When a firearm is discharged, a cartridge case comes in clase contact with the firing pin, the breech face, the extractor, the ejector and the chamber. The fired projectiles come in close
contact with the lead and the barrel.
These parts undergo processes like cutting, hammering, reaming, grinding, filing and polishing. Various tools are used for the purpose. The surface profiles of the tools used continue to change due to wear and tear as the tools work on steel.
Forensic Ballistics is a branch of forensic science which deals with shooting incidents for the purpose of justice. Matching and identification of cartridge cases and bullets plays a key role in identifying the firearm.
This document discusses principles and practices of firearm identification in forensic science. It defines key ballistics terms and describes how class and individual characteristics can be used to identify firearms. Specific characteristics examined include rifling marks, firing pin impressions, breech face marks, and striations. Methods of comparing bullets and cartridge cases using comparison microscopes, stereomicroscopes, test firing, and automated databases like NIBIN and IBIS are summarized. The document provides an overview of the field of forensic ballistics and firearm identification.
Explanation of ballistics, various fields of ballistics, Forensic Ballistics,Firearms and its components, Ammunition and its components, firing mechanism of firearm, Identification & individualization.
This document summarizes different types of firearms and toolmarks evidence that may be analyzed in criminal investigations. It discusses various firearms like handguns, revolvers, semi-automatics, rifles and shotguns. It also covers topics like barrel markings, ammunition, firing mechanisms, gunshot wounds, gunpowder residue, toolmarks, impressions and bite mark analysis. Firearms examiners analyze these different types of forensic evidence and compare evidence from crime scenes to suspect weapons using techniques like microscopy.
Firearms identification experts can identify key details about firearms from ballistic evidence:
- Rifling marks on bullets can identify the specific gun used due to variations between firearms.
- Firing pin and breechblock markings on cartridge casings are also unique to each gun.
- The type of bullet, firearm, and presence of gunshot residue can provide important clues during investigations.
Examination of Firearm through Cartridge Case and bullet.pptxPallaviKumari112
The document summarizes the capabilities and examination process of forensic firearm experts. It discusses how experts can identify bullets and cartridge cases even without a suspect firearm by analyzing characteristics like weight, lands and grooves. The examination process involves comparing test-fired bullets and cartridge cases to evidence items under a comparison microscope, looking at matching striations, marks and impressions that can identify the firearm used. It also discusses an Automatic Bullet Identification System (ABIS) that uses computers and algorithms to automate the process of matching ballistic evidence to databases.
1. Firearms analysis examines guns, bullets, and cartridge casings to determine if a specific gun was used in a crime. Microscopic marks left on bullets and casings when fired provide unique "fingerprints" that can identify the weapon used.
2. Gun barrels leave distinct striation marks on bullets that pass through them. Comparing test-fired bullets to evidence bullets under a microscope can match bullets to the firearm from which they were fired.
3. Other toolmarks left on cartridge casings, such as firing pin impressions and ejector marks, also provide identifying patterns that link spent casings to a particular firearm. The combination of these factors allows forensic experts to determine if a gun was used in
This document provides information on firearms and ballistics, including the components of ammunition, how guns work, gunshot residue, bullet trajectory, bullet penetration, shotgun pellet patterns, rifling determination from ricochet marks, cartridge case ejection patterns, and the effects of projectiles on common materials like glass. Key topics covered include the primer, cartridge case, propellant, and projectile in ammunition, as well as how examination of gunshot residue particles can provide information about whether an individual fired or handled a weapon.
Forensic Ballistics is a branch of forensic science which deals with shooting incidents for the purpose of justice. Matching and identification of cartridge cases and bullets plays a key role in identifying the firearm.
This document discusses principles and practices of firearm identification in forensic science. It defines key ballistics terms and describes how class and individual characteristics can be used to identify firearms. Specific characteristics examined include rifling marks, firing pin impressions, breech face marks, and striations. Methods of comparing bullets and cartridge cases using comparison microscopes, stereomicroscopes, test firing, and automated databases like NIBIN and IBIS are summarized. The document provides an overview of the field of forensic ballistics and firearm identification.
Explanation of ballistics, various fields of ballistics, Forensic Ballistics,Firearms and its components, Ammunition and its components, firing mechanism of firearm, Identification & individualization.
This document summarizes different types of firearms and toolmarks evidence that may be analyzed in criminal investigations. It discusses various firearms like handguns, revolvers, semi-automatics, rifles and shotguns. It also covers topics like barrel markings, ammunition, firing mechanisms, gunshot wounds, gunpowder residue, toolmarks, impressions and bite mark analysis. Firearms examiners analyze these different types of forensic evidence and compare evidence from crime scenes to suspect weapons using techniques like microscopy.
Firearms identification experts can identify key details about firearms from ballistic evidence:
- Rifling marks on bullets can identify the specific gun used due to variations between firearms.
- Firing pin and breechblock markings on cartridge casings are also unique to each gun.
- The type of bullet, firearm, and presence of gunshot residue can provide important clues during investigations.
Examination of Firearm through Cartridge Case and bullet.pptxPallaviKumari112
The document summarizes the capabilities and examination process of forensic firearm experts. It discusses how experts can identify bullets and cartridge cases even without a suspect firearm by analyzing characteristics like weight, lands and grooves. The examination process involves comparing test-fired bullets and cartridge cases to evidence items under a comparison microscope, looking at matching striations, marks and impressions that can identify the firearm used. It also discusses an Automatic Bullet Identification System (ABIS) that uses computers and algorithms to automate the process of matching ballistic evidence to databases.
1. Firearms analysis examines guns, bullets, and cartridge casings to determine if a specific gun was used in a crime. Microscopic marks left on bullets and casings when fired provide unique "fingerprints" that can identify the weapon used.
2. Gun barrels leave distinct striation marks on bullets that pass through them. Comparing test-fired bullets to evidence bullets under a microscope can match bullets to the firearm from which they were fired.
3. Other toolmarks left on cartridge casings, such as firing pin impressions and ejector marks, also provide identifying patterns that link spent casings to a particular firearm. The combination of these factors allows forensic experts to determine if a gun was used in
This document provides information on firearms and ballistics, including the components of ammunition, how guns work, gunshot residue, bullet trajectory, bullet penetration, shotgun pellet patterns, rifling determination from ricochet marks, cartridge case ejection patterns, and the effects of projectiles on common materials like glass. Key topics covered include the primer, cartridge case, propellant, and projectile in ammunition, as well as how examination of gunshot residue particles can provide information about whether an individual fired or handled a weapon.
Firing marks left on bullets and cartridge cases can be used to identify the firearm used. There are several types of marks including:
1. Rifling marks on the bullet from the grooves in the barrel. These marks are unique to each gun.
2. Firing pin marks on the primer from the firing pin striking it. Imperfections in the firing pin can be transferred.
3. Breech face marks on the cartridge from the cartridge striking the breech face on firing. Imperfections are imprinted.
4. Extractor and ejector marks on the cartridge case from the mechanisms removing the spent case from the firearm.
Firearm injuries and its MLI ppt -89.pptxDrSathishMS1
This document provides an overview of firearms and injuries caused by them. It defines a firearm as any device that propels a projectile via combustion, and discusses their typical components. Firearms are classified based on their barrel characteristics, such as whether the barrel is smooth or rifled. Rifled firearms impart spin to bullets, increasing accuracy and range. The document examines the wound patterns and injuries caused by different types of firearms. It provides guidance for forensic doctors on examining firearm-related autopsy cases.
The document describes the design and creation of a homemade high-powered Nerf gun. The author sought to create a gun with greater range and accuracy than commercial Nerf guns through examining dart and gun physics, evaluating past designs, and designing unique trigger and barrel indexing systems. Construction problems required creative solutions. The completed gun meets the design goals of 70+ foot range and improved accuracy over Nerf elite blasters, though the dart storage system requires repair. The project provided a valuable learning experience in engineering design challenges.
Tool marks evidence plays an important role in forensic science. Tool marks are impressions or marks left on surfaces by tools and can be used to identify the specific tool that made the mark. There are different types of tool marks such as impressions, abrasions, cuts, and drill holes. Tool marks contain both class characteristics common to groups of tools and unique individual characteristics. Tool marks are collected using methods like photography, casting, and test marks. Examiners compare both class and individual characteristics of tool marks using various techniques like microscopy and superimposition to determine if two marks have a common origin.
A comparison microscope allows two specimens to be viewed simultaneously through two connected microscopes. This avoids having to switch between specimens under a single microscope. Comparison microscopes are useful in fields like forensics, paleontology, and archaeology for comparing ballistics evidence, tool marks, and other small objects. They were pioneered in firearms examination in the 1920s and allow examiners to compare unique striations on bullets and cartridge casings to link them to specific guns. The microscope uses an optical bridge between two microscopes to combine their images into a single eyepiece for side-by-side comparison.
This document discusses the mechanisms of armour penetration by kinetic projectiles. There are three main mechanisms of penetration: dishing, punching, and ductile hole enlargement. Dishing occurs when the projectile diameter is much larger than the armour thickness. Punching requires a blunt impact and very high shear stresses. Ductile hole enlargement is the dominant mechanism when the projectile diameter is close to the armour thickness. The ability of a projectile to penetrate armour depends on its kinetic energy, which is determined by its mass and velocity. The shape and material properties of both the projectile and armour also influence penetration. Mathematical models can predict penetration based on these factors.
This document provides information about firearms and toolmarks analysis in crime scene investigations. It describes key parts of guns like the barrel, cartridge case, slide, and firing pin. It explains how guns work and the components of cartridges, including the primer, smokeless gunpowder, and projectile. It also details characteristics of bullets like rifling impressions, striations, caliber and rifling number that can be analyzed to determine if a specific gun was involved. Firearms examiners analyze both class characteristics common to a brand and individual characteristics unique to a single firearm.
This document provides information about firearms and toolmarks analysis in crime scene investigations. It describes key parts of guns like the barrel, cartridge case, slide, and firing pin. It explains how guns work and the components of cartridges, including the primer, smokeless gunpowder, and projectile. It also details characteristics of bullets like rifling impressions, striations, caliber and rifling number that examiners analyze to determine if a specific gun was involved in a shooting. Class characteristics refer to marks that are common to a brand or type of firearm, while individual characteristics are unique to a single firearm.
This document defines and describes the science of ballistics and its branches. It discusses (1) the types of projectile motion, (2) the branches of ballistics including interior, exterior and terminal ballistics, (3) the components and mechanics of firearms, and (4) the classification of firearms according to their construction and operation. Forensic ballistics is defined as the application of ballistics to criminal investigations through examination of evidence such as bullets, shells, and firearms.
This document defines and describes key concepts in ballistics and forensic ballistics. It discusses:
- The definition and branches of ballistics, including interior, exterior, and terminal ballistics.
- Components of firearms like barrels, ammunition, bullets, and their classifications.
- The definition and scope of forensic ballistics, which examines ballistics evidence like bullets, shells, and firearms used in crimes.
This document summarizes a group project analyzing rocket nozzle designs through computational fluid dynamics (CFD) modeling and experimental testing. The group modeled and tested four nozzle types - orifice, converging, diverging, and converging-diverging. Their CFD modeling in FLUENT found the converging-diverging nozzle produced the highest thrust of 7.5 oz. Their experimental testing of homemade rockets found similar results, with the converging-diverging nozzle generating 0.9 oz of thrust, the highest amount. Both their computational and experimental results showed the converging-diverging nozzle design to be the most efficient and capable of the highest thrust.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
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Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
Contenu connexe
Similaire à Different types of marks produce during firing process
Firing marks left on bullets and cartridge cases can be used to identify the firearm used. There are several types of marks including:
1. Rifling marks on the bullet from the grooves in the barrel. These marks are unique to each gun.
2. Firing pin marks on the primer from the firing pin striking it. Imperfections in the firing pin can be transferred.
3. Breech face marks on the cartridge from the cartridge striking the breech face on firing. Imperfections are imprinted.
4. Extractor and ejector marks on the cartridge case from the mechanisms removing the spent case from the firearm.
Firearm injuries and its MLI ppt -89.pptxDrSathishMS1
This document provides an overview of firearms and injuries caused by them. It defines a firearm as any device that propels a projectile via combustion, and discusses their typical components. Firearms are classified based on their barrel characteristics, such as whether the barrel is smooth or rifled. Rifled firearms impart spin to bullets, increasing accuracy and range. The document examines the wound patterns and injuries caused by different types of firearms. It provides guidance for forensic doctors on examining firearm-related autopsy cases.
The document describes the design and creation of a homemade high-powered Nerf gun. The author sought to create a gun with greater range and accuracy than commercial Nerf guns through examining dart and gun physics, evaluating past designs, and designing unique trigger and barrel indexing systems. Construction problems required creative solutions. The completed gun meets the design goals of 70+ foot range and improved accuracy over Nerf elite blasters, though the dart storage system requires repair. The project provided a valuable learning experience in engineering design challenges.
Tool marks evidence plays an important role in forensic science. Tool marks are impressions or marks left on surfaces by tools and can be used to identify the specific tool that made the mark. There are different types of tool marks such as impressions, abrasions, cuts, and drill holes. Tool marks contain both class characteristics common to groups of tools and unique individual characteristics. Tool marks are collected using methods like photography, casting, and test marks. Examiners compare both class and individual characteristics of tool marks using various techniques like microscopy and superimposition to determine if two marks have a common origin.
A comparison microscope allows two specimens to be viewed simultaneously through two connected microscopes. This avoids having to switch between specimens under a single microscope. Comparison microscopes are useful in fields like forensics, paleontology, and archaeology for comparing ballistics evidence, tool marks, and other small objects. They were pioneered in firearms examination in the 1920s and allow examiners to compare unique striations on bullets and cartridge casings to link them to specific guns. The microscope uses an optical bridge between two microscopes to combine their images into a single eyepiece for side-by-side comparison.
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This document provides information about firearms and toolmarks analysis in crime scene investigations. It describes key parts of guns like the barrel, cartridge case, slide, and firing pin. It explains how guns work and the components of cartridges, including the primer, smokeless gunpowder, and projectile. It also details characteristics of bullets like rifling impressions, striations, caliber and rifling number that can be analyzed to determine if a specific gun was involved. Firearms examiners analyze both class characteristics common to a brand and individual characteristics unique to a single firearm.
This document provides information about firearms and toolmarks analysis in crime scene investigations. It describes key parts of guns like the barrel, cartridge case, slide, and firing pin. It explains how guns work and the components of cartridges, including the primer, smokeless gunpowder, and projectile. It also details characteristics of bullets like rifling impressions, striations, caliber and rifling number that examiners analyze to determine if a specific gun was involved in a shooting. Class characteristics refer to marks that are common to a brand or type of firearm, while individual characteristics are unique to a single firearm.
This document defines and describes the science of ballistics and its branches. It discusses (1) the types of projectile motion, (2) the branches of ballistics including interior, exterior and terminal ballistics, (3) the components and mechanics of firearms, and (4) the classification of firearms according to their construction and operation. Forensic ballistics is defined as the application of ballistics to criminal investigations through examination of evidence such as bullets, shells, and firearms.
This document defines and describes key concepts in ballistics and forensic ballistics. It discusses:
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- The definition and scope of forensic ballistics, which examines ballistics evidence like bullets, shells, and firearms used in crimes.
This document summarizes a group project analyzing rocket nozzle designs through computational fluid dynamics (CFD) modeling and experimental testing. The group modeled and tested four nozzle types - orifice, converging, diverging, and converging-diverging. Their CFD modeling in FLUENT found the converging-diverging nozzle produced the highest thrust of 7.5 oz. Their experimental testing of homemade rockets found similar results, with the converging-diverging nozzle generating 0.9 oz of thrust, the highest amount. Both their computational and experimental results showed the converging-diverging nozzle design to be the most efficient and capable of the highest thrust.
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Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
Temple of Asclepius in Thrace. Excavation resultsKrassimira Luka
The temple and the sanctuary around were dedicated to Asklepios Zmidrenus. This name has been known since 1875 when an inscription dedicated to him was discovered in Rome. The inscription is dated in 227 AD and was left by soldiers originating from the city of Philippopolis (modern Plovdiv).
2. Principle
When a firearm is discharged, a cartridge case comes in close
contact with the firing pin, the breech face, the extractor, the
ejector and the chamber. The fired projectiles come in close contact
with the lead and the barrel.
These parts undergo processes like cutting, hammering, reaming,
grinding, filing and polishing. Various tools are used for the
purpose. The surface profiles of the tools used continue to change
due to wear and tear as the tools work on steel.
The finished surface profiles of the relevant parts of the firearms
after undergoing such operations are, therefore, different pattern,
even when the two surfaces are made with the same set of tools,
one after the other.
Consequently, all the firearms, even the two barrels of the same
firearm, are individualistic, unique.
The peculiarities of the various parts of a firearm are enhanced with
the use of the firearm due to wear and tear and accidental damage.
When a cartridge is fired, the cartridge case and the bullet come in
close contact with the relevant parts of the firearm. A negative
profile of the surface (of the firearm) is imprinted on surfaces of the
fired cartridge case/projectile when the two surfaces come in close
contact with force. The negative profile is called the thumbprint of
the firearm. It permits its linkage with the used firearm only.
3. Class and
Individual
Characteristics
The position, size and the general shape of the firing pin, the breech face, the
extractor, the ejector and of the chamber marks on a cartridge are the class
characteristics of the firearm.
No two firearms, even of the same make and model, produced one after the
other, will leave identical marks on the fired ammunition.
In a fired bullet, the calibre and the number, width, depth, direction, angle and
twist of the grooves and lands form the class characteristics.
The firearms of the same make and model imprint common class characteristics
on fired ammunition. The firearm of different makes or of different models of
same make, usually, imprint different class characteristics.
The finer details in the lands and grooves and individual characteristics of the
firearm. The individual features are always different. No two firearms have the
same individual characteristics.
6. Firing Pin
The firing pin strikes the cartridge on the percussion cap
and imprints its mark.
The impact explodes the cap composition.
The flame and the heat produced, rapidly convert the
propellant charge into gases.
The high pressure developed presses the case against
the firing pin.
The clarity of the firing pin marks is thus, enhanced.
7. Breech Face
The surface of the action block surrounding the firing pin is breech
face. On firing, the gases push the cartridge case violently against
the breech face, which imprints its negative profile on the cartridge
base.
The breech face profile is highly characteristic. It, alone, is sufficient
for the identification of the firearm used if the profile on the base of
the cartridge is clear.
The breech face marks are often absent on the cartridges which
develop low pressures. When the ammunition develops high
pressure, breach face marks are printed.
8. Chamber
The standard (made to specifications) factory made firearms seldom
leave chamber marks on the fired ammunition. When the chamber has
some defect or some deposit it imprints its negative profile on the
tubular portion of the cartridge case.
An over-sized cartridge (case) may also register chamber mark Improvised
firearms often create chamber marks on the cartridges fired from them,
because there is no adequate space for the normal expansion of the cartridge
case, on firing. The chamber marks permit the linkage of the firearm with the
fired cartridge.
In India, conventional structure of chambers continues. Western countries and
China has modified the internal structure of chambers, in some firearms:
1. Chambers are over-sized.
2. The chamber is fluted. It may be simple flute or may be helical.
3. The chambers are perforated.
4. Annular rings are created.
The changes in the chambers are intended to accelerate/retard the cartridge
case. Cartridges fired from such modified chambers, carry characteristic
marks: They are useful to link the cartridge case with the firearm.
The clarity of the marks varies and depends upon the nature of the charges,
the pressure developed in the firing process, the nature of the tubular surface
of the cartridge and the size of the chamber.
9. Extractor
Extractor marks, like chamber marks, are rarely significant. They may
permit the identification of the firearm, in some cases, whenever the prints
are clear. Extractor marks help in fixing the orientation of the cartridge in
the chamber. The orientation is often helpful in locating the part of the
breechblock (or other parts) which may have imprinted the marks on the
cartridge case.
Ejector
In automatic and semi-automatic firearms, the ejector stamps its marks on
the cartridge case when it strikes against it, in its backward motion. The
ejector is so positioned that the fired shell, after striking the device, is
pushed out of the firearm. The ejector marks may link the fired shells with
the used firearm. The clarity of the marks, however, varies tremendously
from one firearm to another and even from one shot to another in the
same firearm. The marks are, therefore, more useful as class characteristics
to fix or eliminate the brand of the firearms.
10. Ejector
In automatic and semi-automatic firearms, the ejector stamps its marks on
the cartridge case when it strikes against it, in its backward motion. The
ejector is so positioned that the fired shell, after striking the device, is
pushed out of the firearm. The ejector marks may link the fired shells with
the used firearm. The clarity of the marks, however, varies tremendously
from one firearm to another and even from one shot to another in the
same firearm. The marks are, therefore, more useful as class characteristics
to fix or eliminate the brand of the firearms.
11. Methodology for analysis and
comparison
Visual Examination
The visual examination is carried out with ordinary light, allowed to fall at
various angles. Hand magnifier is useful and improves the visual
examination.
Visual examination of a cartridge case gives an idea about the positions
and the sizes of the firing pin, the breech face, the extractor, the ejector
and the chamber marks.
Stereomicroscopy
The stereomicroscopic examination of the bullets is useful for the
determination of their class characteristics. They facilitate the elimination
of the weapons of the other makes and models. The examination also
facilitates the comparison work. It gives the idea as to what to look and
where, in the comparison microscope.
12. Comparison Microscopy
It gives quick, efficient and presentable link/de-linking evidence present of
crime/test fired ammunition. The principle on which the instrument works is
simple. The comparison of the two sets of marks is facilitated if they are
magnified to the same extent and brought in juxtaposition in the same plane,
in an eyepiece or on a screen, simultaneously. A comparison microscope does
the same.
Side by Side (juxtapose) Match
Here the relevant corresponding portions of the crime and the test exhibits are
viewed side by side. The prominent marks are compared and the comparison
establishes the match or the non-match. The marks in the matching positions
are photographed.
The side-by-side match is useful for the non-striated impact marks from firing
pin indentations, the breech face marks, the chamber marks etc. on the fired
cartridges.
13. Composite Match
This technique is applied, almost invariably, in the study of all the striated
marks:
The firing pin scrapes on the bases of cartridges, the barrel marks on the
bullets and buckshots and the scratches, if any, produced by the breech faces,
the chambers, the extractors and the ejectors. The striated marks in the firing
pin indentations, if present, are studied/compared/photographed by this
process like other striated marks.
The corresponding positions of the crime and the test exhibits bearing the
striated marks are brought together at the dividing line. The test or the crime
exhibit is so manipulated that the striations on one side of the dividing line,
show continuity across the dividing line, if the striated marks are from the
same firearm.
14. Superimposition Technique
Not all comparison microscopes permit superimpositions of the test and crime marks. The
Leitz and the Projectina comparison microscopes are handy for this technique.
The images of the crime and the test exhibits are recorded side by side in half of the film (‘C’
and ‘T’). On the lower half of the film, the superimposed photograph is obtained. The images
here are so adjusted that the dividing line bisects the two images exactly, as in composite
photograph. Once this is achieved, the dividing line (prism) is moved to one side slowly until
the image in the field of view (on the screen) is only from one of the two exhibits (say, crime
exhibit). The image is now photographed by exposing it for three-fourth the normal time of
the exposure required. The exposure is stopped but the film is kept in the same position. The
image of the other exhibit (test exhibit) is obtained on the screen by moving the dividing line
(the prism) to the other side. This image is recorded on the same film over the first image,
exposing it for three-fourth the normal exposure time.
This second image is found superimposed on the first one, if the adjustment of the exhibits
and their images are proper and are not disturbed during the exposure process.
15. REFERENCES
Module 4 – Forensic Examination and Firearms Evidence (introduction-to-forensic-science-and-
criminology) – https://wilber-learndev.com/courses
firearms-and-toolmarks-overview.pdf from https://www.crime-scene-investigator.net
https://ncdoj.gov/crime-lab/firearms-and-tool-mark/
F I R E A R M I D E N T I F I C AT I O N I N T H E F O R E N S I C S C I E N C E L A B O R AT O R Y By Robert
M. Thompson – https://www.nist.gov/system/files/documents/forensics/Firearms_identity_NDAAsm.pdf
Different Types Of Marks Produced During Firing Process On Cartridge ppt – LAVANYA PS ASSISTANT
PROFESSOR SRINIVAS UNIVERSITY
Technical Procedure for Fired Cartridge Case/Shotshell Examination North Carolina State Crime Laboratory
– Firearms Section Issued by Firearms Technical Leader
How can a bullet be traced to a particular gun? (March 21, 2005) –
https://www.scientificamerican.com/article/how-can-a-bullet-be-trace/
EXAMINATION OF FIRED AMMUNITION COMPONENTS.pdf -
https://cfsmigrationdocs.blob.core.windows.net/