Not only is improved instrumentation able to derive the exact drag curve for each bullet tested, but testing reveals that the drag function is related to more than just the bullet. Shooters take published load velocity numbers with a grain of salt; we accept that velocity will vary from gun to gun. We find that the same is true for BCs and drag functions. Perhaps the best summary is available on Hornady's web site where they discuss their 4-degree-of-freedom model and radar data. Bullets from the same lot behave differently when fired from different guns. We are still learning.
