Custom Drag Model
Also: CDM · Custom Curve
A bullet-specific drag curve measured from radar data, more precise than fitting a projectile to a single G1 or G7 coefficient.
A custom drag model is a drag model built for one specific bullet, describing how its drag coefficient changes across the full range of velocities it will fly through. Instead of compressing a projectile’s behavior into a single ballistic coefficient referenced to a standard shape, a custom model uses the bullet’s own measured curve point by point. Manufacturers generate these curves from doppler radar tracking, which records true velocity decay over distance.
The advantage shows up at long range and through the transonic region, where a single coefficient can misrepresent how drag actually evolves. A custom drag model feeds a ballistic solver more faithful inputs than even a well-chosen G7 ballistic coefficient, tightening the agreement between predicted and observed drop. Several solver platforms now publish these curves for popular match bullets, and shooters select them in place of a plain BC for the most demanding firing solutions.