First, Edward, neither the NRA nor the U.S. Army determines what is legally an assault weapon, the ATF does. The point is, Edward, if you have 2 on that list, it's an assault weapon. A rifle may not have a bayonet mount, but if it has one, any one other item on that list, it rings the bell.
Here is a link to an area down in the ATF site, type bayonet the the search box at the left and the top of the results show the ATF document I quoted. lots of other info easially available from that link. Link:
http://www.atf.gov/firearms/faq/