Didn't intend to be rude regarding shooting the AR to 600. Simply don't do it myself.
I just mounted a Vortex Diamondback DBK-04-BDC on my Sig 556.
Well under 200 bucks. Darn good thing, so far. Just a schochi bit tight on the eye placement for a good sight pic. Seeing as how I don't have much respect for these "gas guns" I figure it's good enough for a bit over 300 yards.
Wouldn't want to click the scope for shooting but the clicks while very light are seem accurate enough to suit me.
Turns out the 60 V-Max w/26.5 gr RL-15 when zero'd @ 100 puts the POI exactly on the top edge of the first hash down @ 200 and exactly on the second hash @ 300 yards.
The last several groups were under MOA averaging 0.7 MOA at 300.
Groups were left and right of dead center due to slight wind changes which is why I don't prefer to shoot light bullets with brick like bc at much distance.
Pretty sweet for local sage brush yotes tho.
I don't much go for the BDC reticle idea but with some practice it may be an option for reaching out a bit. Just a tho't.