On bullets, the class characteristics are the rifling specifications of the barrel from which the bullet was fired . These include caliber, number of lands and grooves, direction of twist of the lands and grooves, and widths of the lands and grooves.
What are gun class characteristics?
There are several general characteristics associated with the firearm that can help lead the investigation. These include the calibre of the barrel, the number and dimension of the grooved impressions inside the barrel , the direction of the twist of these rifling grooves, and different marks on the cartridge case.
What are class and individual characteristics in firearm identification?
Class characteristics are not unique to a particular object but place the particular bit of evidence into a group of objects. Individual characteristics narrow down the evidence to a single, individual source . The type of handgun with which a victim is shot is a class characteristic.
What are individual characteristics analyzed on bullets?
Some of the class characteristics found on a fired bullet are (1) the caliber of the bullet (diameter) , (2) the number of lands and grooves, (3) the twist of the rifling (left or right), and (4) the widths of the land and groove impressions.
What are examples of class characteristics?
- A collection of miscellaneous hammers.
- the chemical structure of heroin molecules.
- the tread patterns on a brand of new athletic shoes.
- the species source of a blood sample.
- the ABO typing of a blood sample (ie: AB negative)
What is a class characteristic?
Class Characteristics are properties of physical evidence that can be associated only with a group and never with a single source . ... Examples of class evidence include blood type, fibers, and paint.
What are class characteristics of handwriting?
Class Characteristics are those writing features common to a group i.e. the common pattern of handwriting, letters , their shape which are limited to a group, age or language.
Are gun rifling unique?
Manufacturers use various cutting, swaging and electrolytic processes to introduce rifling into a barrel, and these processes, as well as others used in the finishing of a firearm, make each barrel unique .
What is the purpose of rifling in a gun?
In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun’s barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the projectile longitudinally by conservation of angular momentum , improving its ...
What is a bullet called?
Cartridge : A unit of ammunition, made up of a cartridge case, primer, powder, and bullet. Also called a “round”, or “load”. Sometimes incorrectly called a “bullet”.
What causes a specific firearm to be unique?
Individual characteristics are marks unique to that particular firearm barrel. In a barrel, the individual characteristics are produced by the random imperfections and irregularities of the tool or tools used to produce the lands and grooves, and by use, corrosion, or damage.
What are the bullets principles of identification?
These include the caliber (bore diameter) of the barrel, the number and dimension of the grooved impressions inside a gun barrel , and the direction of the twist of these rifling grooves (clockwise or counterclockwise). To help stabilize the flightpath of a bullet, manufacturers cut spiral grooves into the gun barrel.
What are the three categories of ballistics?
The science of projectiles and firearms is defined as ‘ballistics’ and it can be divided into three distinct categories: internal, external and terminal .
What are the two types of bullet impressions?
The two most common impressed action marks are firing pin impressions and breech marks .
What are the markings on a bullet called?
To evaluate old bullets, ballistics experts rely on the same basic techniques used at police labs. Most clues are found in two types of tiny markings, called class and individual characteristics. By looking for the bullet caliber and “rifling” marks , experts can identify the type of gun used.
What are the three characteristic composition of a gun?
Main components of a firearm
The more common parts include the barrel, magazine, hand guard, pistol grip, trigger and the trigger guard . All firearms have a receiver, which is comprised of springs, levers and pistons.
