SCHAUM Final Project

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Forensic Identification: Firearms and Ballistics Kortney Schaum School of Education and Social Science, Saint Leo University CRJ 547: Forensic & Medicolegal Death Dr. Onalee Briley June 26, 2022

Forensic Identification: Firearms and Ballistics Over the past hundred years, ballistics has played an important role in courtroom proceedings. The topic of ballistics as a forensic technique, however, hasn't gone unchallenged or unscathed over the years. Even though the use of firearms is heavily emphasized in law enforcement, firearms as a whole have had just as much impact on the legal system as any other technological advance. The study of forensic ballistics deals with the analysis of evidence from firearms that may have been used in a crime. An analysis of ballistics focuses on motion, dynamics, angular movements, and the effects of projectiles (Crime Museum, 2018). Ballistic trauma is the result of a projectile entering the body. Bullets, birdshot, buckshot, and metal objects from an explosive device can be examples of these projectiles. Bullets can provide information regarding the type of gun used by the criminal, as well as whether the firearm has been used for other crimes. What is a Firearm? According to the Forensic Science Expert (2022), a firearm is any instrument designed to discharge or launch a projectile with the help of expanded gases of the main charge. Examples of firearms include rifles, shotguns, and handguns. Despite the fact that firearms have evolved over time, they still use projectiles such as bullets and shots through a barrel. The barrel, magazine, hand guard, trigger guard, grip, and trigger of a handgun are its main components (UNODC, n.d.). The magazine is the ammunition storage and feeding device of the firearm within. It is essential for a firearm to have those components which enable it to function properly and to be identified. A firearm's identification can be impacted if these components are changed, so their trade should also be regulated. One of the most important components of any firearm is the barrel. Explosive charges propel projectiles or bullets during their journey through barrels. A

firearm's receiver contains the parts used to operate it, including magazines that contain ammunition. As a result of changing the barrel of a firearm, bullets fired from the same weapon cannot be identified since the markings of the new barrel are different from the markings of the original barrel (UNODC, n.d.). Additionally, the new barrel may have a different serial number or no serial number, making it impossible to identify the firearm physically. The barrel, magazine, hand guard, trigger guard, grip, and trigger of a handgun are its main components. Types of Firearms There are many different types of firearms including smooth bore, rifled bore, manual/semi-automatic/automatic, handguns, shoulder guns, etc. These types can be broken down into two categories smooth bore firearms and rifled firearms (Shrestha et al., 2022). Also, there are country-made firearms, which are unusual projectiles found in developing countries. In the case of smooth-bored guns, cartridges that contain smaller metal pellets are used as projectiles (Forensic Science Expert, 2022) . In smooth bore guns, there is no groove inside the barrel and the inside is smooth. Examples of smooth bore firearms include shot guns, country- made firearms, and muskets. When looking at rifled firearms, there are spiral grooves inside a gun barrel that give the bullets a spinning motion (Forensic Science Expert, 2022) . Examples of rifled firearms include rifles, revolvers, pistols, machine guns, etc. According to NIST (2021), there are significant differences between the smooth bore firearm and the rifled firearm. The smooth-bored firearm, on the other hand, ejects the entire cartridge rather than just one projectile. The pellets in this cartridge are tightly packed and disperse as the cartridge moves toward the target. Wads also keep pressure and gas from diffusing into the pellets as the pellets travel. They separate the primer from the gunpowder, as well as provide separation between the primer and gunpowder. As a consequence, smooth-bore firearms cause wounds that also exhibit

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abrasions and contusions from projectiles, cartridges, and wads (NIST, 2021). Additionally, cardboard or plastic wads may be found in the wound tract. In addition to the wounds caused by guns, forensic experts will examine bullets, bullet fragments, cartridge cases, shot shell wadding, among other things. In the case of a firearm left at the scene, forensic experts will examine the four types of ballistics. Types of Ballistics According to Forensic Science Expert (2022), there are four types of ballistics including internal, transitional, external, and terminal ballistics. Internal ballistics is the first phase that involves the analysis of the propulsion and the flight of projectiles. This stage takes place during the point of firing the pin or striker to the exit of the bullet from the muzzle end of the barrel (The Ballistic Assistant, 2019). Various factors affect the performance of a cartridge, such as the powder, bullets, brass, and primer. The entire firearm is crucial to internal ballistics. In the internal ballistic field of study, chamber dimensions, rifling, twist rates, suppressors, and barrel harmonics can all have a significant impact on the bullet's external ballistics (BYJUS, 2022). If you compare a bullet fired from a rifle with one fired from a shotgun, the rifle bullet has more energy. The reason for this is that the energy of the bullet varies depending on the source. The propulsion of shotgun bullets and rifle bullets will be explained using internal ballistics. Under a microscope, forensic investigators examine fired bullets and casings under a microscope to find out if a certain firearm was used. The transitional ballistics, also known as intermediate ballistics, bridges the gap between internal and external ballistics. After a bullet has propagated, this process begins. In transitional ballistics, the projectile behavior from propulsion to the time of equalization of pressure is studied (BYJUS, 2022). When a bullet exits the muzzle, the pressure behind it does not dissipate

instantly. Due to aerodynamics and friction with the air, the pressures drop significantly for a short period of time, and the acceleration goes from positive to negative (The Ballistic Assistant, 2019). The external ballistics time period begins after the pressures have been equalized. There is still much to learn about transitional ballistics, as it is not fully accepted as a type of ballistic in some cases. External ballistics is the study of the projectile in flight and analyze the path (The Ballistics Assistant, 2019). This stage does not always refer to bullets, but can also include a sabot or a missile. Once a projectile comes out of the muzzle it should go along the axis of the barrel of the firearm and travel equal distances in an equal time interval (The Forensic Library, n.d.). There are several variables that are important to external ballistics, including projectile drag, atmospheric conditions, velocity, wind, projectile spin, and the projectile weight. Many individuals who take hunting and shooting seriously study the external ballistics seriously. These individuals try and predict the trajectory of the bullet prior to taking the shot. In forensic examination of external ballistics, they will use calculation and reconstruction of bullet trajectories. Forensic experts will also establish a maximum range of a given bullet. The last phase of ballistics, terminal ballistics begins once the projectile comes to an end of its journey. Forensic experts are concerned with the behavior and effects of a projectile once it hits and transfers its energy to the target (The Ballistic Assistant, 2019). Terminal ballistics might be called wound ballistics if the target is the human body. Various parts of the human body have different reactions to missiles of similar caliber and velocity, which is an important aspect of terminal ballistics (Sehgal & Mondal, n.d.). In the human body, the bullet dampens its way through having a small entry hole and an equally sized exit hole. But, in some cases, there is

not an exit hole due to the bullet staying in the body. Forensics examine terminal ballistics by trying to optimize the amount of energy that is transferred from the projectile to the target. Identification and Individualization of a Firearm Despite the identical make and model of firearms, no two firearms will produce the same distinctive marks when fired. A firearm's surface characteristics cannot be reproduced exactly in another firearm due to manufacturing processes, use, and abuse. Every firearms identification case must conduct a preliminary examination of the evidence to determine if there are any similarities in class characteristics and different individual characteristics (Forensic Science Expert, 2022). Characteristics that are common to a particular family or group of items can be defined as class characteristics. In terms of bullets fired from a firearm, a firearm's caliber and its rifling pattern are its class characteristics. A breech mark, firing pin impression, extractor mark, and an ejector mark, on the other hand, are examined for class similarities in cartridges and cartridge cases (Chinmayi, 2021). It is possible to see fine striations on the barrel from marks left behind using the bullet's lands and grooves. Class characteristics of bullets include caliber, number, and direction of grooves and landings, twist direction, and the width of grooves and landings. A bullet's movement creates a high level of pressure, which causes the bullet to hit the rifling. A fired bullet thus possesses both the land and groove characteristics (Chinmayi, 2021). Defining a weapon's caliber involves measuring the bore's diameter from point to point. This class character is also assigned to bullets when they are manufactured. In forensic comparison, forensic experts look at the identification number, certification mark, weight, diameter, and base design of the cartridge, as well as the color and shape of the bullet (Forensic Science Expert, 2022). Bullets fired from firearms have all these characteristics imprinted on them.

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An individual characteristic is a mark caused by an imperfection or irregularity in the tool's surface. In this case, random imperfections or irregularities appear as a result of the manufacturing process and/or corrosion or damage (Chinmayi, 2021). The imperfections are part of the tool's characteristics that make it stand out against other tools. A bullet's surface is marked with striae as a result of rifling. This is an identifying feature of a bullet. The various striations found on a bullet are landmarks, skid marks, and stripping marks (Chinmayi, 2021). Marks left by a bullet upon contact with the raised portion of a firearm's bore are called landmarks. During the firing of a revolver, a bullet leaves behind recognizable skid marks. It is also possible to see stripping marks on bullets discharged from loosely fitted barrels, often due to worn rifling. As a result of these striations, it is possible to directly identify the bore of the weapon by examining the lands and grooves. When comparing individual cartridge impressions forensic experts examine breech marks, firing pin marks, chamber marks, extractor marks, and ejector marks (Forensic Science Expert, 2022). Class characteristics are usually measurable characteristics restricted to a particular group of specimens. Individual characteristics, on the other hand, are patterns created by irregularities on a tool surface unique to that specimen. Through this analysis of bullet characteristics, such as class and individual features, one can identify the weapon that fired the bullet, thus narrowing down the perpetrator. Comparison Microscope In the past century, forensic ballistic comparisons have given investigators confidence that rifling marks on bullets and firearm tool marks on cartridge cases are conclusive evidence. Over the past hundred years, the comparison microscope has adapted and changed. To compare specimens side by side, experts use a comparison microscope with a single eyepiece and two microscopes connected. Forensic scientists use comparison microscopes to identify or deny

whether microscopic patterns have shared origins or not. Comparison microscopes are vitally used in forensic ballistics to compare fired bullets and cartridge cases (Forensic Analytical Crime Lab, 2022). In the normal operation of a gun, numerous marks are left on the projectile and the cartridge case. Scientists are able to determine if a specific projectile originated from an unidentified weapon by closely inspecting the weapon, the projectiles, and the cartridge cases. When recovered, fired bullets and cartridge cases are found at a scene, but no firearm is found, the make and model are determined (Forensic Analytical Crime Lab, 2022). It is possible to identify the firearm that could have fired the evidence by examining the bullets and cartridge cases and categorizing the markings by their class characteristics. In this way, possible leads for investigation can be identified. Range of Fire Spitz and Diaz (2020) indicate that firearms caused about 37,000 deaths in the United States in 2015. That same report stated that firearms were involved in 70% of the homicides during that same time period. Among the primary goals of forensic firearms are defining the path of a projectile, determining what tissues were injured, estimating the severity of injuries, and determining what additional studies are necessary (Pinto et al., 2015). In some shooting cases, the shooter may claim that they accidentally discharged the firearm or that it malfunctioned. In order to establish the details of the shooting, the firearm can be subjected to a variety of tests. In shooting a weapon, the trigger pressure refers to the amount of force required to pull the trigger. Some firearms with light trigger pulls may accidentally discharge themselves, and calculating the trigger pressure can give an indication of how likely it is that the trigger was pulled accidentally (Chinmayi, 2021). The user of some firearms can select either a normal trigger pull or a light trigger pull; therefore, it is also important to determine whether this feature is available and

which setting was chosen when using the firearm. The majority of gunshot homicides occur in young adults, while the majority of suicides occur in older individuals. Among the leading causes of injury-related deaths in adolescents, gunshot injuries are second only to automobile accidents in terms of death. Among the most vulnerable organs to bullet, injuries are friable solid organs like the liver and the brain (Pinto et al., 2019). The tissues in the body that are dense and loose, such as bone and subcutaneous fat, are more resistant to bullet injuries. When a case involves a firearm, and it is left at the scene, test firing of the gun with the type of ammunition is crucial. Determining the range of fire completely depends upon how much gunshot residue accumulates over the wound (Forensic Science Expert, 2022). For testing targets, it is recommended that fresh pigskin be used since gunpowder particles that hit the body at close range can cause superficial wounds. The projectile, along with the ejecta, emerges from the muzzle when the range of fire is examined. Among the ejecta are flames, projectiles, smoke, powder grains, metallic chips, and wads. Ejecta particles travel a distance from the muzzle based on several factors: the type of firearm (smooth bore/rifled bore), the type of ammunition (black powder/semi smokeless powder/smokeless powder), the type of target, the caliber of the firearm, and the length of the barrel (Forensic Science Expert, 2022). Forensic science pays excellent attention to gunshot residue over wounds in these cases. Generally, firearm injuries fall into three categories, including contact shot, close-range shot, and distance shot. At the moment of firing, the firearm's muzzle comes into direct contact with the victim's body, causing a contact wound. Typically, a close-range shot is one fired from a distance where gunpowder residue, primer particles, and small pieces of metal can be observed around the bullet hole (Spitz and Diaz, 2020). Distant shots are those fired from a distance that prevents gun smoke from reaching the target. Generally, the closer a firearm is to the target, the more concentrated the gunshot residue

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pattern will be, while shots fired from a greater distance will be more widespread. Scientists can estimate distances between the muzzle and target by carefully evaluating suspected/known weapons and evaluating known weapons range-of-fire tests. Conclusion Forensic firearm and ballistic identification are crucial in many cases of homicide, suicide, accidents, and more. In forensic ballistics, evidence from firearms can be analyzed to determine whether they were used in crimes. It is possible to discover several pieces of information through the examination of bullets fired at crime scenes. In addition to identifying what type of gun the criminal used, the bullets can also reveal if it was involved in another crime. Changes in the barrel, magazine, handguard, grip or trigger can affect the forensic identification of a firearm (UNODC, n.d.). When forensic investigators examine striations on a bullet from a gun barrel, expended ammunition can be traced back to a specific weapon by examining the unique striations on the bullet. Forensic experts continue to examine further by looking at the internal, transitional, external, and terminal ballistics. The forensic ballistics field is concerned with examining evidence derived from firearms that may have been used in a crime. When a bullet is fired from a gun, the bullet and cartridge case are left with microscopic marks, which can be examined under a comparison microscope (Forensic Analytical Crime Lab, 2022). Such marks are known as ballistic fingerprints. Forensic scientists continue to examine firearms by testing the range of fire which helps them determine if that specific firearm was used in the crime. In general, forensic firearm and ballistic identification has a significant role in a number of homicides, suicides, and shootings all around the world.

References BYJUS. (2022). Ballistics . https://byjus.com/physics/ballistics/ Chinmayi , G. (2021). Class and Individual Characteristics of Bullets . Forensic Yard. https://forensicyard.com/class-and-individual-characteristics-of-bullet/ Crime Museum. (2018). Ballistics. https://www.crimemuseum.org/crime-library/forensic-investigation/ballistics/ Forensic Analytical Crime Lab - San Francisco Bay Area, CA. (2022). https Forensic Criminalistics, Ballistics & Firearm Testing .://www.facrimelab.com/general- criminalistics/ Forensic Science Expert. (2022). Introduction to Forensic Ballistics . https://www.forensicscienceexpert.com/2019/12/introduction-to-forensic-ballistics.html Pinto, A., Russo, A., Reginelli, A., Iacobellis, F., Di Serafino, M., Giovine, S., & Romano, L. (2019). Gunshot wounds: Ballistics and imaging findings. Seminars in Ultrasound, CT and MRI , 40 (1), 25–35. https://doi.org/10.1053/j.sult.2018.10.018 NIST. (2021). Ballistics . https://www.nist.gov/ballistics Sehgal, V., & Mondal, M. (n.d.). Forensic Ballistics . Pathshala. https://epgp.inflibnet.ac.in/ Shrestha, R., Kanchan, T., & Krishan, K. (2022). Gunshot Wounds Forensic Pathology. National Library of Medicine .

Spitz, W.U. & Diaz, F.J. (Eds.). (2020). Spitz and fisher’s medicolegal investigation of death: Guidelines for the application of pathology to crime investigation (5th ed.). Charles C. Thomas The Ballistic Assistant. (2019). The Three Parts of Ballistics. http://www.theballisticassistant.com/the-three-parts-of-ballistics/ The Forensics Library. (n.d.). Firearms & Ballistics . https://aboutforensics.co.uk/firearms- ballistics/ UNODC. (n.d.). Firearms Module 2 Key Issues: Firearms Parts and Components . https://www.unodc.org/e4j/zh/firearms/module-2/key-issues/firearms-parts-and- components.html

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