The term used by idiotic people who cant respect the fact a person likes something Guns
Also, a "Gun Nut" is often a normal person, but gets a negative label simply because of other peoples intolerance to their interests.
Shooter "i like firearms, ive been a sports shooter for 10 years"
Anti-Gunner "Oh great, another gun nut"
Shooter "And?, do I think of rude terms to call you by if I dont happen to like what your doing?"
Anti-Gunner *goes on about how he will shoot lots of innocent children because he owns a gun - despite the fact hes owned a gun for 10 years and noones died yet*