A COMPARATIVE STUDY: DISPERSION PATTERN OF GUN SHOT RESIDUE OF STANDARD AND COUNTRY MADE FIREARMS AT DIFFERENT DISTANCES ON DIFFERENT SUBSTRATE

Abstract

The study on dispersion pattern of Gun Shot Residue has more potential to solve the forensic firearm cases. The dispersion pattern and the elemental composition of Gun Shot Residue plays a very crucial role in the Examination of firearm, estimation of range of fire, identification of bullet holes, identification of shooter, identification of calibre of firearm and identification of type of firearm whether the firearm used in crime was country made or standard firearm. This study was conducted to examine the dispersion pattern of Gun Shot Residue on different substrate by different calibre of country made and standard firearms. In this study, two types of calibre of standard and country made firearms was taken i.e., 7.65mm and .315”/8mm calibre. The ammunition of (khadki factory, Pune) were used for test firing. Two types of Substrates were used for firing test i.e., Paper and cotton cloth. This study needs to test fire from the .315”/8mm & 7.65mm calibre of country made and standard firearms at various close-range distance viz 4”, 8” and 12” on cloth and paper target to compare and calculate the dispersion pattern of GSR during the test firing. All test firing were performed in the firing range of ballistics division of CFSL/CBI/New Delhi. After the test firing, The Gun shot residue were carefully examined, Photographed, and collected for further analysis. The Gunshot residue on the target were characterized & analysed into three categories, First by Visual examination, second by Scanning electron microscope and third by using EDX Detector. In the first Step, the determination of firing distance was first observed on the basis of visual examination on the cotton cloth and the paper target at different distance fired by different calibre of standard and country made firearms, the dispersion pattern was somewhat irregular circle. To find out the dispersion pattern area of GSR, we can draw two circles, one near the bullet hole, where more deposition of GSR and another near the outer area, where more tattooing is observed. Now, by putting, the formula of area of circle i.e., (A = πr 2) dispersion pattern area of GSR was calculated and then prepare a database, which further help in determining the range of firing and calibre of country made and standard firearm. In the second step, the samples were analysed under Scanning electron microscope to observe the morphology of GSR particles, large variation in the morphology of GSR particles were observed when fired from different calibre of country made and standard firearm on different substrate. In the third step, the samples were run under EDX (Energy Dispersive X-Rays) detector to determine the elemental composition of GSR. Large variations were in the elemental composition of GSR fired from different range, different calibre and different substrate of country made and standard firearms. This study will be extremely useful for the forensic expert in easy disposal of the cases where range of firing is to ascertain.