Firearms

25 03 2010

Q

An innocent citizen has been shot while he was on a walk. Two bullets have been shot towards him. The investigators gained the bullets that were pulled out of his body after death. The citizen is badly hurt, but has a very poor family. He has this weird insurance where he needs to find the shooter in order to get the money. How are the investigators supposed to find the criminal for this case?

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A

Firearm examiners can match a bullet to a specific gun. The bullets can be given to them to study.

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Firearm means portable gun. Firearm examiners can match a bullet to a specific gun by looking at the shape of the bullet that has been shot.

This gun is semiautomatic hand gun. It fires a single cartridge.

To shoot…

1.Trigger has to be pulled

2. The hammer is triggered to hit the firing point

3. The firing pin hits cartridge, releasing the bullet.

This is a picture of the cartridge and its parts.

There are a few characteristics of bullets that can be used to distinguish them. There are class characteristics, specific for a certain brand or type of firearm, and individual characteristics, specific for an individual fire.

Class characteristics

  1. Conventional rifling
  2. Polygonal rifling

1. Conventional rifling

Conventional rifling is a traditional rifling technique that makes deep, easily visible grooves on the surface of the bullet.

2.Polygonal rifling

Polygonal rifling is a technique that leaves smooth rifling impressions, that can be really har

Individual characteristics

  1. Rifling number
  2. Rifling direction
  3. Striations

1. Rifling number

Rifling number is the number of grooves in the rifled barrel. The rifling number can be determined by rotating the bullet and counting the number of the grooves left on the surface.

2. Rifling direction

Rifling grooves are spiral either to left or right, or right or left, making the spin clockwise or counterclockwise int he air when the bullet is floating in the air. The direction of rifiling is ere

3. Striations

Striation are microscopic scretches ont eh surface inside the rifling impressions. No two firearms will produce exactly

* Rifling impression

Rifling impressions are impressions left on the surface of a bullet after it has been fired from a firearm with a rifled barrel.

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