Sorry, I wasn't clear. I've got a set of Troy Ind BUIS on another rifle. So I'm familiar with them. I'd have to buy another set if I wanted them on this carbine as well.
As I stated in my initial post, the Hayes Research sights sit really, really low. Especially the rear sight. It's difficult to crane my neck down to the point I can see through them.
I'm a little fuzzy on the physics involved, but...
I'd like to replace the Hayes Research rear sight and retain the Hayes Research front sight. Since the Hayes Research rear-sight is adjustable for elevation and the Hayes Research front sight isn't, I think I'd like the replacement rear sight to be adjustable for elevation as well.
I'm not at all clear whether I'll have to raise the Hayes Research front sight to be compatible with a "normal" A2-style elevation-adjustable rear sight.
For grins, I stuck a LaRue rear BUIS (obviously not adjustable for elevation) on my receiver and it seemed to line up just fine with the Hays Research front sight. I haven't had a chance to check the zero though.
Mike