G7 Ballistic Coefficient
Also: G7 BC
A ballistic coefficient referenced to the G7 drag model, which fits long boat-tail spitzers far better than the older G1 standard.
A ballistic coefficient only means something relative to the standard projectile it is compared against, and the G7 drag model uses a long, sleek, boat-tailed reference shape. That reference closely resembles a modern match bullet, so a G7 number stays stable across the velocity range and predicts drop and drift more reliably than a G1 figure for the same bullet.
The practical payoff shows up at distance, where the boat-tail bullets favored for long range no longer match the stubby G1 reference well. Because G7 is a closer fit, its form factor varies less with speed, and solvers fed a true G7 value tend to track real-world impacts more tightly past the transonic region.