Estimating projectile perpendicular impact velocity on metal sheet targets from the shape of the target hole.

摘要

The correlation between bullet hole shapes in metal and projectile impact velocity was examined. A series of shots were fired from an M-16A1 assault rifle of 5.56 mm caliber toward a 1-mm thick metal target. All shots were fired at a perpendicular angle to the metal sheets, and the velocity was measured just before the projectile hit the target. Velocities ranged between 400 and 900 m/sec. From the replica of the shooting hole, a perpendicular plane was created, showing the symmetrical properties of the hole. The best mathematical equation describing the shape of the entrance hole was the exponential function in the form: Y x = A + Be kx. The empirical equation of the hole defined using the regression method is: Y x,V = 8.268/V 0.578018 e(0.584x/V0.005). This equation describes the general shape of shooting holes created by velocities ranging from 440 to 750 m/sec. From this equation, one can estimate the bullet velocity when it hits the target.