This would be a relatively minor thing to do, compared with other adventures in mind. it is also easy with excel yourself. Just create a table where you supply a specific bc for a specific velocity range.

However, a bc is directly related to the drag function: deacceleration=drag/bc*(other factors). Hence the concept of multiple bc is the same as using multiple drag functions for different velocity ranges - which is in fact a new drag function. The current receipe for max accuracy is for most situations: use G7 and Litz BC. The Lapua data are not validated, much is unknown about them. With BfX it is also easy to fit your own BC

The quest for maximum accuracy, however, I pursue by providing 6dof, later. 6dof will introduce yaw depending drag, amongst others.

Robert, 6DOF may be more work than you need to give yourself for accurate ballistic analysis. It would appear that only bullet manufacturers would have the aerodynamic data to use with 6dof programs. I have just re-read Litz's article on ballistic programs and he puts forward the argument that for small arms use then 3dof is best suited to the task. I compare the results I get using your current BfX function with Bryan's 3dof program and the results are almost exactly the same for all his G7 data. Not being very good at maths myself, I'm assuming your BfX functions are already using 3dof?

I quote part of Bryan's article below and would like your opinion on 3dof compared to what you would like to add to BfX with 6dof, if you could be so kind as to give it. Link

http://www.appliedballisticsllc.com/howprogramswork.html"If I were to write a ballistics program for small arms that’s intended to surpass the existing available packages, I would use a point mass solver (3-DOF numeric solver) for the following reasons:

1. Modern computers, even field deployable devices like palm pilots and cell phones have fast enough processors these days to solve a numerical solution in a reasonable amount of run time.

2. The program does not require you to store large tables (S, T and V functions) like the Siacci method.

3. You can make use of multiple standards (G1, G7, etc) depending on whichever one is best suited to the bullet you’re modeling. (Siacci also has this feature).

4. If you have access to a 6-DOF simulation, you can investigate trends like gyroscopic drift as a function of flight time for certain classes of projectiles, and then apply the trends as corrections to the point mass solution (Ref article: Extending Max Effective Range of Small Arms on this website). Applying the 6-DOF corrections won’t significantly affect computer run time.

I would avoid the Pejsa solution because of the difficulty of modeling bullet drag. Since the Pejsa method does not make use of any standard projectile drag curves, it’s up to the user to describe the drag of his own bullets. This requires establishing obscure coefficients and exponents for each bullet for several velocity bands. Large compromises are made when the projectile slows to transonic speeds and the drag curve is approximated with linear segments. The complexity of Mach dependant projectile drag belongs in the solution method, it should not be up to the shooter to figure out."

Ian