That's a common misconception. Assault rifle refers to a firearm that (among other things) has selective fire ie user control over rate of fire for semi automatic, burst, or full automatic. They're illegal to purchase and pretty much illegal to own...those guns are strictly military weaponry, and although they may have civilian variants that do not have selective fire those are what people are referring to when they talk about 'assault weapons' primarily: semi automatic military-styled firearms, usually rifles, without selective fire.