Determination of Calibre of Fired Bullets from its Distorted Base

Every day we hear or read the news of suicide, murder, kidnapping, extortion and shooting incidents. Criminals are using different types of firearms including country/improvised pistols to commit crimes. They may use to fire at human, non-human beings and solid materials. In many shooting cases, Trigonometry and Geometry often provide the mathematical bases for the solutions. It is quite common to find bullets at place of shooting occurrence during the course of crime scene investigation. For the purpose of reconstructing a shooting scene, Crime scene manager or ballistic expert may be able to identify the source of each bullet traced. The bullets recovered at shooting incidents are generally distorted and/or fragmented, hence determination of calibre is very difficult. The distorted bullet base take a normally oval shape. However, shape of bullets can vary considerably from bullet to bullet. In this paper authors have estimated the calibre of bullet by measuring the long and short axes of the oval shaped base of bullet. In present study a mathematical calculation for 9mm,.32�,.380��,.303��, 5.56x45mm, 7.62x39mm and 7.62x51mm bullets have been scientifically elaborated.