Firearm And Tool Mark Identification

In 1791, Congress ratified the Second Amendment to the United States Constitution allowing Americans the right to “bear arms”. Millions of private citizens now own or have access to some type of firearm. Once widely used in recreational and competitive sporting activities, they are now being used more for self-defense purposes and in criminal activities. Recent statistics show that “more Americans have died from guns—1,516,863—in the United States since 1968 than on the battlefields—1, 396,733—of all the wars in American History” ( Kristof, 2015). During the years of 2013 and 2014, thirty-three percent of gun related deaths were by homicide and that number is steadily increasing. More and more, criminals are using technologically advance …show more content…
According to the Association of Firearm and Tool Mark Identification, during the American Civil War, confederate General Stonewall Jackson was killed in the line of duty. The bullet taken from his body was compare to those used by Confederate soldiers, .67 caliber round ball shot, and those used by Union soldiers, .58 caliber conoidal shaped projectile. Based on the class characteristics (intentional or design features that are common to a particular group or family of items), it was determined that General Jackson died from a gunshot wound from a Confederate musket (AFTE, 2001). Today’s class characteristics are more sophisticated than those of yesterday, but unique markings, scratches, and dents within the instrument are still used for identification purposes. The first method discussed was class characteristics, which includes caliber and rifling (number/width of land and grooves, direction of twists). Caliber refers to the approximate internal diameter of the barrel or the projectile it fires. Rifling consists of grooves which are cut spirally, lengthwise down the inside of a barrel, and lands, which are raised areas between two grooves. The number of grooves and lands can vary from a low of two, to as many as twenty-three; however, they are equivalent in numbers. If there are 6 grooves, there are also 6 lands. The interaction of the projectile with the interior of the barrel …show more content…
When a bullet travels down the barrel, it follows the spiral grooves and develops and maintains a spin as it exits. Forensic examiners compare the impressions left behind with the firearm collected as evidence to determine if the bullet is from a particular weapon or a group of firearm manufacturers. The differences in rifling characteristics of manufacturers permit the examiner to determine the type of weapon that fired a projectile by measuring the width, number, and the direction of the twist found on the bullet. If results prove that the evidence bullet and test bullet have the same class characteristics, then it can be said there is a possibility that the evidence bullet could have been fired from the confiscated firearm. Further proof is needed to see if there is or is not a link between the items. Forensic scientists then examine individual characteristics of firearms to assure or negate this possibility. Many firearms are built to the same specifications, so there is very little variation in makes and models of the same type, but, individual characteristics provide unique attributes to firearms and tool marks. These markings are accidental, or unintentional attributes left on the object during the manufacturing process. Examiners view striations and impressed marks on bullets to help with identification because they have the potential to be