Assault weapon means:
http://www.ar15.com/forums/topic.html?b=8&f=9&t=307707
Any of the weapons, or functioning frames or receivers of such weapons, or copies or duplicates of such weapons, in any caliber, known as:
Norinco, Polytech, and Mitchell Avtomat Kalashnikovs (AK-47’s);
Action Arms IMI (Israeli Military Industries) Uzi and Galil;
Beretta AR-70 (SC-70);
Colt AR-15;
Fabrique Nationale FAL, LAR, and FNC;
SWD M-10, M-11, M 11/9, M-12;
Steyr AUG;
INTRATEC TEC-9, TEC-DC9 and TEC-22;
Revolving cylinder shotguns such as (or similar to) the Street Sweeper or Striker 12
What this list means is post-ban Colt rifles with an “AR-15” roll mark are not legal. Note: If the rifle is marked “Sporter” instead of “AR-15,” it is legal despite the fact it is the same machine. Again, pre-bans are exempt.