title: Estimating projectile perpendicular impact velocity on metal sheet targets from the shape of the target hole.
abstract: 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.
authors.affiliation: Toolmarks and Materials Laboratory, DIFS, Israel Police Headquarters, Jerusalem 91906, Israel. simanim@police.gov.il
authors.forename: Tsadok
authors.initials: T
authors.lastname: Tsach
authors.forename: Eliezer
authors.initials: E
authors.lastname: Landau
authors.forename: Yaron
authors.initials: Y
authors.lastname: Shor
authors.forename: Nikolai
authors.initials: N
authors.lastname: Volkov
authors.forename: Alan
authors.initials: A
authors.lastname: Chaikovsky