about the number of gun murders per gun, but rather the total number of gun murders, which is (please correct me if wrong) still correlated with more guns.

Also, I see that you've focused the discussion on gun murders, which is fine, but we should note that decreased gun ownership does lead to far fewer gun deaths, mostly by reducing suicides.