The use of firearms in crime is increasing dramatically across the world, but fortunately with forensics there are ways to track down the culprit by examining bullets and weapons used.

Rifling gives the bullet a signature marking that is unique to the weapon that fired it. Rifling is part of the manufacturing process of the firearm and serves to put a spin on the bullet, giving it a straighter trajectory. Rifling is lands and grooves that spiral down the gun barrel and when the bullet is fired the bullet's lead is forced against the grooves. This creates microscopic scratches on the bullet unique to the gun it was fired from.

This can be used to compare bullets and/or determine whether or not a bullet was fired from a particular gun. The suspect bullet and a bullet that has definitely been fired from the gun are placed under the microscope and compared. The unique scratches are examined, allowing is to determine whether or not a bullet was fired from a particular gun. This is clearly a useful method to forensic investigators.

We can also detect the trajectory of a bullet, which is the path a bullet follows. If a person is shot or a stray bullet is fire into a wall or object, we can determine in exactly what direction the bullet came from. As seen in many movies and television shows, we can follow the trajectory of the bullet.

However certain factors must be taken into account. When a bullet is fired it does not just move on straight until it hits something. Of course the bullet will eventually drop. Here is just when example of the rate at which a bullet may drop. This graph shows the drop of 2 bullet fired from 2 different rifles.

There are certain aspects that affect the trajectory of bullets. There are the likes of high or low velocity bullets available, meaning the trajectory is not always predictable.