Scott, EJ you are both correct in that BC is in practice of little use when you are out shooting. You could argue that a high BC bullet with the same precision as a low BC bullet may give better accuracy due to the lower cross wind drift and the slightly flatter trajectory but there are plenty of other factors which will have more affect than BC. You are only really going to use BC when you are trying to calculate trajectories which of course is what it was invented for. The main use for trajectory calculations is in fire control computers and I don't know of many rifle shooters who use one of those while shooting.
But, even for trajectory calculation, BC has limitations in that, unless your bullet happens to be exactly the same shape as the reference projectile, you will need multiple BC values as no two shapes will have the same Cd/ Mach number drag curve shape. Over limited ranges and speed regimes this will not be a problem for most people as the accuracy of the results will be sufficient for many purposes, but as ranges increase it will become a problem. This is why, in the large calibre artillery ballistics world, BCs have not been used for about the last 50 years. It was getting to the point that you needed almost as many BC values for a trajectory as points in a specialised Cd/Mach number curve produced specifically for the shell in question. The widespread use of computers made the calculation of trajectories much quicker and easier. Also, using a Cd/Mach number curve, along with the shell weight and reference diameter, meant it is easier to see the effects of each individual parameter on the trajectory making it easier to produce error budgets. And if you are using a modified point mass model (used in most fire control systems) as opposed to a point mass model you are going to need a whole lot more input than just a simple BC or Cd/Mach number curve.
The down side with using Cd/Mach number curves is that you need a different one for each bullet/shell design. You may also need different curves for the same bullet/shell design fired from different guns or even for the same bullet/shell design fired from the same gun but with the bullet/shell made in different countries.
You should remember that the BC idea was created to simplify the calculation of trajectories in the days before computers.
But, even for trajectory calculation, BC has limitations in that, unless your bullet happens to be exactly the same shape as the reference projectile, you will need multiple BC values as no two shapes will have the same Cd/ Mach number drag curve shape. Over limited ranges and speed regimes this will not be a problem for most people as the accuracy of the results will be sufficient for many purposes, but as ranges increase it will become a problem. This is why, in the large calibre artillery ballistics world, BCs have not been used for about the last 50 years. It was getting to the point that you needed almost as many BC values for a trajectory as points in a specialised Cd/Mach number curve produced specifically for the shell in question. The widespread use of computers made the calculation of trajectories much quicker and easier. Also, using a Cd/Mach number curve, along with the shell weight and reference diameter, meant it is easier to see the effects of each individual parameter on the trajectory making it easier to produce error budgets. And if you are using a modified point mass model (used in most fire control systems) as opposed to a point mass model you are going to need a whole lot more input than just a simple BC or Cd/Mach number curve.
The down side with using Cd/Mach number curves is that you need a different one for each bullet/shell design. You may also need different curves for the same bullet/shell design fired from different guns or even for the same bullet/shell design fired from the same gun but with the bullet/shell made in different countries.
You should remember that the BC idea was created to simplify the calculation of trajectories in the days before computers.
