Recently, A Democrat senator suggested that he has no idea why anyone would need to have an assault rifle. His ignorance is the premise of his decision to limit the 2nd amendment. To me the answer is pretty easy.
I would own an assault reason for the exact same reason I would own a superfast sports car that is built to exceed legal speed limits. So that if the Chinese drilling off our coast where we are not allowed to ever decided to sneak soldiers and nukes into the gulf instead of oil rig workers and equipment and invaded Florida blitzkrieg style, I'd have a chance of getting out alive.
Seriously though, would you own an assault rifle? And if so, why?