People use the term "assault rifle" to mean "assault weapon rifles". It is a very widespread usage, including by politicians and the news media. It is also a very logical usage – it is simply shortening the phrase by dropping "weapon", which is kind of duplicative given it includes "rifle". Yes, this contradicts with the older military usage of the term "assault rifle" – but different people use words in different ways, language evolves, and insisting other people are wrong for using words differently from how you do is just ignorant linguistic prescriptivism.