The BC's I gave you were measured directly by test firing, they're not related to Hornadys advertised numbers. If you're interested in how my BC's are measured, you can read about it here:
I've got a few comments about your approach. Again, no offense intended here...
It seems like you're trying to use your drop data to come up with a MV and maybe a BC. This is not a good approach unless you've verified that your scope adjustments are true
. For example, you say you need 8.75 MOA at 500 yards. What if your scope doesn't move perfectly as you think it does? What if your crosshairs actually move 9.12 MOA or 8.64 MOA when you have 8.75 MOA dialed on? This is more common than you might think. Also, did you measure the range to be exactly 500 yards, or is that just what it says on the sign? What I'm saying is that if you try to 'back-track' to find a missing variable in a ballistic equation, you have to be absolutely certain of all the other variables. Any uncertainty you have in atmospherics, range, BC, MV, scope clicks, or anything else will translate into uncertainty in the variable you're trying to identify.
Hope this helps. I'll be happy to discuss any of this further with you.