BC variability is not a synonymous term with drag variability in all aspects, assuming so can lead to invalid comparisons between bullets. Ballistic Coefficient is a single value used as a scaled reference to a standard drag curve to characterize the drag of a bullet.
Drag variability has many root sources and each can have varying degrees of contribution to the total drag variability. The main sources of drag variability are:
- Bullet shape and/or dimensions.
- Muzzle exit and/or wear state conditions of the bullet influenced by:
- Barrel dimensions, rifling form, and twist rate.
- Muzzle device (flash hider, brake, suppressor etc.).