• indiscriminate use of sophisticated firearms

are rampant across world

• high frequency shooting cases necessitated
question pertinent to type of fire arm used,
caliber of bullet, number of bullets fired, the
angle of impact, position of shooter, direction
and range of firing, bullet holes, use of firearm
in a previous crime etc
• study of bullets and firearms - ballistics
• forensic ballistics refers- systematic study of
firearms and ammunition used in commission
of crime, for the purpose of investigation and
identification
• Classification of firearms and ammunition
• Firearm – weapon capable firing a projectile
using confined explosive
• modern firearm are classified – Long guns,
hand guns
1. Shot gun-
• acquires its name because they can fire pellets
or slug
• requires use of both hands accurate firing
• may be single or double barrel which may be
side by side or one over the other
• barrels have varied bore diameters, and
designated by a number and gauge or bore
• barrel are often narrowed to reduce diameter
of barrel near muzzle–to control dispel of
shot charge and thus to increase effective
range
• two ends of barrel of shotgun are called
breech and muzzle end
• breech end known-chamber end, which
special cavity to house a cartridge, - carries
extraction and ejection mechanism
• long barrel and characterized by their calibers
• barrels are grooved which are cut in form of
spirals from inside bore
• number of grooves in rifle varies
• different actions – most common are blot
action and semi automatic action
• rifled handgun which has a revolving cylinder
that could be loaded with several cartridges
and fired in rapid succession
• on pressing trigger cylinder rotates bringing
one of chambers inline with barrel for firing
• sizes vary – revolvers have short barrel which
are very effective in short range
• semi-automatic or fully automatic
PISTOLS
 PISTOLS
• short barrelled rifle arms which can be fired by
one hand
• ‘Colt’ and ‘Smith and Wesson’ are examples
• semi automatic or self loaded in which pull of
trigger is fired
• in addition to them, machine guns and variety
of military artillery do exist
• material fired, scattered, dropped or
detonated from any weapon
• FS-ammunition means cartridges composed of
shells, propellants, primer and projectiles
commonly used in firearms
 1. Cartridge case - is envelope of cartridge
known as shell or empty after its contents are
discharged - made of brass for rifle, pistol,
revolver, for shotguns paper or plastic with a
metal head and is more often called a ‘shell
• cartridge case holds bullet at neck, propellant
charge inside, and primer in its base
• outer circumference base of cartridge case
normally has a groove and rim to assist in
extraction from weapon after firing
• rimed cartridge helps in positing cartridge in
chamber and facilitates extraction
• rimless cartridges used in pistol and other
automatic and semiautomatic firearms
• primer composition is located in rim itself
 2. Primer and Primer cap -
•Primer- chemical and/or device responsible for
initiating propellant combustion that will push
projectiles out of gun barrel
•primers contains compounds of lead antimony,
barium
•primer cap contains primer mixture which get
sandwiched between anvil firing pin
• when firing pin strikes on primer cap with a
force it give rise to hot piercing flame which
initiates main charge
• quality of primer caps determines quality of
ammunition
 3. Propellant – to propel bullet or shot charge
through barrel and then through air, a
certain force is necessary – this force is
provided by power charge
•power charged get ignited through primer and
converts into gas at a very rapid rate
•generated gas under compression, develops
pressure on cartridge finally forces out of barrel
propelling projectile
• 4. Wads – used in cartridge basically to keep
propellant and short charge in their
respective position
• wads seal barrel to prevent escapes gases and
consequently their respective reduction in
velocity
 5. Projectiles – an object propelled through
air designed to be fired from a firearm by
exertion of a force
•commonly refers to a ranged weapon
• depending upon type of firearms projectiles
are used
• shotgun projectile consist of small lead balls or
pellets
• rifles, revolvers, pistols projectiles consist of
single bullet which fits the bore size
• bullets are made – lead, alloyed with tin or
antimony
• high velocity bullets have jackets made of
copper, cupronickel or steel
• bullets various sizes and forms – streamlined,
boat failed, or with flat base, Nose may- flat,
round or pencil, Size – short, medium, long
MECHANISM OF FIRING
 MECHANISM OF FIRING
• when a person pulls trigger of firearm, it
release hammer with a considerable force and
firing pin of firearm hits base of cartridge
igniting primer powder mixture
• tiny explosion of primer powder mixture on
anvil delivers a spark through a flash hole to
main gunpowder supply
 MECHANISM OF FIRING
• Anvil - internal metal component in a boxer
primer muster against which priming mixture
is crushed by firing pin blow
 MECHANISM OF FIRING
• main gunpowder supply ignites and
expression of explosion pushes bullet from
casing and into barrel of firearm
• amount of gunpowder and mass of projectile
in a cartridge determines speed of bullet
• bullet follows land and grooves pattern of
barrel and begin its spiral before it leaves
barrel
 Identification of Weapon and
Ammunition
• forensic ballistics asserts that firearm which is
manufactured factory has unique pattern
• firearm manufactured by a manufacturer will
bear certain markings for purpose of
identification such as serial number, makers
name’, calibre, number of lands and grooves
 Identification of Weapons and
Ammunition
• markings are stated as class characteristics
which enables in identifying owner
• in addition to it accidental marks also enable
in identifying firearm
• when a gun is fired the accidental marks that
can be visible are:
 Identification of Weapons and
Ammunition
1. Breech Block Marks:
•when bullet leaves its cartridge with such a
force that it pushes empty cartridge against
barrel’s breechblock which leaves a distinctive
impressions on cartridge casing known as
breechblock marks
•markings are unique to firearms and can be
matched - if cast-off cartridge casing are found
 Identification of Weapons and
Ammunition
2. Firing pin impression:
•firing pin marks left on cast-off cartridge casing
can also helpful in identifying a firearm
•such marks are impressions made on bottom of
cartridge by firing pin as it strikes bottom of
cartridge when firearm is shot
 Identification of Weapons and
Ammunition
3. Marks from extractors and ejectors:
•other marks left on cast-off cartridge casing
include extractor and ejector marks which are
minute scratches produced as cartridge is placed
in firing chamber (by extractor) and removed
from chamber after firing (by ejector),
•marks produced only in semiautomatic and
fully automatic weapons
Identification of Weapons and
Ammunition
 Identification of Weapons and
Ammunition
4. Marks due to expansion:
•at time of firing cartridge case expands and may
take up mark or certain irregularities which may
occur in region where barrel, the breech and the
extractor meet
 EXAMINATION
• each barrel has it own unique set of
imperfections in rifling
• no two firearm barrels, even though in
succession will have identical striations
• by examining unique striations or marking left
behind bullet as it passes through barrel and
on cartridges as it is hit by firing pin individual
cast-off rounds can be linked back to specific
weapon
 EXAMINATION
• imprints can never be duplicated by different
weapons
• fired bullets reveal both class as well as
accidental characteristics of barrel from which
bullets are fired
 EXAMINATION
• in order to determine whether or not a
particular firearm has fired questioned bullet,
a detailed comparison is made of marking on
questioned bullet with corresponding marking
of test bullet fired through suspect firearm
• any difference in class characteristics serves to
eliminate possibility that both bullets travelled
through same barrel
 EXAMINATION
• bullets seized at crime scene is greatly
deformed, or when only fragment of it are
recovered comparative chemical analysis of
question and known bullets by spectrographic
analysis may yield useful information
• when firearm is fired they produce residue –
gun shot residue (GSR)
• GSR are traces of smoke and particles of
unburned power carried sideways from the
firearm by expansion of gases as the bullet is
fired
• GSR transferred on the hands of shooter
• amount of GSR decreases as the distance
between firearm and victim increases
• detection of GSR enables the investigator in
identifying the firer and also in attempting to
recreate a crime scene
• distance between weapon and victim can be
determined by examining GSR pattern on
body of the victim
• Neutron Activation Analysis (NAA) enables
determination of level of barium or antimony
from primer mixtures of all fire ammunition
on hands of firer
• Atomic Absorption Spectrometry (AAS)
method can detect concertation of lead
around bullet holes as well as primer and GSR
on the hand of firer
• most reliable and elegant method evolved
recently is Scanning Electron Microscopy
(SEM) which identifies residue particles
eliminating all other background material
 DETERMINATION OF BULLET
TRAJECTORY
• important aspect ballistic investigation
determining where shooter was located
• investigator observe for clues at a crime scene
to enable them to calculate a bullet’s
trajectory to figure out where a shooter
discharged firearms
 DETERMINATION OF BULLET
TRAJECTORY
• trajectory is path of propelled bullet
• trajectory of a bullet is slightly curved
 HOW TO CALCULATE BULLET
TRAJECTORY
• trajectory can be calculated by finding two
reference points along flight path of
projective
• reference point can be bullet holes in an
object such wall or window or can be bullet
wound on a victim
 HOW TO CALCULATE BULLET
TRAJECTORY
• even a single victim body can have two
reference point which enable to calculate
where shooter stood- entry and exist wound
• investigator can also use laser to trace straight
line path that can help to determine position
of shooter or shooters
 HOW TO CALCULATE BULLET
TRAJECTORY
• two major forces would be acting on a bullet
once it is fired – forward force of firearm
shooter and force of gravity
• wound sustained from discharge of weapons
or ammunitions – bullet wounds
• examination of wounds on a body of victim
can determine where bullet entered and
exited
 BULLET ENTRANCE WOUND
• bullet entrance wound is smaller than exit
wound as skin is somewhat elastic and it
stretches when bullet enters body
 BULLET ENTRANCE WOUND
• entrance wound is recognized by it inverted
margins, presence of scorching, blackening,
tattooing, dirt ring, size & number of wounds
 BULLET ENTRANCE WOUND
• inversion of edges at entrance is caused by
projectile which draws skin inside
• dirt collar and contusion ring are often notice
at entrance side of wound
 BULLET ENTRANCE WOUND
• dirt ring is formed due to deposition of grease,
graphite and dirt present on bullet
• contusion ring is due to impact of projectile on
surface around wound
• shape of bullet entrance may be oval or round
 BULLET EXIT WOUND
• exit bullet wound are generally larger and are
recognized by absence of various marks found
around the entrance wound
• bleeding is much more marked at wound exist
 BULLET ENTRY AND EXIT

• entry and exit bullet would can be determined

by visualizing at clues on body
• if bullet penetrates clothing, then fibers may
be embedded in wound pointing direction of
penetration
 BULLET ENTRY AND EXIT
• if bullet is fired when muzzle is in contact with
skin, hot gases released from muzzle flash may
burn skin leaving a tell-tale mark
 BULLET ENTRY AND EXIT
• bullets usually do not travel smoothly through
victims body
• bones, organs and other tissues tend their
path causing tumbling effect
• tumbling effect bullet shows more irregular
exit would than expected
 BULLET ENTRY AND EXIT
• bullet may ricochet (rebound) off bone and do
considerable internal damage before exiting

• bullet may not exit the body at all

• if bullet has high speed it may enough energy
to pass directly through body leaving both
entrance and exit wound