Forensic ballistics - is the science of analyzing firearms usage in crimes. It involves analysis of bullets and bullets impact to determine information of use to a court or other part of legal system. Separately from the ballistics information, firearm and tool mark examinations also involves analyzing firearm, ammunition and tool mark evidence in order to established whether a certain firearm or tool was used in the commission of crime.
Ballistics -(ballein "to throw") - is the science of mechanics that deals with the flight, behavior and effects of projectiles especially bullet, gravity bombs, rockets or the like.
Ballistic missile - is a missile, only guided during the relative brief initial powered phase of flight whose course is subsequently governed by the laws of classical mechanics.
Flight - is the process by which an object moves through an atmosphere by generating aerodynamic lift, propulsive thrust, aerostatically using buoyancy or by ballistic movement without any direct solid mechanical support from the ground.
Firearms identification - the identification of fired bullets, cartridge cases or other ammunition components as having been fired from a specific firearm.
Rifling - is the process of making helical grooves in the barrel of a gun or firearm which imparts a spin to a projectile around its long axis. This spin stabilize the projectile, improving its stability and accuracy.
Projectile - is any object projected into space by the exertion of a force.
Trajectory - is the path that a moving object follows through space as a function of time.
Firearm - is a weapon that launches one or many projectiles at high velocity through confined burning of a propellant.
Ballistic fingerprinting - involves analyzing firearm, ammunition and tool mark evidence in order to establish whether a certain firearm or tool was used in the commission of a crime.
Gun ballistic - is the work of projectile from the time of shooting to the time of impact with the target.
Four categories of gun ballistics
Colonel Calvin Hooker Goddard - father of forensic ballistic.
Some Factors to be Considered in designing a Firearm
1. reliability of firing
2. accuracy of projectile
3. force of projectile
4. speed of firing
Characteristics of a Muzzle Loader Firearm
1. powder and bullet loaded from top of the barrel
2. smooth bore with a round lead ball.
3. limited range and accuracy
Accuracy is Increased
1. by longer bore or length of metal tube
2. putting spiral grooves in the bore (riffling)
Breech loading firearm - is a firearm in which the cartridge or shell is inserted or loaded into a chamber integral to the rear portion of a barrel.
Sir Hiram Maxim - an American inventor of the machine gun or the maxim gun.
Richard Gatling - inventor of the Gatling gun, a machine gun with a six barrel capable of firing 200 rounds per minute at the earliest stages of development.
Gatling Gun - a hand driven, crank operated multi barrel machine gun.
note: velocities of bullets are increased with the use of a jacket of a metal such as copper or copper alloys that covers a lead core and allow the bullet to glide down the barrel more easily than exposed lead. Such bullets are less likely to fragment on impact and are more likely to traverse through a target while imparting less energy.
Fouling - deposits of unburned powder residue in the bore of a gun.
What is the indispensable tool of the firearm examiner? comparison microscope.
1. Action - the part of the firearm that loads, fires,
and ejects a cartridge.Includes lever action,pump
action, bolt action,and semi-automatic.The first
three are found in weapons that fire a single shot.
Firearms that can shoot multiple rounds "repeaters"
include all these types of actions but only the semi-
automatic does not require manual operation
between rounds.A truly automatic action is found
on a machine gun.
2. Barrel - the metal tube through which the bullet
3. Black Powder - the old form of gun powder
invented over a thousand years ago and consisting
of nitrate,charcoal,and sulfur.
4. Bore - the inside of the barrel.
5. Breech - the end of the barrel attach to the action
6. Bullets - is a projectile propelled by firearm,sling,
airgun.They are shaped or composed differently for
a variety of purposes.
is held or shouldered.
8. Caliber - the diameter of the bore measured from
land to land , usually expressed in hundredths of an
inch (.22 cal) or in millimeters (9mm).
9. Cartridge - also called a round - packages the
bullet, propellant and primer into a single unit within
a containing metallic case that is precisely made to
fit within the firing chamber of a firearm.
Parts of a cartridge
10. Centerfire - the cartridge contains the primer in
the center of the base where it can be struck by
firing pin of the action.
11. Chamber - the portion of the action that holds
the cartridge ready for firing.
12. Choke - a constriction of a shotgun bore at the
muzzle that determines the pattern of the fired
13. Double Action - Pulling the trigger both cocks
the hammer and fires the gun.
14. Double Barrel - two barrels side by side or one
on top of the other usually on a shotgun.
15. Gauge - refers to the diameter of the barrel on a
shotgun in terms of the number of lead balls the
size of the bore it would take to weigh one pound
(10 gauge,12 gauge etc) "410" gauge really refer
to caliber,but it is worded as such to refer to a
16. Hammer - a metal rod or plate that typically
drives a firing pin to strike the cartridge primer to
detonate the powder.
17. Ignition - the way in which powder is ignited.Old
muzzle loading weapons used flintlock or
percussion caps.Modern guns use primers that are
rimfire or centerfire.
18. Lands and Grooves - lands are the metal inside
the barrel left after the spiral grooves are cut to
produce the rifling.
19. Magazine - this is a device for storing cartridges
in a repeating firearm for loading into the chamber.
20. Magnum - for rifles and handguns, an improved
version of a standard cartridge which uses the
same caliber and bullets,but has more powder,
giving the fired bullet more energy.For shotgun
loads,magnum shells have more powder and may
have increased length with more shot pellets.
21. Muzzle - the end of the barrel out of which the
22. Pistol - synonym for a handgun that does not
have a revolving cylinder.
23. Powder - modern gun cartridges use smokeless
powder that is relatively stable,of uniform quality,
and leaves little residue when ignited.For centuries
black powder was used and was quite volatile
(ignited at low temperature or shock),was
composed of irregularly sized grains,and left a
heavy residue after ignition,requiring frequent
cleaning of bore.
24. Primer - a volatile substance that ignites when
struck to detonate the powder in a cartridge.
holes to contain the cartridges.The cylinder
revolves to bring the cartridge into position to be
fired.This is a single action when the hammer must
be cocked before the trigger can fire the weapon.
It is double action when pulling the trigger both
cock and fires the gun.
26. Riffling - the spiral grooves cut inside a gun
barrel that give the bullet a spinning motion.The
metal between the grooves is called a land.
27. Rimfire - the cartridge has the primer distributed
around the periphery of the base.
28. Safety - a mechanism of an action to prevent
firing of the gun.
29. Shotgun - a gun with a smooth bore that shoots
cartridges that contain "shot" or small metal pellets
of lead or steel as the projectiles.
30. Smoothbore weapons - have no riflings,
typically shotguns.Most handguns and rifles have
31. Sights - the device on top of the barrel that allow
the gun to be aimed.
32. Silencer - a device that fits over the muzzle of
the barrel to muffle the sound of a gunshot.Most
work by baffling the escape of gases.
33. Single Action - the hammer must be manually
cocked before the trigger can be pulled to fire the
34. Smokeless Powder - refers to modern gun
powder which is not really powder but flakes or
nitrocellulose and other substances.Not really
smokeless but much less so than black powder.
35. Stock - a wood,metal,or plastic frame that holds
the barrel and action and allows the gun to be held
Composition of Gunpowder
3. Saltpeter (potassium nitrate)
- gun powder first appeared in china but used
primarily in firecrackers.
Different Firing Mechanisms of Firearm
1. Matchlock - employed a burning wick on a spring
that was "locked" back and released into a pan of
powder upon pulling a trigger. The powder in the
pan then ignited, sending flame through a small
hole into the barrel chamber of the weapon,
igniting a larger powder charge in the chamber and
sending the projectile (bullet) forward.
2 Wheellock - in the early 16th century, improvement
included the wheellock mechanism in which a
spinning wheel against a metal plate showered
sparks into the pan holding the priming powder.
3. Flintlock - developed in the early 17th century,
flint is released by the trigger mechanism that
strikes a steel plate to shower sparks into the pan
filled with powder.
4. Percussion - evolved in the 19th century,
consisted of a hammer that was locked and when
released, struck a cap containing a volatile
"primer" that ignites on impact, sending a flame
through a small tube into the barrel chamber.
- next, inventors combined the individual components
including the bullet, powder charge and primer all in
a single cartridge which could be introduced directly
into the chamber.
Definition of Terms: Next Page
Related Readings: Forensic Ballistics
1. Forensic Ballistics Definition of Terms
2. Questioned Document Definition of Terms