File under useful information:
http://www.brownells.com/.aspx/lid=13093/guntechdetail/Sight_Correction_CalculatorFormula
Amount of Error X Sight Radius / Distance to Target = Sight Correction Needed
If you are shooting low, you would replace your front sight with a lower sight, and conversely, if you were shooting high, then you would replace your front sight with a higher sight. Add or subtract the number of thousandths needed to the actual height of your sight and you will have the correct height of the replacement sight.
