How to Calculate a Bullet's Trajectory | Sciencing Nov 03, 2020 · Here (C) represents the drag coefficient of the bullet (you can find out for a specific bullet, or use C = 0.295 as a general figure), ρ is the air density (about 1.2 kg/cubic meter at normal pressure and temperature), (A) is the cross-sectional area of a bullet (you can work this out for a specific bullet or just use A = 4.8 × 10 −5 m 2, the value for a .308 caliber) and (v) is …