Yes I have a Rock River with an "Operator A2" I liked it alot, so I got one for their LAR-8. It comes with everything..stock, tube, buffer, and spring.
After careful measurement I determined that a spacer approximately 3/8" dropped down the tube before the spring, gave me the proper "Bolt Hold Open" clearance (1/8 to 3/16") and allowed the BCG to bottom out with in the tube and not crash into the receiver...