Nikon has a great scope for a .223 rifle, such as your AR-15.  They call it the “M-223”.  It’s slick and easy to use.   It’s actually one of my favorite optics for any longer barreled AR build (Think Crusader Templar) or Varminter configuration.

What does Nikon have for AR-10/SR-25/Broadsword?  Nothing so much… Right now for a Broadsword I’m thinking a PFI RR800.

What Nikon needs to do is a .308 specific scope, much like the M-223… but with an illuminated reticle.