Reason I ask is because I have a Monarch with BDC reticle mounted on a Rock River Arms predator pursuit and it is dead on to 600 yds using the bdc reticles with a 200 yard zero. Reason I am interested in the M223 Nikon is that it has a parallax adjustment knob which my monarch does not. Parallax is terrible beyond 100 yds, and I want to develop loads using the Ladder Test at 200 yds. But the elevation knob is marked with 55 gr bullets at a certain velocity and was wondering if I could use different grains zeroed at certain distances and still be able to use the bdc reticles with the m223 like I can with my Monarch? Thanks for your help.