Each of the following mach-drag curves are available in Ballis-tec. Notice the extreme variation in drag coefficient among models.

While the G1 is typically considered the standard model, I have found that it produces too generous an estimate of velocity and subsequently, trajectory. In fact, all the G* models produce similar results.

Field conditions have been best approximated or simulated using the Spitzer drag coefficient in my experience. This model follows the type 'B' projectile ogive, shape, and form factor (cf. Hatcher's Notebook).

Trajectory is a function of numerous factors. Primarily, it is a function of velocity and the drag coefficient for the projectile being modeled. Using the Iterative Heun method -- a second order predictor-corrector technique-- the following factors are taken into account:

1. Muzzle velocity
2. Ballistic Coefficient
3. Downrange wind speed
4. Cross-wind speed

Stored in Parameters file:

5. Height of sight above bore
6. Initial gun elevation angle
7. Ratio air density to standard density
8. Air temperature
9. Standard atmospheric conditions version (ICAO or Standard Metro)

The factors specified in the parameters file can be edited by the user. However, when the user specifies ICAO or Standard Metro (required), item 7 is cross-referenced with the accepted standard within Ballis-tec.

In my experience, the factor that primarily influences velocity changes over distance/time --and subsequently your exterior ballistics trajectory curve-- is the drag coefficient table.