Bullet Comparison And Analysis : Firearms And Tool Marks Division Of Most Forensic Science Laboratories

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Bullet Comparison and Analysis The firearms and tool marks division of most forensic science laboratories have several tasks they may have to perform on items of evidence that come to them; this ranges from testing functionality of a weapon, restoring serial numbers, finding and comparing marks left from different tools at a crime scene, and comparing and analyzing bullets and casings. To be able to perform a bullet comparison, one needs to be able to distinguish several base class characteristics, and then look for individualizing characteristics on the bullet. Once examined, the bullet will fall into one of four categories for the report writing. To ensure the accuracy of any examination performed, the laboratory should have set quality…show more content…
The examiner should also document the condition of the packaging and of the evidence received. The first step of the actual comparison, is determining the general rifling characteristics, or the class characteristics. Most fired projectiles will be able to tell an examiner the caliber of the barrel, the number and dimensions of the lands and grooves, and the direction of the twist of the rifling (“A Simplified Guide,” 2013). The caliber of the barrel of the gun is the “diameter of the bore of a rifled firearm,” usually measured in “hundredths of an inch or millimeters” (Saferstein, 2015). The number of lands and grooves can vary from manufacturer to manufacturer. By counting the lands and grooves, and measuring the width of the impressions, the examiner can narrow down the range of firearms to a specific class of firearm. The direction of the twist, whether it be counterclockwise (left) or clockwise (right), can also help narrow down the range of firearms. The condition of the bullet can limit the examiner’s ability to determine some of the class characteristics. If a bullet is to be compared further, the examiner needs to have something to compare it to. A known source will have to be brought in and test fired in a

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