zunrj5 - thanks, thats just what i was looking for. since ill have an A2 front sight block, ill probably use a riser too. I was considering using a leupold LR M3, since i have one on a bolt gun and im comfortable using a mildot. However, I want something without external knobs. So Im down to either an acog or the burris, maybe a few others. having never owned one, they seem like a good deal. ive read a few reviews of the fullfield w/bplex mounted on m1a's and they were all positive. with 7.62 nato ammo, the lower hash mark is at about the 600yd mark.