CFC CFC Firearms, Ballistics & Tool Mark Examination 1 — Questions and Answers
Question 1: What does the term 'rifling' refer to in the context of firearm evidence?
- The act of searching a crime scene
- Spiral grooves cut inside a barrel that impart spin to a bullet (Correct answer)
- The mechanism that ejects spent cartridges
- The process of test-firing a recovered weapon
Correct answer: Spiral grooves cut inside a barrel that impart spin to a bullet
Rifling consists of helical grooves machined into a firearm barrel that cause the bullet to spin, improving accuracy and leaving unique striations on fired bullets.
Question 2: In ballistics examination, 'lands and grooves' on a recovered bullet are used to:
- Determine bullet composition
- Link the bullet to a specific firearm barrel (Correct answer)
- Identify the shooter's fingerprints
- Measure muzzle velocity
Correct answer: Link the bullet to a specific firearm barrel
Land and groove impressions on a bullet are produced by the rifling of a specific barrel and can be microscopically compared to test-fire bullets from a suspect weapon.
Question 3: Which technique do firearm examiners use to compare striations on two bullets under simultaneous magnification?
- Gas chromatography
- Comparison microscopy (Correct answer)
- Scanning electron microscopy (SEM) only
- X-ray fluorescence
Correct answer: Comparison microscopy
The comparison microscope allows an examiner to view two bullets or cartridge cases side by side simultaneously, enabling direct striation alignment comparison.
Question 4: Gunshot residue (GSR) analysis is used to detect the presence of which elements commonly found in primer residue?
- Iron, zinc, and copper only
- Lead, barium, and antimony (Correct answer)
- Mercury, cadmium, and tin
- Sodium, potassium, and chlorine
Correct answer: Lead, barium, and antimony
Traditional GSR analysis (via SEM-EDX) identifies characteristic particles containing lead, barium, and antimony originating from primer ignition.
Question 5: A fired cartridge case found at a crime scene can be linked to a specific firearm through marks left by the:
- Barrel rifling only
- Firing pin, breechface, and ejector (Correct answer)
- Trigger mechanism
- Magazine follower only
Correct answer: Firing pin, breechface, and ejector
The firing pin impression, breechface marks, and ejector/extractor marks on a cartridge case are compared microscopically to test-fired cases from the suspect weapon.
Question 6: What is the term for the unique microscopic surface characteristics on a tool that are transferred to the material it contacts, used in tool mark analysis?
- Latent features
- Class characteristics only
- Individual characteristics (Correct answer)
- Tooling artifacts
Correct answer: Individual characteristics
Individual characteristics are random, microscopic imperfections on a tool's surface that uniquely distinguish it from all other tools of the same class.
CFC CFC Firearms, Ballistics & Tool Mark Examination 1
What does the term 'rifling' refer to in the context of firearm evidence?