Three, and that's in consideration of it's new-found modularity. They are a PITA to clean properly, I know, I had to redo tons of them that soldiers thought were clean, or sit in the Arms Room waiting for them to get them right themselves. To do it right, you need specialized cleaning tools and expendables (carbon scrapers and long pipe cleaners come to mind), and have to remove small, easily lost parts to do it.
5, 4, 3, respectively.
I'd give it a four strictly as a civilian rifle; they are usually better taken care of and the modularity is a great asset.