4. Shotguns
- The smooth-bore weapon consists of a metal barrel
which has parallel sides โdouble barreledโ.
- They usually fire a large number of small
spherical lead shot.
- A shot gun is designed for use up to 30 โ 50 m.
- Common sizes 19mm, 11mm.
- Ammunition consists of cartridge (metal base
containing a central firing cap supporting plastic
or cardboard tube). Inside the cartridge there is a
wad of paper & cardboard, with a mass of lead
pellets.
6. Rifled Weapons
- It differs from the shotgun:
2) They fire one projectile at a time.
3) There barrel has a spiral groove (bore).
4) Most of them have a mechanism for bringing a
new round into the breech
7. Rifled Weapons
Examples:
-- Automatic Pistol: self-loading weapon, where
shells are put into firing position by a gas operated
delivery system.
-- Revolver: bullets are brought into position via a
rotating cylinder
-- Rifle: a long barreled sporting or military weapon
8. Rifled Weapons
- The ammunition comes in many sizes.
- Itโs a closed metal cylinder carrying firing cap &
a powder.
- When striking the cap the powder burns rapidly
producing huge volume of gas that propels the
bullet with velocity varying from hundreds to
thousands of meters per second.
9. Mechanism of Injury
- As missiles traverse the body it causes injury by
transferring some of itโs available energy
- Severity of damage is proportional to amount of
kinetic energy & the density of the involved tissue
- KE = ยฝ M * V^2
10. Entrance Wounds
1. Shotguns:
- The mass of shot leaves the weapon initially as a
solid mass, which progressively diverges from
the weapon.
Contact Wounds (touching the skin)
- When a weapon is fired, the bullet, hot gases
from exploding gun powder & metal fragments
from the bullet & the gun barrel are propelled out
of the muzzle at the same time.
- The hot gases & metal fragments are blasted into
the body at the same time as bullet.
11. Contact Wounds cont.
- Round or oval central defect with an โabrasion collarโ
(where the bullet has abraded the skin surface as it
passes through it). The size of the defect is comparable
to the size of the muzzle opening or bore of
the weapon.
- โPink/redโ staining of the skin (due to carbon
monoxide laden gases producing
carboxyhaemoglobin)
- Gun powder blackening of the wound edges &
surrounding skin (from soot & unburned propellant
gases).
-Circular bruise over the skin due to muzzle impact.
12. Contact Wounds cont.
Summery
-Wounds are circular
-There may be muzzle mark
-There may be a slight local burning to the skin & hair
-Redness from CO gases
14. Near Discharge
- Within few cm of surface
-Large central defect with โstipplingโ or โtattooingโ
( small, dry, reddish abrasions caused by unburned
powder & small metal fragments striking the skin)
- Smoke soiling
tattooing
- Lack of muzzle mark
Intermediate Range
15. Intermediate Range
-Within 20 cm to 1 m.
- Diminishing of the smoke soiling but powder
tattooing persist
- Burning will be present
- The rim of the wound is irregular forming what is
called โrat-holeโ.
17. Long Range (2-3m)
-Satellite pellet holes will be seen around the
central wound, which diminishes in size as the
range increases.
- the spread of shot in centimeters equal two to
three times the range in meters.
e.g. if the wound pattern is 20 cm across the
discharge was roughly 7 โ 10 m so couldnโt be a
suicide.
18. Long Range ( 20 โ 30 m)
-Abrasion collar
-No smoke soiling, burning or powder tattooing.
-Tissue displacement.
-Rarely fatal.
19. Differences between shotgun &
rifles in entrance wound
Rifled weapons:
- show increased amount of tissue destruction due to the
high velocities involved.
-Usually have an entrance and exit wound unless bullet
has struck a bony area such as the skull.
-Estimation of firing range is more difficult than with
shotgun weapons, but in general , contact wounds show
similar features of powder stippling, blackening,
burning, tissue disruption, & carboxyhaemoglobin
formation.
20. Exit wound
-Shotguns: Rarely produce exit wound because they
traverse the body, but if happened it may cause a
huge ragged aperture wound.
-Rifled weapons:
--Exit wound is usually everted with split flaps.
--No burning, smoke or powder soiling.
--if the bullet flattened or has destruct some bone
internally, exit wound may be more irregular and
sometimes very large in size.
21. Exit wound
Exit Wound
with split flaps
Entrance Wound
23. Accident, Suicide, or
Murder
-Suicides must show wounds which range within the
arms reach unless some devices is present to reach the
trigger.
-Suicides shoot themselves in sites of election which
include the mouth, the front of the neck, the forehead,
or the front of the chest.
-Discharge into the entrance wound are usually on the
side of the dominant hand, but this is not absolute.
-People almost never shot themselves in the eye or
abdomen & naturally not in inaccessible sites such as
the back.
-Women rarely commit suicide with guns & rarely
involved in firearm accidents.
24. Accident, Suicide, or
Murder
-โA shot woman is a murdered woman until proved
otherwiseโ.
-Multiple firearm wounds suggest homicide, but this is
by no means inevitable.
-Itโs unwise to state that a gunshot wound must have
been immediately fatal, unless destruction of brain
stem or heart or transection of the aorta has occurred.
-There are many instances of gross brain damage,
especially in the cerebrum, bring followed by
prolonged purposeful activity.
-In suicide weapon must be present, though it may be
at a distance from the body.
25. Doctors duty in firearm
injuries & deaths
-Any missile, foreign body such as wads and any
skin removed from the margin of a repaired
firearm wound should be carefully preserved for
the police.
-The skin in post-mortem examination around
the entrance wound should be removed & kept
without formalin, but refrigerated if necessary,
for forensic tests for powder residue.
-In many countries firearm injuries must be
reported to the police even if not fatal.
