Let me start by saying that I'm not an expert on our laws here in California as I've only been into firearms since last year. Our Assault Weapons Ban bans various rifles by name, such as some Bushmaster AR-15s and I believe anything with Kalashnikov in the name, as well as many other "assault rifles". In addition to the named rifles, assault weapons are banned by features as well. For instance, if a rifle has a detachable magazine, it can't have features such as a pistol grip or a flash hider or a thumbhole stock. The way that we're allowed to have AR-15s and AKs is through off-list receivers.