I want to sight in a rifle for a 300 yard zero. I only have access to a 200 yard range. I will use the JBM Trajectory program to create a drop chart. That chart wil give me a point of impact for 100 yards. I will adjust to get the rifle shooting to that point and then move to the 200 yard target without making any adjustments. I doubt that the actual impact point will be the same as the JBM prediction and therefore the 300 yard zero will not be accurate.
By using the actual 100 yard and 200 yard point of impacts I should have an accurate trajectory curve for my load and rifle set up. How can I use that curve to create a ballistically accurate chart with a 300 yard zero?
It has been suggested that I play with the B.C. numbers untill that produces the 100 and 200 yard actual impacts.