Notes:
Shotguns
Classification according to the use
Sporting - single and double , choked
Gaffirs - Greener , Schneider & Remington
Military - non automatic , auto-loaded
Parts of shotgun :
smooth barrel
stock
butt
safety
trigger
magazine
muzzle
action bar
Parts of cartridge
A plastic (sometimes paper) case
Primer
Propellant
Wad
Shot
The characteristics of firearm wounds depend upon:
• Nature of the firearm, whether shotgun or rifle
• Shape and composition of the missiles
• Range (distance) of firing
• Part of the body struck (head or trunk)
• Direction of firing
The range of the shotgun
the spread of the pellets.
depends on the choke .
Rifle cartridge
case
primer
powder
bullet.
Wounding potential
Penetration injuries
Crushing injuries
Entry wound and exit wound
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.
The shotgun is a firearm with a smooth long barrel designed to usually fire multiple shots/pellets and to be fired from the shoulder. It is a non rifled gun which means it has medium velocity of the projectile.There are different types of shotguns . Viz. Ghaffir gun , sporting gun , choked sporting gun , military shotgun. Instead of a single projectile like in rifled guns , it has shots or pellets also called slugs of different sizes and numbers.
Short guns consist of a smooth barrel ,stock ,butt , safety, trigger , magazine , muzzle , action bar. The safety prevents misfire . The stock and butt helps to reduce the recoil . The shell explodes in the action bar which propels the pellets through the barrel. The length of the barrel helps the pellets to give them a straight course . The end of the barrel may have a tapering called choking.The choking increases the effective range of a shotgun by pushing the pellets together as they exit the muzzle and delaying their dispersal. Shotguns may have different types of choking,
The cartridge of the shot guns has a case which may be made of all plastic , all brass or mostly ( plastic with brass) . Older shot shells were made of brass and paper . The number of lead balls of the given bore diameter required to make up one pound weight is called gauge . Most of them are 12 gauge .Internal wads made up of plastic are found in recent shotguns shells . Internal wads separate between the powders and shot / slugs to keep them in place , and act as a piston to them.
Range of fire and characteristics of shot-gun injuries to the head: contact and non-contact range
When a high velocity bullet enters the skull it may cause the skull to burst open causing evisceration of the brain, this is known as a Kronlein shot.
In contact shot over a bony area like skulls or head cruciate , stellate , ragged lacerations are seen because of the extreme force of the block back phenomena. The gases expand beneath the skin and Lacerate the margins of the wound, as they exit through the original entry wound. The internal damage is diffuse type and no cavitation is appreciated. Often , linear tears are seen in contact wounds on the head. A large irregular hole is produced in the skull, with fissured fractures running from the margins. The entire contour of the head or face may be destroyed due to which often the original point of the muzzle is difficult to locate. A large exit may be produced with brain tissues blown to a certain distance. The muzzle on the nose or mouth doesn't produce an exit usually due to greater resistance of the hard palate. Spitting of the angle of the mouth can occur due to the blast.Large gaping tears of the scalp are present.
Close range shotgun wounds of the head are almost as mutilating as contact wounds because the pellets are still traveling in a single mass. Wads or plastic cups from cartridges may be found in the wound.
In distant shots , the shots usually spread and cause less severe damage. The pellets may not even penetrate the calvaria but orbits are still in risk.
Range of fire and characteristics of shot-gun injuries to the trunk: contact and non-contact range
Close contact injuries in the trunk make a cone with preserved entry .Exit wounds are usually not seen in shotgun wounds as the pellets quickly lose their kinetic energy after hitting the body. Exit wounds in a shotgun injury can only be seen in case of a contact shot.The pellets are lodged in the visceral structure .
Wound track and adjacent tissues appear cherry-red due to absorption of CO.As the muzzle of the shotgun moves further from the body, tattooing disappear and the diameter of the circular wound of entry increases in size until a point is reached where individual pellets begin to separate from the main mass.The spread increases and the kinetic energy decreases as the range increases and the wounding potential decreases. Multiple pellets can be observed in non contact range which are often very distant.
Rifles – the high-velocity firearms. The cartridge, bullet and velocity. The temporary cavity formation.
Rifles guns have high velocity bullets due to the spinning gyroscopic effect . They are used in long range targets usually . These are heavier but give a precise and accurate shot.
The cartridge contains a tube,with gun powders (propellent ), missile ( projectile ) on its top of the percussion cap fixed in its base. The tube is generally made up of brass with a flat base containing primer which is connected to combustion material . The propellant is closed with a projectile on it's top. The projectile is of various sizes.
Due to the transfer of the kinetic energy to the surrounding tissues , a temporary cavity or stretch is formed by the impact which later the tissue recoils and the cavitations disappear leaving the track of the bullet called permanent caviations.The temporary cavity formation can be imagined as a splash of water when a diver enter the water .The maximal size of the temporary cavity occurs several milliseconds after the bullet has passed through the tissue . This temporary cavity only exists for 5-10 msec from its rapid growth to collapse, but it undergoes a series of pulsations and contractions before it disappears.It can also cause the fracture of large bones and rupture of the vessels .Fluid filled , low dense and low elastic tissues like brain , heart , lungs will have larger temporary cavities than the elastic tissues like muscle .
Range of fire and characteristics of high-velocity-firearm wounds to the head and trunk.
HEAD
In the contact shot , The discharge containing flame, gases, powder smoke and metallic particles will be blown under pressure into the track taken by the bullet through the body, often leaving little evidence that one is dealing with a contact wound. There will be a punched out hole ( clean ) cut on the outer table and beveled on the inner table. Exit wounds on the inner table will also show a clean cut hole . the wound is larger than the entry wound due to deformity and tumbling of the bullet entering the skull.Tangential wound will make a keyhole appearance on the skull
In case of contact shot over forehead or mastoid (head) region where the bone is thick, the entry wound will be large and irregular, stellate or cruciform shaped having everted margins because of expansion of gas between the skull and scalp. Back spatter may be seen.
TRUNK
In the contact wounds of the trunk , stellate , cruciform entry wound usually does not occur because the gas is able to expand into the abdominal or chest cavity or soft tissue . in the abdomen , cavitation will be seen due to blast effect and there is no or little evidence of the burning ,singeing , blackening and tattooing .in some cases , muzzle impressions can be seen . muscles around the tract will be cherry red due to presence of the CO . In the deeper examination , signs like blackening , bnuring ,powder residues will be found .Exit wound is smaller than the entry wound due to elastic nature of the skin . the exit diameter increases as the range increases.the exit wound will no signs