looking foreward to your results faris, not a math whiz here but I do regularly shoot at ranges farther than average, my deer kills last year came at 503, 611, 781, 822 yards.
Going back through my records I only have 1 rifle that I have chrony'd 150 and 180 gr bullets through, its a lilja barreled 1/9 7mm STW, going by my velocities for those weights and the BC's scott posted for the bullet weights in my program for that rifle the 180/.613 BC surpasses the 150/.511 in retained velocity at 800 yards and has a foot more drop than the 150 at 1K.
My ? is if the formula's posted are correct why aren't all 180 gr 30 cal bullet BC's the same?
I know you lower your sd by making a bullet lighter, I also have a few friends shooting wildcat's alum. tipped .338 bullet which I think weighs 278 gr, on a 350 gr profile in some very large capacity 338's and those guys are reporting pretty spectacular results.
RR
It is important not to try to reduce the performance of all bullets to one mathematical formula. The SD of a 180 gr boattail hollowpoint is the same as a 180 gr round nose. Both are great bullets, but for different applications. the same goes for BC. The ogive of the bullet plays an extremely large role in the BC. The drag coefficient of a bullet is a function of the ogive given by the designer. Most of the new high BC bullets have very long ogives to help them you might say part the air and slip through it. It obviously works with bullet designs like the Bergers and the Wildcats.
What is missing in the equation still is the management of the distribution of mass in the bullet. SD won't be affected as long as the weight does not change, but BC with the same weight and the same bullet profile, but with different distribution of the mass of the bullet will be affected.
We are heading down this path. Not only do we want to change the mass of a given profile, but we also want to change the distribution of that mass.
Your friends who are shooting aluminum tipped bullets may by virtue of removing mass from the tip of the bullet be contributing to an increase in BC while lowering the SD
I am convinced that the only way to truly know the BC of a bullet is to shoot it and calculate the BC based on the chronograph results. Calculations from formulas can be close, but in this sport close only counts in hand grenades and horseshoes and maybe 155 rounds from 16000 meters. Too many variables.