Mike,
Steve may get to this before I do, but what is your BP set for (magnification) to use the BP from the factory? The 3-12 is set to be used at 12x.
What is the elevation and approx temp. you will be hunting at?
What is the BC of your bullet?
Steve is better with Exbal than I am, but one of us will get the data to you ASAP.
When do you leave for your hunt?