good morning, all; got a quick sight question.

picked up a new ar the other day, and went to sight it in yest.  (rock river a4, 20")  anyhow, it has what i assume is a normal fs, and on the rear it has an rra dominator and an eotech 512.  (basically a normal a2 sight stuck on a riser)

after fooling around a little, cleaning the barrel, etc, etc. i can shoot a nice quarter sized group at 50 yards (attempting the ibsz)  sadly, this group was not anywhere near where i was shooting at.  after messing with the front sight post, i got the groups at the right height, but still about 2" to the left.  lots of cranking on the windage knob has helped, but it's almost all the way off to one side, and it's still not quite dead center.  (groups were shot from rest)  

is there a way to change something on the rifle so that it zeros a bit closer to the center?  if i ever wanted to adjust more to the right, i wouldn't be able to, and that bugs me.  any tips here would be greatly appreciated.  thanks!

edited to add:  also, forgot to mention that the entire rear sight assembly can be wiggled a little bit... i thought it was supposed to be fixed and immovable?

1) You are correct that the rear sight should be solid. Are you able to tighten it up?

2) You might have a crooked front sight base that is causing the big windage adjustment.

If you can't get the rear sight any tighter on your own call Rock River and get them to make it right and they can look at the front sight at the same time.

1) You are correct that the rear sight should be solid. Are you able to tighten it up?

how would i do that?  the tiny hex screw underneath the rear aperture?

edited to add:  also, forgot to mention that the entire rear sight assembly can be wiggled a little bit... i thought it was supposed to be fixed and immovable?

Normal to have some movement.   The A2 type sight is spring loaded and should move back to the same point if moved.