It's whatever the gun-grabber says it is. The term is intentionally ambiguous so that it can be defined and repeatedly redefined over time. Each successive redefinition will have a broader meaning. I've seen "assault weapon" legislation that included a semi-auto pistol with 11 or more rounds.
time to help the economy and put more weapons under the tree. Bammy, will ya send me ma stimulouse check so i’z can buys me another can O’ commie whoopass?