Conservatives mainly use guns for sport, hunting, and defense. Thus, they cannot fathom the idea of changing the US Constitution to make them illegal.
Liberals mainly use guns to kill people. (The VAST majority of fire arm related deaths are carried out by Democrats). Thus, they (at least the nonviolent ones) see guns as something that should be banned. (The violent one's may also want them banned for more defenseless targets as they can be obtained illegally).
The difference in view is based on the projection of each side's own use of the guns.
My compromise solution would be to ban Democrats from owning guns. So many lives would be saved. If only we could take the guns out of the hands of just the perps while leaving them available to those others to just defend themselves.