TOPIC: Firearm Injuries II
Sub-topics:
· The shot-gun, a medium velocity firearm and a shoulder gun: its parts and their function, the smooth bore, and the parts of the cartridge
· Range of fire and characteristics of shot-gun injuries to the head: contact and non-contact range
· Range of fire and characteristics of shot-gun injuries to the trunk: contact and non-contact range
· Rifles – the high-velocity firearms. The cartridge, bullet and velocity. The temporary cavity formation.
· Range of fire and characteristics of high-velocity-firearm wounds to the head and trunk.
Notes for the topic: Shotguns are smooth bore firearm weapons, which can fire missiles or cartridges, which contain multiple small lead pellets at the same time. The range of fire is extremely important in shotgun wounds since there is a rapid decrease in velocity of the shotgun pellets whose shape is unfavorable ballistically. Where the barrel of the shotgun is in hard contact with the head, a large volume of gas also enters the cranium - the effect of which is one of massive destruction. The explosive effect disrupts the cranium and its contents, so that pieces of skull and brain tissue are spread over a wide area. Contact wounds involving the chest and abdomen are very similar to contact high-velocity rifle wounds in that there is massive outward expansion of the entire area by the gases entering the body so that the skin literally envelops the end of the weapon. The passage of a high-velocity missile through the body creates a path of destruction from the bullet and causes the formation of a temporary cavity. The pressures generated by the temporary cavity are quite capable of completely disintegrating organs and of causing fractures well away from the actual path of the bullet.
The shot-gun, a medium velocity firearm and a shoulder gun: its parts and their function, the smooth bore, and the parts of the cartridge
Shotguns are smooth bore firearm weapons, which can fire missiles or cartridges, which contain multiple small lead pellets at the same time.
Shoulder guns: A firearm that is normally fired while held in the hands and braced against or upon the shoulder
Parts of shotgun:
Muzzle: The muzzle is the very front end of the barrel where the projectiles exit. Choke: The muzzle end of your shotgun has a choke that helps control shot constriction. It works like the nozzle of a garden hose, controlling the spray of shot.
Barrel :The barrel is a long metal tube that provides a straight exit path for shot to travel.
Trigger: This is the lever you pull to initiate the firing sequence as they are pushed forward by expanding gases.
Cartridge of a Shotgun : Shotgun cartridge is the ammunition for smooth bore firearm, which can be loaded into the chamber of the shotgun and can discharge the pellets on being fired. The shotgun cartridge is made up of — cartridge case, gunpowder, wad and pellets.
Cartridge case:It is an elongated cylinder, made up of cardboard or special paper or plastic composition, length of which varies with type of shotgun. It has two ends. Flat closed end known as the base; this is metallic and has a central depressed area called percussion cap (primer cup), which accommodates the primer mixture (detonator) next to it within the case. The second flat end, which is the closed terminal end, and is comprised of a cardboard disk and holds the pellets under it.
Gunpowder: It is placed in the compartment immediately next to the detonator at the base of the cartridge and the pellets at the upper end.
Wad: It is a rounded disk of some thickness (usually a few millimetres) and made up of compressed paper, felt or plastic material, and it physically separates the gunpowder and pellets.
Pellets: These comprise multiple uniform spherical balls of lead. The cardboard disk and the wad help to keep these pellets as a compressed core in one mass within the cartridge case
The smooth bore: The barrel in a shotgun of any type is perfectly smooth on the inner aspect of its cylindrical wall, and this is the source of the term smooth bore firearm for a shotgun. Bore of a shotgun is the inner diameter of the barrel. Caliber of the shotgun is usually measured by the two methods: direct method and indirect method.
Range of fire and characteristics of shot-gun injuries to the head: contact and non-contact range
The range of fire is extremely important in shotgun wounds since there is a rapid decrease in velocity of the shotgun pellets whose shape is unfavorable ballistically. As distance increases, the shot also disperse so there are fewer that will strike the victim. The extent of tissue destruction is limited to the tissue that each individual pellet physically disrupts and shreds because temporary cavity formation does not play a role. At close range, however, the shotgun is the most formidable and lethal weapon of all the small arms.
Contact shotgun wounds of the head: When a shotgun is discharged into the head during a contact (loose or hard) or close range shot (up to about 15-30 cm or 6-12 inches), the pellets contained in the cartridge have not had time to spread, and they enter the body as a single mass. Where the barrel of the shotgun is in hard contact with the head, a large volume of gas also enters the cranium - the effect of which is one of massive destruction. The explosive effect disrupts the cranium and its contents, so that pieces of skull and brain tissue are spread over a wide area. Determining the point of contact requires meticulous gathering of skull fragments and attempting to reconstruct the skull and head, in order to find a hole, which will usually be heavily soot stained.
Intermediate and close-range wounds of the head are very nearly as severe as contact wounds since the pellets enter the head in a single bolus. Massively lacerated wounds may be seen, and the exit site is difficult to determine.
Contact shotgun wounds of the torso: Contact wounds involving the chest and abdomen are very similar to contact high-velocity rifle wounds in that there is massive outward expansion of the entire area by the gases entering the body so that the skin literally envelops the end of the weapon. This action often leaves a very detailed imprint of the muzzle of the weapon, including the unfired muzzle min a double-barreled weapon. An imprint of the sight may also be seen, even though it is an inch from the end of the weapon.
Rifles – the high-velocity firearms. The cartridge, bullet and velocity. The temporary cavity formation
A bullet traveling <1500 ft/ sec is considered low velocity, a bullet traveling 1500-2500 ft/ sec is classified as medium velocity, and one moving >2500 ft/ sec is considered high velocity. Rifles can produce completely devastating wounds while the damage from handgun bullets is essentially confined to the direct path of the bullet, whereas, centerfire rifle bullets can sometimes produce massive damage to structures, including skeletal fractures, without ever directly contacting them. The severity and extent of centerfire rifle wounds are not determined by the total amount of kinetic energy possessed by the bullet when it leaves the muzzle of the weapon but rather by the amount of that energy that is transferred to the tissue. Several factors operate in determining the amount of kinetic energy lost in the tissue. The passage of a high-velocity missile through the body creates a path of destruction from the bullet and causes the formation of a temporary cavity. The pressures generated by the temporary cavity are quite capable of completely disintegrating organs and of causing fractures well away from the actual path of the bullet.
•Range of fire and characteristics of high-velocity-firearm wounds to the head and trunk.
The most overwhelming wounds produced by these rifles are contact wounds to the head. The gases combined with temporary cavity formation cause massive, literally explosive, injuries of the head so that the point of entry may be very difficult to find. Characteristically, searing and blackening by soot are present at the entry. These wounds cause the head to be literally blown off.
Contact wounds of the trunk do not show the massive skin wounds associated with head wounds because the entire trunk is capable of rather massive expansion. With the exception of contact wounds directly over the heart or liver, contact wounds to the thorax and abdomen do not usually have significant injury from the entry of the gases into the body cavities. This expansion will cause the skin to envelop the muzzle of the weapon. The internal wounding, however, is just devastating as that to the head with massive disruption.
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