That is what got me, there is no mark in front of the rear sight. My Bushmaster upper does have a mark on it. This one doesn't.
The rear sight is loose as loose gets. It sits cockeyed and as you turn the sight up it striaghtens up a good bit. Also the rear sight starts out on the 500 meter mark instead of the 300/800 mark. I picked this up at The Ernie Bean gun and knife show in Jackson Mississippi about 4 or 5 months ago. I took it to a local gunsmith and he recomended scrapping it. I was going to try to figure out who made it and see if they could make the sights good.