Analyzing The Impressions Left On The Bullet Is Call Ballistic Fingerprinting

943 Words Jun 23rd, 2015 4 Pages
Most modern firearms are rifled with the exception of the shotgun. The process of rifling the barrel creates unique patterns. These patterns are called tool mark impressions. The forensic technique of analyzing the impressions left on the bullet is call ballistic fingerprinting. There are two types of strations, class characteristics and individual characteristics. Class characteristics are shared by on type of gun and manufacture, for example a colt peacemaker has 6 lands and grooves left-hand twist. The individual characteristics are specific to the individual gun, for example any imperfections of the lands and grooves caused by the tool 's use in the rifling process or normal wear of the bore.
There are many types of barrels and barrel making methods. The methods of rifling a barrel include Broach, Button, Hammer Forging, Single Point, and Flow Forming. The most common is Button rifling. Button rifling uses a metal rod with a head or button that has the rifle pattern in the head. The metal rod is pulled through the barrel blank. The button’s pattern is compressed into the barrel as it travels through the barrel blank. This drawing of the button leaves liner scraps along the barrel. (Doyle) The scraps left behind by the rifling process are toolmark impressions. These tool mark impressions are unique to each barrel. When a bullet is fired through the barrel the tool marks impressions are left on the bullet as striations. These striations can be microscopy compared and…

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