Forensics Ballistics review

What is the term for loading a gun from the front?

Muzzle Loading

What is structure A?

Groove

A gun that needs two hands to fire is considered what kind of gun?

A Long Gun

Who discovered the comparison microscope?

Gravelle with the assistance of Goddard (both credited)

What are the four parts of a cartridge?

Primer, Gun Powder, Casing, and Bullet

A firearm releases one bullet on the pull of the trigger and then loads the next round into the gun from a clip. What type of weapon is this?

Semi-Automatic

What type of device was used to fire muzzle loading muskets?

Matchlock

What is the FIRST and most IMPORTANT rule of processing a firearm when finding evidence?

Assume the firearm is LOADED and NOT SAFE.

How do you measure caliber?

Diameter of the barrel from land to land.

 When we say a gun is a “22”, what specifically does that tell you?

The caliber; the diameter of the gun barrel is .22 inches across

Where should you hold the gun when collecting evidence?

The grip

What color does the modified griess test turn when testing for GSR if there is a positive result (residue is present)?

Red – Orange (nitrate)

What is structure A below?

Land Impressions

What is the difference between EXTRACTOR and EJECTOR marks?

- Both are MINUTE SCRATCHES

      Extractor marks are made when the cartridge is loaded into the chamber by the extractor, ejector marks are made when the cartridge is removed from the chamber by the ejector

What nation invented gun powder?

The Chinese

What is the correct order?

  A: Explosion pushes bullet from casing into barrel 

      B: Bullet follows lands and grooves and spirals out 

      C: Primer sparks through a hole

      D: Firing pin hits base of cartridges and ignites primer

D, C, A, B

What is the size of the entrance hole compared to the exit hole?

Smaller

When a cartridge slams backward and strikes the back of the gun, it makes a mark. What is the name of this mark?

 Breechblock Mark

What color does the sodium rhodizonate test turn when testing for GSR if there is a positive result (residue is present)?

Brown-Pink (barium) OR scarlet Red (Lead)

For rifling to be individual evidence you must have what?

A comparison bullet

What color does the treated paraffin wax turn when testing for GSR if there is a positive result (residue is present)?

Blue (nitrate)

Name three types of marks that could be individual evidence.

Land/Groove Impressions, Firing Pin Impressions, Extractor/Ejector Marks

What can fibers on a wound tell you?

Direction of penetration

What do investigators fire a suspect’s gun into to acquire a comparison bullet?

Water tank or Gel tank

 What wound can you find GSR on?

Entrance

According to the notes, would a 22 or 45 caliber bullet be more likely to stay in the body?

22!

What is this photo and example of?

Tattooing/muzzle imprint

How does stippling happen?

 When the wound is caused by a firearm held touching or close to the skin.

Why do entrance and exit wounds not always line up?

They tend to hit structures in the body and redirect.

What color does the Harrison Gilroy test turn when testing for GSR if there is a positive result (residue is present)?

Orange (Antimony) OR Red (Lead and barium)

As the shooter moves farther away from the victim what happens to GSR?

Decreases