What he said. You can also alter your zero slightly to allow the dots to hit at 300/400yds. Play with JBM software and arrive at a zero that has roughly 2.2moa of drop at 300yds and 4.8 at 400 for the LRD at max power. You may need a zero of 190yds or maybe 220. I then tweak it at 300yd steel until it is "on". After that, i verify at 200 and 400 to see if POI is reasonably close. Usually works on Spitzers above 2,750fps.
Read this two or three times. If you can't figure it out go with the standard duplex.
