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Forensic Science Analysis > Firearms and Toolmarks Quiz 1 > Flashcards

Firearms and Toolmarks Quiz 1 Flashcards

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1
Q

Premise of Firearms and Tool Mark Analysis

A

Based on uniqueness.
Discipline supported by “Theory of Idenitfication”.
Based on examiner experience and training.

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2
Q

Common Types of Firearms

A

Pistols.
Revolvers.
Shotguns.
Rifles.

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3
Q

Antique Firearms

A

Not considered actual firearms today under Title 18.
More of a psychological deterrent than weapon.
Decreased velocity, rainbow trajectory (poor accuracy).

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4
Q

Practical Firearms

A

All modern day firearms.

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5
Q

Early Firearm Ignition Types

A

Matchlock.
Wheel Lock.
Flintlock.
All system attached to firearm itself.

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6
Q

Ignition System

A

How to light/ignite black powder.

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7
Q

Matchlock

A

Developed after simply using matches.

Attached a match which was lowered to ignite.

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8
Q

Wheel Lock

A

Spring powered wheel that lowered and created sparks.

Had a hard time functioning and rusted.

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9
Q

Flintlock

A

Flint against steel plate to create sparks.

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10
Q

Breakthrough Ignition Systems

A

Pin Fire.
Rim Fire.
Center Fire.

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11
Q

Pin Fire System

A

Combustion within projectile.
Firing pin.
If dropped, it can fire without a firearm.

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12
Q

Rim Fire System

A

Primer in rim of cartridge.
Hammer/firing pin attached to firearm.
Can still self-fire if enough pressure is put on primer.

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13
Q

Center Fire System

A

Used by most firearms today.
Cartridge holds all components of a live round of ammunition.
Combustion takes place within projectile itself.
See image.

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14
Q

Types of Ammunition

A

Pistol Load.
Hand Load.
Target Load.

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15
Q

Common Bullet Types

A 
Wadcutter.
Full Metal Jacket.
Jacketed Hollow Point.
Jacketed Soft Point.
Lead Round Nose.
Semi Wadcutter.
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16
Q

Rifling

A

Most valuable asset to firearms structure.
Spiral grooves cut into the bore of a barrel.
Stabilizes bullet.
Leaves opposite pattern on bullets.
Spins bullet, making it faster and more accurate.

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17
Q

Common Rifling Types

A

Conventional (cuts are seen easily).

Polygonal (smoother, harder to see).

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18
Q

Rifling Class Characteristics

A

Predetermined manufacture features.
Direction of twist.
Number of lands and grooves.

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19
Q

Rifling Individual Characteristics

A

Striations in grooves.

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20
Q

Caliber

A

Refers to nominal diameter of the bore within the firearm in inches (.357).
Ammunition: Nominal bullet diameter without the decimal in included (357).

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21
Q

Action

A

The working mechanism of the firearm.
May be broken down into action types (bolt, auto, lever, etc.)
Process of how weapon is fired (load, fire, eject, reload).

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22
Q

Projectile

A

An object propelled by force of rapid burning gas or other means.

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23
Q

Bullet

A

A non-spherical projectile for use in a rifled barrel.

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24
Q

Cartridge Case

A

The container that holds all the components which make up a live round of ammunition.

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25
Q

Propellant

A

The chemical composition within a cartridge that produces combustion and gases propelling the projectile.

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26
Q

Primer

A

The ignition component of a cartridge case.

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27
Q

Recoil

A

Effect of mechanism that creates a reaction due to pressure and force within firearm.
Often referred to as “bite” or “kick”.
Every firearm has recoil.

28
Q

Bullet Class Characteristics

A 
Width of lands and grooves.
Direction of twist.
Bullet type.
Caliber.
Weight in grains.
29
Q

Bullet Individual Characteristics

A

Striations in grooves.

Can look at ejection, extraction, and firing pin marks.

30
Q

Firearm Qualifications

A

Defined by Title 18.
Must have combustion reaction (not BB guns/pellet guns).
Any firearm muffler or firearm silencer.
Any destructive device (does not include antique firearms).

31
Q

Pistol

A

Earliest known was Colt 1911A.
Pro: Utilized recoil to eject, load, and cock hammer.
Con: More complicated design requires more practice.
Barrel length usually limited.

32
Q

Pistol Action Types

A

Semi-automaic, auto-loading, self-loading.

Double action only.

33
Q

Auto-loading

A

Fires, loads, extracts, ejects, and repeats (FLEER).

34
Q

Semi-automatic

A

All semi-automatic weapons utilize an additional pull of the trigger to perform operating cycle.

35
Q

Double Action Only (DAO)

A

Single pull fires, loads, extracts, ejects, and repeats.
Heavy trigger pull.
No external hammer.
Two actions performed by firearm.

36
Q

Single Action

A

External hammer has to be cocked prior to pulling trigger.

One action by firearm.

37
Q

Revolver Pro and Cons

A

Pro: Simple design, reliable, reasonable price.
Tend to be more accurate.
Con: Limited to six shots and slow to reload.
Trigger pull is greater.

38
Q

Revolver

A

Firearm having multiple chambers configured around an axis.
Utilize same mechanism or action to successfully discharge.
Single and double action.

39
Q

Rifle

A

Differ in length when compared to other hanguns, primarily in barrel length and presence of butt stock.
Most often utilized for hunting or military.
Pro: Much more powerful and accurate.

40
Q

Rifle Action Types

A

Often considered a long arm firearm consisting of barrel and stock which may contain one of many actions.
Most common action types are bolt action an lever action.

41
Q

Bolt Action

A

An action that requires manual loading, manual cycling, and manual bolt engagement in order to operate the firing mechanism.

42
Q

Lever Action

A

And action that requires the manual operation of an external lever below the receiver in order to operate the firing mechanism.

43
Q

Shotgun

A

Similar in appearance to rifles, however barrel is much larger.
Do not have rifling.
Long arm/big bore firearm consisting of receiver, stock, and barrel.
Pro: Can use different forms of ammunition (slug, pellets, buck shot).

44
Q

Shotgun Action Types

A

Vary depending on style of shotgun, however actions are similar to those in rifles (auto-loading, single action, and pump/slide action).

45
Q

Tool Mark Identification History

A

Earliest known was 1835 London, England.

46
Q

AFTE

A

Association of Firearms ad Toolmark Examiners.

47
Q

Theory of Identification #1

A

Opinions of common origin to be made when two surfaces are in “sufficient agreement” with one another.

48
Q

Theory of Identification #2

A

This sufficient agreement is related to the significant duplication of random tool marks as evidenced by corresponding patterns or combinations of patterns on surface contents.

49
Q

Theory of Identification #3

A

The current interpretation of individualization/identification is subjective in nature, founded on scientific principles and based on the examiner’s training and experience.

50
Q

Tool Mark Analysis as a Science

A

Ability to determine if a specific tool was used to create a specific mark or marks.

51
Q

Firearms Analysis as a Science

A

Ability to determine if a specific ammunition component was fired from, by, or in a particular firearm.

52
Q

Premise of Tool Mark Analysis

A
  1. Defining a tool.
  2. Understanding the manufacturing of various tools.
  3. Characterization of a tool.
53
Q

Definition of a Tool

A

Anything used to gain a mechanical advantage.

Classified by marks they exhibit during the manufacturing process or throughout their lifespan.

54
Q

Tool Class Characteristics

A

Size, shape.
Distance between discernable features (teeth, claws, blades, etc.).
Overall length.
These are measurable features.

55
Q

Tool Individual Characteristics

A

Many production techniques can produce individual characteristics.
Wear over time of machines that make tools.
Same happens in firearms manufacturing.
Random imperfection on tool surfaces.

56
Q

Tool Mark Features

A

Occur when two objects come into contact with each other.
Striated (striations).
Impressed (indentations).

57
Q

Striated Features

A

Have a series of ridges or linear marks.
Left by tool sliding or scraping across surface.
Follow motion of tool.
Screwdrivers, pliers, knives, extractor marks on a cartridge case.

58
Q

Impressed Features

A

Tools used forcefully against another surface.
Leaves impression or indentation.
Hammers, chisels, bolt cutters, breech bolt in firearm.

59
Q

Firearm Examination Process: Beginning

A

Begins when firearm is submitted with or without bullets or spent cartridge cases (ALL of which will be recovered at the crime scene).

60
Q

Examination Conclusions

A

Identification.
Elimination.
Inconclusive.

61
Q

Firearm Examination Process

A

Evidence (firearm) submitted.

Firearm tested.

62
Q

Firearm Examination Process: Testing

A

Firearm is test fired to recover KNOWN bullets and spent cartridges (ALL will be used for comparison).

63
Q

Level One Analysis

A

Class characteristic analysis.

Eliminations can occur here.

64
Q

Level Two Analysis

A 
Individual characteristic analysis.
Only execute level two if all discernable class characteristics DO agree.
More in-depth analysis is made of individual features.
65
Q

Eliminations

A

If all discernable class characteristics DO NOT agree.

66
Q

Complete Analysis

A

Must have both known and unknown samples to compare.

67
Q

Comparison Macroscope

A

Unit comprised of two compound microscopes connected by an optical bridge.
Tool mark holders.

Forensic Science Analysis (6 decks)

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