Isiaka

1. BARREL
MANUFACTURE

2. FIRED BULLETS
• FIRED BULLETS have impressed and striated toolmarks that are generated by the
tool working surface of the rifled bore of the barrel.
• RIFLING is the construction of helical grooves in the bore that impart a rotary
motion, or spin to a fired bullet, thereby giving the bullet more range, stability and
accuracy

3. When the powder in the cartridges starts burning after ignition, the
extreme pressure produced by the gasses causes the rear of the
bullet to deform slightly and swell to fill the inside of the barrel.
The bullet deformation helps seal the gasses behind as it travels
down the he barrel. The bullet deformation effect is called
OBTURATION.

4. BULLET UNIQUE
CHARACTERISTICS
• Number of lands and grooves
- usually 4-6 but range from 2 to 22.
Diameter of lands and grooves
Width of lands and grooves
Depth of grooves
Degree of twist (twist is the number of inches of bore required for one complete rifling spiral)

5. Bullet Lands and GroovesRifling
• LANDS- are the raised portions between grooves inside the barrel after the
spiral grooves are cut to produce rifling.

6. Bullet Identification
• A bullet when fired under high pressure
through a hand gun having rifled barrel
expands and fills the whole cross section of
the barrel.
• Markings of lands and grooves will be quite
visible in those cases where the bullets fills
the whole cross section of the barrel when
fired.

7. Bullet Striations
• These are like guns
“fingerprints“
• Even the same make and
model of firearm will
distinctive striations.
• The pattern typically hold true
even over time.

8. Cartridge Identification
• The cartridges which
are fired from
automatic and repeating
firearms show repetitive
marks which are useful
in identification of the
type of weapon used.

9. Anatomy of Cartridge

10. CARTRIDGE CASE

11. FIREARM GENERATED MARKINGS ON
CARTRIDGE CASES

12. Firing Marks On A Cartridge Cases
1. FIRING PIN MARK
-Firing pin impression are
indentations created when the firing
pin of a firearm strikes the primer of
centre fire cartridge case or the rim
fire cartridge case.
 If the nose of a firing pin has
manufacturing imperfections or
damage, these potentially unique
characteristics can be impressed
into the metal of the primer or rim
of the cartridge case.

13. Firing Marks On A Cartridge Cases
• 2. Chamber Marks
- These are found around the
outer outside of the casing
and the result of irregularities
inside the walls of the firing
chamber.

14. Firing Marks On A Cartridge Cases
• 3.BREECH MARKS
-By far the most common impressed action
marks on cartridge cases are beech marks.
Most fired cartridge cases are identified as
having been fired by a specific firearm
through the identification of breech marks.

15. Firing Marks On A Cartridge Cases
4. EJECTOR MARKS
• -A created when cartridges cases are ejected from the
action of a firearm.. It can be either striated or impressed
but the impressed ejector marks not only can be used to
identify a cartridge case as having passed through a
firearms action they can also be an indication that the
cartridge was fired in the firearm.

17. Firing Marks On A Cartridge Cases
• 5. EXTRACTOR MARKS
-These marks are mostly found at the extracting groove of the fired cartridge
case.They are cause by its withdrawal from the chamber.

18. Firing Marks On A Cartridge Cases
• 6. SHEAR MARKS
- Another common striated action
mark are shear marks produced by
GLOCK pistols on cartridge case
primers. GLOCK pistols have
rectangular firing pin hole in their
breech face.

19. GROUP 4
 APAYAO ULYSSES
 BADING DARLENE KATE
 BALUTOC JOEFER
 BAUSO FATIMA
 CAWIS JIRAH
 DULAG CAROL
 KIBAYEN JONATHAN
 PERALTA MARK VAL
 SEREG GEMMA