Ratio of the sectional density of a bullet to its coefficient of form. Represents the projectile's ability to overcome the resistance of the air in flight; a bullet with a high BC will overcome air resistance better than one with a low BC. More exactly: ratio of the product of drag coefficient (Cd) and reference area (A) to mass (m), giving CdA/m; also defined as the inverse of this quantity when used in other contexts; similarly, object weight (W) is sometimes used in place of object mass with the inverse definition, giving W/CdA.