Lesson 1 - Firearm Basics

Firearm Basics

Revolver

Shotgun
Pistol

Rifle

 

 

 

 

 

 

 

 

 

 

 

The first forensic firearm identification occurred in England in 1835 when the distinctive markings on a bullet taken from a victim were matched with a bullet mould belonging to the suspect. When confronted with this evidence, the suspect confessed to the crime.

Internal, External, and Terminal Ballistics

Ballistics is a science that deals with the motion, behaviour, and effects of projectiles (such as bullets, rockets, and missiles). Forensic ballistics involves the science of analyzing the motion, behaviour, and effects of a bullet fired from a gun. The study of forensic ballistics has three sub-categories: internal ballistics, external ballistics, and terminal ballistics.

1.   Internal ballistics is the study of the evidence produced inside a firearm when a bullet or round is fired. This includes the study of firearm mechanisms, gun barrel manufacturing techniques, factors influencing the internal gas pressure within a particular firearm, and firearm recoil. The most common types of internal ballistics involve:

      • examining the working mechanisms of firearms to determine the cause of accidental discharges.
      • examining homemade devices (sometimes called zip guns) to determine whether they are capable of discharging ammunition effectively.
      • comparing fired bullets and cartridge cases to determine whether a particular firearm was used.

2.  External ballistics is the study of the bullet's flight from the moment it leaves the muzzle of the firearm's barrel until it strikes a target. The two most common types of external ballistics forensic examinations involve

      • calculating and reconstructing of bullet trajectories
      • determining the maximum range of a given bullet

3.  Terminal ballistics is the study of a bullet’s effect on the target or the counter effect of the target on the bullet. Wound ballistics is a form of terminal ballistics in which the target is a human or an animal. Common types of terminal ballistics forensic examinations include:

    • determining the distance between firing point and target
    • establishing whether a particular bullet caused the wound in question
    • determining the calibre and type of bullet that caused damage or, in the case of a human victim, a gunshot wound
    • identifying the entry and exit points of a bullet in a static target or human body
    • examining ricochet possibilities of targets and fired bullets

If a gun is fired into the air, the bullet may travel as much as two kilometres high depending on the angle of the shot and the power of the gun. When a bullet reaches its highest point, it begins to fall. Bullets are aerodynamic; therefore, a bullet falling back to earth can be quite lethal if it hits someone.

In an open rural area with few people, the chance of a bullet that has been fired into the air hitting someone is remote. In crowded cities, however, the probability of being hit by a stray bullet that has been shot into the air rises dramatically.

                                                                                         - How Stuff Works: http://www.science.howstuffworks.com