By fiat? The federal AWB came about because of pressure from the states who wanted the feds to prohibit their interstate commerce.
I thought the AWB was a hysterical liberal knee-jerk reaction to "stopping crime". Just like the banning of guns that hysterical liberals want in San Francisco and Chicago.
By the way, it won't stop any crime from happening. Guns are already illegal to use in the commission of a crime. Criminals will always be able to get guns. Criminals will always commit violent crimes like armed robbery and murder. Any law against guns only harms the honest citizens.