Re: Actual vs. published bc
I think you will find Bryan Litz' BC's to be very accurate. I use his. But if he hasn't calculated one for a particular bullet, I use the manufacturer's BC as a starting place. Then I shoot the bullets and confirm drops at different ranges. Then I fudge the velocity and BC to get the closest curve for my load and rifle. To do this right, your info must accurate. Scope height, accurate zero, accurate groups and interpretation, accurate environmental conditions and the farther you test your drops, the better.
You will never know how much it has cost my generation to preserve your freedom. I hope you make good use of it.
~ John Quincy Adams