I hunt mostly deep woods, sometimes open fields for the Mule Deer. On a centerfire I have never seen the need for an AO. Maybe extreme long range, but I seldom take that shot. The normal deer has an 14" to 18" kill zone, can't see that an AO would help that much. My shots ae usually very fast and quick, no time to fiddle around. On my 22LR match rifles, AO is needed. at 50 yards no AO means no good score. Talking 1/4" or less here. Deer hunting I have a lot more latitude for a kill shot.