I just got my da556 and I've had it out once, this is my first AR platform rifle and was pretty happy with how it performed. The trigger was very heavy/rough. After I cleaned it I watched some youtube videos on how to disassemble the trigger assembly and how to polish the engagement surfaces. When I took it apart the I could easily see some pretty deep machining marks on them, they were easily felt when I rubbed my thumbnail over them. I carefully stoned them smooth then polished them with my dremel tool and the trigger feels waaaaay better. I'll probably be heading out to the range with it this weekend.