One of the important issues, a firearm expert is often confronted, is to opine on the wounding capability of fired bullet at various ranges. It poses varied problems if it is a smooth bore homemade/improvised firearm designed to fire revolver, pistol or rifle cartridges. Such firearms are used to an appreciable extent in crimes in India and other developing countries. This is mainly because of stringent licensing policy for the possession of firearm in the country. The available ballistic tables are irrelevant and inapplicable obviously because bullets fired from smooth bore firearms are neither imparted spin nor do they achieve desired muzzle velocities. The need for estimation of trajectory parameters of bullets fired from smooth bore home made firearm was long felt. The present paper discusses the computation of a suitable ballistic table for evaluation of varied forensic problems on scientific bases. A bullet fired from a smooth bore home made/improvised firearm tumbles and continuously changes its front area resulting into varying values of ballistic coefficients throughout the flight. Therefore, instead of using standard values based on form factor and sectional density, an average ballistic coefficient for the entire flight for each bullet has been determined by adopting Cuming's approximation.As expected,the calculated ballistic coefficients of pistol, revolver and rifle bullets have been found to be far less compared to their documented values appearing in available ballistic tables. Like wise, their muzzle velocities have also been found to be comparatively far less than fired from corresponding standard rifled firearms. Their muzzle velocities are well within subsonic velocity. They have been found to be usually in the region of 500 ft/sec irrespective of the ammunition used whether high powered rifle cartridges or handgun cartridges. They also vary widely from one firearm to the other though designed to fire same calibred ammunition.Therefore, fifteen values of muzzle velocity ,for each bullet, ranging from 100 ft/sec to 800 ft/sec at intervals of 50 ft/sec have been chosen for computaion of trajectory parameters so that all probable muzzle velocities are included. Likewise fifteen possible ranges from 20 ft to 300 ft have been chosen with an interval of 20 ft. The solutions of normal equation of motion of Mcshane et al. have been adopted to determine the trajectory parameters of remaining velocity, time, angle of attack, and drop below line of fire etc, by using calculated modified ballistic coefficients and expected muzzle velocities. The data has been computed for bullets that are commonly used in smooth bore firearms in India. The computed data serves as ballistic table for evaluation of variety of trajectory related problems of forensic interest for all those bullets that are usually encountered in crimes involving smooth bore home made pistols/firearms. For relative assessment of wounding capability the table has been made comprehensive by including the modified ballistic coefficient, weight and kinetic energy data. A study of the table revealed that handgun bullets of .32, 9mm, .38,.45 calibre and rifle bullets of .303. .315, 7.62mm calibre having assumed muzzle velocity of 400 ft/sec attain maximum possible horizontal range of 200 ft , if the pistol/ firearm is kept at shoulder height of 4-5 ft from the ground and fired almost horizontally. Their respective energies at maximum range of 200 ft have been found to be far less than 58 ft lb signifying that none of the bullets is capable of causing disabling wound if 58 ft lb criterion is adopted. Many other significant forensic inferences that can be drawn from the study of the computed ballistic table have been discussed in the paper.

 

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