Generally speaking, you want about an inch high with a flat top AR. What I use on two of mine is bushmaster 1/2 inch riser blocks, along with Leopold lever medium height weaver quick release rings. Gives you the height you need, along with the ability to remove the scope / rings and use them on another sporting type with weaver type bases(bolt action) rifle without being to high, as most sporting rifles have lower comb height then an AR.
Larry
