Transcript BALLISTICS - CSI: Coronado

BALLISTICS
Firearms and Cartridges
Terms
Ballistics: the study of bullets and
firearms
 Firearms: a weapon capable of firing a
projectile using a confined explosive

History
Gunpowder was invented by the Chinese
more than 1,000 years ago
 It is a combination of potassium nitrate,
charcoal, and sulfur that expands to 6x its
size when ignited
 The first guns were developed in Europe
during the 14th century

Early Weapons

Matchlock:
◦ These weapons had wicks to carry a flame to
the gunpowder
◦ These weapons were muzzle-loaders
◦ The powder and projectile were put down
the firearm’s barrel (muzzle) and packed into
place
Early Weapons (cont.)

Flintlock:
◦ These weapons used sparks from a chip of
flint to ignite the gunpowder
◦ These weapons were muzzle-loaders
Percussion Firing
Replaced the flintlock method of firing
 Started with the introduction of a
cartridge, which is a case that holds a
bullet, a small amount of primer powder,
and the gunpowder
 A hammer hits the primer powder, which
explodes to ignite the gunpowder
 Cartridges are loaded opposite the barrel
(breech) so these weapons are called
breech-loaders

Semiautomatic vs. Fully automatic
A semiautomatic fires only one bullet per
pull of the trigger
 A fully automatic fires repeatedly as long
as the trigger is pressed
 In both weapons, the empty cartridge
ejects and the next cartridge advances
automatically

Hand Guns

Designed to be fired with one hand and
are called pistols; classified into:
◦ Revolvers--Hold 6 cartridges in a cylinder
that turns as the weapon is fired
◦ Semiautomatic Pistols
Single vs Double Action Revolvers
Single Action revolvers require cocking
the hammer and pulling the trigger to
release the hammer
 In Double Action revolvers the trigger
cocks the hammer and causes it release

Semiautomatic Pistol

Hold up to 10 cartridges in a magazine
(a.k.a. clip), which is locked into the grip
of the firearm
Long Guns

Require the use of two hands for
accurate firing; include:
◦ Rifles—fire bullets
◦ Shotguns—fire either small round pellets
(shot) or a single projectile (slug)
Rifles
Bolt Action: manually loaded and
unloaded by rotating a bolt into position
 Lever Action: manually loaded and
unloaded by an external lever

Shotgun

Pump Action: features a movable forearm
which is manually actuated in motion
parallel to the barrel by the shooter
Rifling
To increase the accuracy of a shot, a
projectile should have a twist
 The barrel of a weapon has raised areas
(lands) and indentations (grooves) that
cause the bullet to spiral as it exits

Rifling (cont.)
Rifling refers to the pattern left on a
bullet by the lands and grooves
 Because it is impossible to produce two
identically rifled gun barrels, a bullet can
be matched to the specific gun from
which it was fired

Cartridge

A typical cartridge
contains:
◦
◦
◦
◦
◦
Bullet
Primer powder
Gunpowder
Casing material
Anvil and flash hole: which delivers the
explosive charge from the primer to the
gunpowder
◦ Headstamp: identifies the caliber and
manufacturer
Caliber
Bullets and their cartridges are named by
caliber and length
 The caliber is a measure of the diameter
of the cartridge measured in hundredths
of an inch
 Common calibers include .22, .25, .357,
.44 and .45

Caliber (cont.)
Sometimes calibers can be measured in
mm
 Caliber also refers to the diameter of the
inside of a firearm’s barrel
 The caliber of ammunition should match
the firearm that shoots it

How a Firearm Works
The firing
pin hits the
base of the
cartridge
and ignites
the primer
powder
The tiny explosion causes the anvil to
deliver a spark to the main gunpowder
supply
Pull the trigger
How a Firearm Works (cont.)
The gunpowder ignites and the
explosion pushes the bullet from the
casing and into the barrel where it
follows the lands and grooves pattern
and begins its spiral before it exits