If you are going the low power variable optic route, take a look at the Primary Arms 1-8 ACSS. They have 5.56 BDC and ranging built in to the reticles. They have them in SFP, FFP and Platinum version made in Japan with a 34 mm tube. I have several of the 1-8 SFPs on mine and like them a lot. Their reticles are very well designed.
I bought the Primary Arms 4x14x44mm ACSS HUD for my 308AR. Dang cool scope for the money and I can range anything out to 600 yards.
