ok guys took me a couple of days to get back due to work.
This is my M4 OPS before I added the front gas block. The huge scope was a left over and I have replaced it with a smaller on but your get the idea.
OK... the fwd asst is non functional. the dust cover will not latch in up position. the receiver is cut out there.
on the outside it has just about all of the same options as a true AR chassis.
Like others have stated, as long as it is a brand name rifle you should be good to go for accessories.
My flip up sights turned out to weigh over a lb. that t handle is not light either. that is the one true drawback. it is easy add so much weight that one does not want to carry the things. something to consider