Smooth bore home made firearms and mismatched rifled firearms( improvised /imitation) are very frequently encountered in criminal cases. The main evidential value they offer, relates to their linkage through fired cartridges only. The possibility of identifying bullets fired from smooth bore home-made firearms have been left unexplored for seemingly unattainable results due to a very large  variation in shape, size, construction (form) and mechanism. The mismatched rifled firearms may or may not imprint repetitive rifling marks. Thus the linkage of the bullet with smooth bore and mismatched rifled firearms had usually been looked upon as insolvable problem resulting into ignoring the most vital evidentiary value of projectile evidence.

          A large volume of  experimental work involving about thousand firearms has been carried out to study the possibility of identifying bullets fired from smooth bore and mismatched rifled barrels.The design and performance of non standard firearms have been studied for classification of firearms and new nomenclatures introduced such as  under/over/mixed bore sized  firearm,  true cylinder/tapered  barrel, aligned/misaligned  chamber  etc.The striations caused by different type of non standard (smooth bore/rifled)barrels have been studied. The study of nature of marks coupled with plausible consideration of movement of bullet inside smooth bore/mismatched rifled barrel of varying dimensions has revealed the necessity of adopting identification procedure unlike those adopted for regular rifled firearms. For achieving fool proof bullet-firearm linkage, new techniques for obtaining test marks have been evolved and identification procedures modified for all possible bullet-bore combinations.

 

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