Ballistics

Trajectory

The path a moving object follows through space as a function of time

Firearm Identification

determining whether a bullet or cartridge was fired by a particular weapon

Land Impression

The impression of the land on the gun barrel diagram

Groove Depression

The depression of the land on the gun barrel diagram

Rifling

the cutting of spiral grooves on the inside of the barrel of a firearm

Reason for Rifling

makes the bullet spin either left or right; more accurate

Caliber

the diamerter of the bore of a rifled firearm. The caliber is usually expressed in hundreths of an inch or millimeters. EX: 22 Cal or 9mm

Primer

any igniter that is used to initiate the firing of a gun

Gunpowder

a mixture of potassium nitrate, charcoal, and sulfur in a 75:15:10 ratio which is used in gunnery, time fuses, and fireworks

Lead Bullet

A bullet formed from a lead alloy

Flash hole

1. A hole(s) pierced or drilled through the web in the primer pocket of a metallic cartridge case. 2. The hole in the end of a battery cup primer used in shotshells. 3. The hole in a percussion nipple.

Individual Characteristics of a bullet

It is possible to determine the bullet on the left and the bullet on the right are from the same gun by matching the striations.

Cartridge Case Class Characteristics

Manufacture ( i.e.. Winchester) Shape ( i.e.. rimless, rimmed ) Caliber ( i.e.. 45 ACP, 9mm, 12gauge) Composition ( i.e.. brass, steel, plastic)

Cartridge Case Individual Characteristics

Individual cartridge case characteristics set each bullet apart completely, verses just grouping them in the same class.

Heavy Left Side

markings indicating a heavy left side (llo)

Mottled

Breech markings that look like ( : )

Firing Pin Marks

The toolmarks produced when a projecting firing pin comes into contact with a cartridge case or shotshell during the extraction, ejection cycle.

Dirt Flow Chamber Marks

Chamber marks that look like dirt flow

Shotgun Barrel

Long and made of thin steel that is very smooth on the inside

Shot

A solid missile discharged from a firearm

Powder

A mixture of potassium nitrate, charcoal, and sulfur in a 75:15:10 ratio which is used in gunnery, time fuses, and fireworks

Primer

Any igniter that is used to initiate the burning of a propellant

Crimp

make ridges into by pinching together

What happens when you pull the trigger?

The hammer should fall, causing the firing pin to strike a round in the chamber to fire the bullet out of the gun

Projectile Motion

A change in the orientation of the rotation axis of a rotating body, the curved path that an object follows when thrown, launched, or otherwise projected near the surface of Earth; the motion of objects that are moving in two dimensions under the influence of gravity

Terminal Ballistics

a sub-field of ballistics, is the study of the behavior of a projectile when it hits its target

Shock Wave

a region of high pressure travelling through a gas at a high velocity

Land

The lower part of a gun barrel diagram

Groove

The higher part of a gun barrel diagram

Cartridge Case

A cylindrical case of pasteboard, metal or the like, for holding a complete charge of powder, and often, also the bullet for a rifle, machine gun or small arm.

Class Characteristics of Bullet

Characeristics of bullets that group the bullet into a similar class, but does not point to a specific bullet.

Breech

That part of the breechblock or breech bolt which is against the head of the cartridge case or shotshell during firing.

Firing Pin

Part of the firing mechanism used in a firearm

Extracting Pin

The act of withdrawing a cartridge or cartridge case from the chamber of a firearm.

Safety

Keeps the gun from being able to fire. Keeps others safe, can be turned off easily.

Hammer

A component part of the firing mechanism which gives impulse to the firing pin or primer.

Breech Markings

Marks characteristic of the breech under the firing pin and have been used to identify a cartridge case with a specific firearm. That part of the breechblock or breech bolt which is against the head of the cartridge case or shotshell during firing.

Vertical

Breech markings that are vertical (lol)

Sandblasted

Breech markings that look sandblasted (.':':.)

Rim Dents

Breech markings that look like (><)

Mouse Ears

Breech markings that look like mouse ears (o)

Extracting Pin/Ejector Marks

Toolmarks produced upon a cartridge case on the head, generally at or near the rim, from contact with the ejector.

Curved

Not straight

Diagonal

Having an oblique or slanted direction

Spiral

To move in a coiled-path course

Light Ramp Bulging

Light ramp bulging chamber marks

Heavy Ramp Bulging

Heavy chamber marks that show ramp bulging marks

"Thin" Chamber Marks

Chamber marks that look thin.

Shotgun Shell

The shell of a shotgun!

Wad

A plastic, paper, or fiber disk used to keep ammunition components in place or separated. Most commonly associated with shotgun cartridges.

Brass

Copper and zinc

Round Nose Bullet

Bullet with a round nose

Hollow Point Bullet

A bullet that is hollow

Half Jacket

A bullet with only half the protection of a full jacket

Full Jacket

A projectile in which the bullet jacket encloses the entire bullet, with the usual exception of the base. Also called Full jacketed, Full patch, Full metal case and Ball ammunition

Comparison Microscope

A microscope that has two compound light microscopes with an optical bridge, so that two samples can be viewed in a single eyepiece. It is used to match trace evidence such as fibers and bullet casings.

Mushroom

A bullet that has expanded upon impact to a mushroom-like shape, or designed to so expand.

Fragmented

broken into small fragments

Gunshot Residue

The total residues resulting from the discharge of a firearm. It includes both gunpowder and primer residues, plus metallic residues from projectiles, fouling, etc.

Major Elements in GSR

Lead, Antimony & Barium

Griess Test

Detects nitrites; shows whether you've fired a gun recently

Web Area

1. The solid portion of a brass centerfire cartridge case between the inside of the case at the head end, and the bottom of the primer pocket. 2. The smallest dimension of a smokeless powder granule.

Contact Entrace Wound

Causes more damage than a normal entrance wound

Abrasion Ring

Marks produced when a tool is placed against another object, and with pressure applied, the tool is moved across the object producing a striated mark. Friction marks, abrasion marks, and scratch marks are terms commonly used when referring to striated marks. These marks can be either class and/or individual characteristics.

Entrance Wound

The wound made by a bullet when it enters a human body or other substance.

Exit Wound

The wound made by a bullet exiting the human body or othersuch object which it has penetrated

Powder Tattooing

A geographic appearance on the skin caused by a gun fired at close range, in which the still-burning gunpowder embeds in the skin and cannot be wiped away; the PT helps determine whether clothing was worn over an entrance wound.

Path of the Bullet

The path that the bullet travels from the gun barrel to its stopping place (ex. a kidney or a grassy area)

How do you find the location of the shooter?

Use the trajectory of the bullets, and use this formula! y = yo - vo(sin(θ))t - (.5)(9.8)t^2

Internal Balllistics

The study of velocity and trajectory of a projectile from the firing to the gun til it exits the gun

External Ballistics

The study of velocity and trajectory of projectile from weapon to target

Yaw

Deviation from linear flight. Ex. plane spinning from nose to tail circularly.

Precession

The motion of a spinning body (as a top) in which it wobbles so that the axis of rotation sweeps out a cone

Mutation

a change in the sequence of DNA

Permanent Cavity

i. Temporary cavity is the conical shape caused by the bullet. ii. Bullet may hit bone and change direction

Termporary Cavity

A cavity that is created by a bullet that is only temporary and can heal (ex. human tissue)

Wound Profiles

Profiles of wounds made by bullets.