Ballistic coefficient is not an absolute, independent value. It's an index of how a specific bullet's flight compares to the much-studied, thoroughly documented flight of a standard artillery test projectile -- usually the G-1 -- and that standard's ballistics tables -- Ingalls' or Siacci's tables, for example. I'm still disappointed from learning, years ago, that the ballistic coefficient is NOT (as I'd so long assumed) an index of how the bullet flies in air in comparison to how it would fly in a vacuum.
� No other projectile flies exactly like the standard test projectile at all points along its flight or at different velocities (so its ballistic coefficient is therefore different at different points and velocities, even when its muzzle velocity is exactly the same as the standard test projectile's muzzle velocity).
� No bullet's ballistic coefficient based on one standard test projectile describes how the bullet flies compared to the way that another standard test projectile flies. IOW, Bullet A's BC relative to the G-1 projectile's down-range behavior doesn't relate its flight to the flight of another tested standard projectile.
