Well, there are practically no 55-gr FMJ cartridges currently being fielded to our US Military forces, and that's what WWB is.
I would venture a guess that US commercial loading operations have been shifted to the heavier penetrator bullets to fulfill government contracts for faster-twist M16-A3s and M-4s.
You might still find 55-gr Winchester Q3131A (manufactured by IMI in Israel for Winchester) on some of the various online sites or at gun shows, usually priced about $4/box. It is Milspec, unlike the Wal-mart WWB or Remington yellow box UMC. But it's not NATO spec because there is not an inspector signing off on every lot number.
Still, it's really good stuff. Don't let the appearance of the brass turn you off. It's not polished as well as commercial ammo but Q3131A is damn good.