It's worth pointing out that your definition of "assault weapon" covers, say, the Glock 22 handguns used by, among others, the police. They are semi-automatics

It's worth pointing out that your definition of "assault weapon" covers, say, the Glock 22 handguns used by, among others, the police. They are semi-automatics (one trigger squeeze = one round fired, no manual removal of the old cartridge case or manual chambering of the new round) with swappable clips, eliminating the majority of your reload time. It's also worth pointing out that a double-barreled (or heck, even a semi-auto non-magazine-fed) shotgun would not fall under your definition of an assault weapon, and there are few better tools for causing mass carnage in a small confined area, so even if magazine-fed weapons were all magically eliminated, the crazies would still have access to weapons that they could accomplish their goals with.