U2 IP Forensic Science: Types of Guns and the Nature of Gunshot Wounds Essay

The most common cause of death in homicides is a gunshot wound. The caliber of a weapon and the distance from a gun to a victim determine the features of an injury caused by bullets, shell casing, or projectile. Therefore, forensic investigators should know the types of guns and, consequently, understand the nature of gunshot wounds.

The overall process of gun-making consists of several steps:

1. Forging
2. Casting
3. Machining
4. Stamping
5. Woodworking
6. Metal treatments
7. Assembly
8. Testing (Holloway, 2015).

Barrel making is a complex and difficult process. The first step in making the barrel is to cut the bar to a specific length. After that, a barrel maker places it in the drilling machine. To achieve a straight hole, the barrel steel must also be uniform in its consistency. At the tip of the drill there is a hole, out of which through the drill shank, oil is pumped. Then, the oil goes through the drilled hole in the barrel and, on its way, washes all the chips created by the drill. The barrel maker intentionally drills the hole diameter under the specific bore diameter for the particular caliber. Thus, caliber is the internal diameter of the barrel, or the diameter of the bullet it fires, which is usually represented in millimeters, or hundredths/thousandths of an inch (Holloway, 2015). After the drilling process, it might be brought up to the necessary size by reaming it. Like in the drilling process, the reamer is also flooded with oil. These are the first and main steps in barrel making. The next stages depend on the type of barrel – cut or buttoned ones. In the case with a buttoned barrel, the next step is rifling (Sandlin, 2015). Rifling is “a series of parallel spiral grooves cut the length of the bore of the barrel” (DiMaio & Dana, 2006, p. 121). Its purpose is to impart a spin to a bullet to make it more aerodynamically stable and, as a result, straighter on its way (Prahlow & Byard, 2013).

The basic parts of revolvers and semiautomatic pistols are to some extent similar, but there is a big difference. Revolvers contain a cylinder within which at once several bullets can be placed. After one bullet is fired from the revolver, to load it again the cylinder must be rotated in such a way that the next bullet should be in one line with the firing pin and the barrel (Prahlow & Byard, 2013). A semiautomatic handgun contains a magazine, which slides into the handgrip. To place a bullet into the chamber demands the slide mechanism, which is pulled back toward the handle. Inside the magazine, there is a spring, which moves bullets automatically into the firing chamber, and after that, the gun is ready to fire again.

It is necessary to understand the differences between bullets, shell casings, and projectiles. The bullet is a lead portion of the cartridge, and when the gun is fired, it leaves the end of the barrel. Shell casing is a spent portion made of a cartridge, which is discharged after the gun is fired. It remains in the revolver’s cylinder, or it can be ejected in the semiautomatic weapons. The projectile is a general term for everything that exits a weapon (Bucholtz, 2014). There are different classes of bullets, casings, and projectiles. For instance, classes of bullets can be identified by:

1. Manufacture – for example, Winchester.
2. Caliber – 45 ACP, 9 mm, 12 gauge.
3. Composition – steel, brass, copper (Bucholtz, 2014).

Shell casings differ from each other in size, shape, and materials. A shell casing can have different styles of heads, for instance:

1. Rimmed – denoted by the suffix R, and have a rim at the base, which is wider than the rest of the casing.
2. Semirimed – denoted by SR; the rim is wider than the casing body.
3. Rimless – have no suffix.
4. Rebated – denoted by RB, the rim is smaller than the casing body.
5. Belted – denoted by B; the metal belt (above the extraction groove) is almost the same diameter as the rim (Duguid, n.d.).

There are two main types of gunshot wounds: perforating and penetrating. The penetrating wound is when a “projectile has entered the body but not exited,” while the perforating wound means that a “projectile has passed completely through the body” (Prahlow & Byard, 2013, p. 487).

There are two more types of wounds: entrance and exit. Entrance wounds have a marginal abrasion. They are usually round or oval. An exit wound may be round, or “as a small or large laceration” (Bucholtz, 2014, p. 159). It should be noted that the size of the wound does not identify the entrance or the exit. The exit wound is characterized by the absence of a marginal abrasion.

Once the gun is fired, hot gases and burned and unburned gunpowder exit the muzzle. There are four ranges of muzzle-to-target distance:

1. Contact to near contact – the gun is firmly against the body, and on the body, the hot gases, among which is carbon monoxide, enter the tissue resulting in a bright-red muscle discoloration.
2. Close range – the distance from the muzzle and the body can be from “near contact to a couple of inches away” (Bucholtz, 2014, p. 162). Here, the gases can diffuse from the weapon muzzle, and there will be less tissue destruction. The marginal abrasion will be evident.
3. Medium range – usually extends from 12 inches to arm’s length from the muzzle. Since the distance is bigger than in the previous two cases, the gases and gunpowder can diffuse or burn. Still, some gunpowder can reach the skin and after burning leave powder tattooing. The closer the gun is to the skin, the brighter the tattooing.
4. Distant range – the end of the gun is far enough from the body so that neither the gases nor the gunpowder will reach the body, and it will only show the entrance wound with its marginal abrasion (Bucholtz, 2014, p. 164).

The typical kinds of evidence from a handgun that can be found at the crime scene are trace evidence (gunshot residue), and weapons and firearms evidence (guns, knives, cartridge shell casings, bullet holes, and wounds). Besides, the close photographic documentation of visible wounds is also very important.

To sum up, death rates from gunshot wounds considerably vary all over the world. Gunshot wound investigations demand close attention to the details and pieces of evidence. It also requires basic knowledge about the common types of guns and their parts. After collecting, the necessary information and evidence the manner of death might be determined.

References

Bucholtz, A. L. (2014). Death investigation: An introduction to forensic pathology for the nonscientist. Waltham, MA: Anderson Publishing.

DiMaio, V., & Dana, S. (2006). Handbook of forensic pathology (2^nd ed.). Boca Raton, FL: CRC Press.

Duguid, A. (n.d.). An introduction to collecting artillery shells and shell casings. Web.

Holloway, T. (2015). A guide to handgun cartridges: A reference for common calibers. Morrisville, NC: Lulu.com.

Prahlow, J. A., & Byard, R. W. (2013). Atlas of forensic pathology: For police, forensic scientists, attorneys, and death investigators. New York, NY: Springer Science & Business Media.

Sandlin, G. (2015). The making of a rifle barrel. Web.