Determination of Range of Fire
Important information required in the investigation in cases related to firearms is to estimate the distance of a gun from the target hit by its projectile at the time of firing.
Determining the range of fire is based on the characteristics of the firearm wound, features of the wound that are caused due to the particles that are discharged from the firearm’s muzzle other than a bullet.
The distance of a gun from the target by studying patterns and residues left on the latter is discussed below.
Range of Fire is Determined by:
1. Shot Patterns
At close ranges, the shots emerging from a barrel of a shotgun travels with considerable force. The wads also get associated with the shot group up to a few centimetres from the muzzle. The shot separates progressively and spreads out. As there is an increase in the range, shots may spread to a wider area, but the impact would be less.
Due to this progressive change in the shot and the wadding pattern, it is possible to determine the distance of firing with considerable accuracy. The pattern is not affected by the type of the gun but also by its condition, and also the type and condition of ammunition can affect the pattern.
For this reason, the same gun and the same kind of ammunition are used to test fire at different measured ranges to match the pattern under question.
At the close range, i.e., within 15 cm, a circular entry wound is noticed if the muzzle is perpendicular to the target and elliptical if the muzzle end is at an angle.
2. Wad Distribution
Several wads are found in shotgun ammunition. They are propelled along with the other charge. They may enter the target up to three meters. If they don’t come across any obstruction, they can travel up to 5 meters. If the distance between the victim and the wads is known, the range can be determined.
3. Powder Pattern
All firearms, regardless of the type of projectile fired, release or discharge burnt, unburnt, and partially burnt powder materials from the muzzle end at the time of firing. These patterns are usually found on the victims’ clothing and around the area of the bullet hole in the close-range shooting.
4. Muzzle Pattern
When a firearm is discharged while pressed against the targets in cases of contact shot, an imprint of the muzzle is left on the target. In such wounds, the whole charge will enter into the target. No burning, blackening, and tattooing are observed around the entrance hole. Often the entrance hole will bear a tear on the cloth or skin in the form of a cross.
Scorching is caused on the surface of the target by flame or hot gases. Certain gases produced by the combustion of the powder charge generally catch fire on coming in contact with the oxygen of the air and produce a momentary flame.
The presence of scorching is a sure sign of close-range firing. The maximum scorching is often less than 15cms. It depends on the length of the barrel of the firearm and the quantity and age, and the nature of the powder charge.
Blackening is caused by the deposition of smoke produced by the combustion of the powder. But with the smoke, there may be black particles consisting of carbon and carbonaceous matters. The range of blackening is generally dependent on the gun used, the type of cartridge and the powder charge. It is seen up to 30cm
It is also known as stippling. This is usually caused by the impregnation of the unburnt or half-burned particles into the target. tattooing has a greater range of fire which is not more than 60cms
The information regarding the range of fire is useful in connection with self-defence pleas. It may also be useful in probing into a murder or suicide theory. It is often possible to estimate, with considerable certainty