Thread: Changing ballistic info to match "real" drop.

After having done some set up with a new load for my 7mmRM and entering all of the relevant information into 2 different ballistic calculators (which both came up with the same trajectory data) I have found a difference in the actual drop (zeroed at 109 yards and tested at 440 yards) and the correction provided by the calculators.
It is shooting 3" high at 440 yards with the recommended dial up of 6.7 MOA.
I have only used one chronograph to check MV and I am relying on Noslers BC data from their web site.
My question is, what is the best way to change the calculation to match the actual drop?
Change the MV? Change the BC? or is there something I am missing?