PROJECTILES AND CARTRIDGES

FIREARMS

According to The Arms Act, 1959-

“Firearms” means arms of any description designed or adapted to discharge a projectile or projectiles of any kind by the action of any explosive or other forms of energy, and includes,—

(i) Artillery, hand-grenades, riot-pistols or weapons of any kind designed or adapted for the discharge of any noxious liquid, gas or other such things,

(ii) Accessories for any such firearm designed or adapted to diminish the noise or flash caused by the firing thereof,

(iii) Parts of, and machinery for manufacturing, firearms, and

(iv) Carriages, platforms and appliances for mounting, transporting and serving artillery;

PROJECTILES

Pellets, buck shots, shells, balls, flechettes, bullets are various types of projectiles which are meant to cause injury. These are propelled out by gases which are ejected by propellants when a weapon is fired. The construction materials, forms and sizes, and ballistics of these projectiles vary. Hardened lead alloy (Lead+ Antimony) is used to make the spherical projectiles. They can be employed as single projectiles, balls, or slugs, or in huge quantities, for examples, buckshot or pellets.

DIFFERENT TYPES OF BULLETS

1. Lead Bullet

Lead was the first projectile to be fired from a rifled weapon in the year 1849. Higher velocities and temperatures were achieved with the smokeless powders. Under those circumstances, lead bullets warped.

2. Paper-Patched Bullets

Paper was the most basic material for the jacket. Paper-patch bullets were the name for such projectiles. They were excellent. They did, however, leave pieces of paper in the barrel, which clogged it heavily and caused problems in later firings. The barrel required to be cleaned on a regular basis. The bullets made of paper patches didn’t last long.

3. Wire-Patched Bullets

A wire patch bullet is a lead bullet that has been securely wrapped in a copper or other material wire. The cable untangled itself during flight. Both range and aim were negatively impacted due to this. The bullet is packed around the wire in a tight envelope form.

4. Gas-Check Bullet

The strong metal coated base of the gas-check bullets protects the lead bullet from hot gases. Typically, the lid is composed of copper. The copper base is crimped on to the bullet with the help of lubrisizer. It enhances the bullet performance.

5. Electroplated Bullet

Lead bullets were electroplated with copper to prevent excessive deformation. The increased fouling of the barrel without a significant reduction in bullet distortion.

6. Metal Cased Bullet

In certain situations, the jackets have grease-filled cannelures that are crimped onto the cartridge case. As it passes through the barrel, the grease lubricates the bullet and minimises friction.

The following are examples of expanding bullets:

Dum-Dum Bullets: In these type of bullets, the tip was thinned by rubbing the tip of the jacket.

Soft or Silver Point Nose Bullets: The bullet’s tip is composed of a softer substance in this case. The materials utilised were brass and aluminium.

Hollow Point Bullets: Their tips are hollow. Pierced points bullets: On the top section of the jacket, there are linear cuts.

Belted Bullets: Near the middle, they have a thinner jacket. When the bullet enters the target, it fractures at this point.

Hard-Core Bullets: A hard-metal insert, made of steel or bronze, is placed in the cup of the jacket.

7. Armour-Piercing Bullet

An armour-piercing bullet is made up of a strong tungsten-chrome steel core point on one end and a soft tungsten-chrome steel tip on the other. It’s protected by a mild steel jacket with some gap between the core and the jacket. A specific filler alloy is used to fill the gap. When the jacket and filler strike the target, they generate enough heat to weaken the target material enough for the core to enter the target.

8. Tracer bullet

The tracer bullets follow their trajectories, or flight paths. After crossing a distance of around 100 metres, some people begin following the trail. The trail is evident as a brilliant red flame streak created by a specific composition (Barium peroxide and magnesium powder). Standard ammunition trajectories are studied using tracer ammunition.

9. Incendiary Bullet

When the incendiary bullet hits the target, it ignites. The ammunition is very hazardous and must be handled with utmost caution.

10. Boat-Tailed Bullet

The base end of boat-tailed bullets is tapered. At greater velocities, the conidial bullets were shown to produce significant air resistance. Air flow over the bullet was aided by tapering or boat-tailing, which reduced air resistance. The boat-tailing of bullets greatly enhances the accuracy and range of projectiles.

  • Spherical projectiles:

Hardened lead alloy (Lead+ Antimony) are used to make the spherical projectiles. There are three types:

  • Ball
  • Buck shots
  • Slugs

CARTRDIGE/SHELLS

The primer, propellant, wads, if any, and projectile charge are all housed in the cartridge casings or shells. They are made of a range of materials, including brass, paper, aluminium, steel, and plastics. In India, shotgun cartridges are usually packaged in paper cartridge boxes with a brass base. Cartridge cases with plastic tubes are now being manufactured by Indian Ordnance Factories.

Brass (70 percent copper, 30 percent zinc) is an excellent alloy for making shells. On a wide scale, it is the primary material utilised in the production of shells for rifles, handguns, and revolver ammunition. This is due to the ease with which the alloy may be stamped, drawn, and annealed. Furthermore, it is resistant to corrosion and weathering.

It has enough flexibility to fill the chamber when under pressure (obturation) and then return to its original size when the pressure is released. Only high-quality, pure brass is utilised for this purpose. Rimmed, semi-rimmed, rimless, or belted cartridge casings are available. They come in a variety of shapes and sizes, including straight, tapered, and bottleneck.

COMPONENTS OF A CARTRIDGE CASE

The casing, primer, powder, and bullet are the four components of an ammunition cartridge.

  1. The case: The container that keeps all of the components together is known as the casing. For pistols and rifles, the casing might be constructed of brass, steel, or copper. Shotgun “shells” consist of a plastic casing with a thin metal coating on the base.
  2. Primer: The primer is an explosive chemical substance that, when struck by a firing pin, ignites the gunpowder. Primer can be applied to the rim of the case (rim fire) or the middle of the case’s base (centerfire).
  3. Powder/Propellant: Gunpowder is a powdered combination of saltpetre, sulphur, and charcoal that is used to make explosives.

Bullet/Projectile: The cylindrical and pointed projectile that is ejected from the barrel, usually made of metal containing lead.

DIFFERENT TYPES OF CARTRIDGES

  • A Shotgun Shell

It is made up of three parts: a tube, a base, and a base wad. Shotgun shells are typically manufactured in two lengths: 2.5” (=63.5mm), 2.75” (=63.5mm). Brass is used for the base. The technique of producing the brass bases (cartridge heads) is identical to that of producing percussion caps or brass shells. Many layers of paper make up the basal wad.

  • Rifle Cartridge

Rifle cartridges come in a wide range of sizes and shapes. The most noticeable difference is in the firearm’s calibre, which is also an approximate estimate of the projectile’s diameter in the cartridge. The calibre designation is just indicative. The projectile’s actual diameter differs somewhat from the calibre specified.

The constructional characteristic of the cartridge shell is what distinguishes rifle cartridges. As a result, we have cartridges that are rimmed, semi-rimmed, rimless, or belted. The protrusion of the shell base extends beyond the tubular circle of the shell in the rimmed cartridges. The rim stops the shell from slipping into the chamber and aids the extraction claw in its work. It’s found in non-automatic weapons. The base diameter of rimless cartridges is the same as the cartridge case. They’re found in both automatic and semi-automatic guns. The lack of a rim allows the cartridges to travel more freely in the magazine and in the firing mechanism. Semi-rimmed cartridges have a construction that is in the middle of the two kinds. As a rim, it simply has a small protrusion of the base. The belted and semi-rimmed cartridges are advances in cartridge manufacturing that allow the same cartridge to be used in both automatic and non-automatic firearms. The shell in the belted cartridge features a bulge to prevent it from slipping into the chamber.

  • Revolver Cartridge

Revolver cartridges usually have a cylindrical rimmed casing and are center-fire. Bullets are made of a lead alloy (lead and tin in the ratio of 12:1 or lead alloy containing 1 percent antimony). In certain situations, they are jacketed. They feature a hollow base and a circular snout. The bullets have cannelures on them that are packed with beeswax for lubricating. In this application, propellants that burn quickly are employed.

  • Pistol Cartridge

Ammunition for pistols is comparable to that for revolvers. There are two major distinctions. Normally, pistol bullets are jacketed. Jacketed bullets for revolvers are also available from some manufacturers. The ballistics are comparable. Second, pistol cartridge casings are rimless, whereas revolver cartridge cases are rimmed.

  • Blank Cartridge

Blank ammunition is designed to make noise while being completely safe. There is no bullet or other substance in the cartridges that may serve as a projectile. Blank cartridges are available for a wide range of small guns. A weak pulverisable wad is placed over a normal empty cartridge case and an appropriate amount of rapid burning powder charge is added. The case’s mouth has been crimped. Blank cartridges are sometimes loaded with plastic bullets that disintegrate within 15 metres.

  • Rifle Grenade Cartridge

Ordinary or blank rifle grenade cartridges are made similarly to rifle grenade cartridges fired from.303 (or other calibre) rifles. The following are the key distinctions:

1. The over-powder wad is formed like a cup. By closing the barrel bore, it prevents gases from escaping.

2. To guarantee rapid pressure build-up, quick-burning powder is utilised.

  • Consumable Cartridge

The concept of a case less cartridge is appealing. It saves a significant amount of money in the production of both the rifle and the ammunition. H.I.T.P. is a unique high explosive composition combination used in the cartridge casing (High Ignition Temperature Propellant). This propellant produces a low temperature without reducing power. It resists being ignited by the external heat that builds up in the weapon chambers as a result of rapid firing. The following are some of the extra characteristics of the new propellant:

a) It produces more power per unit volume

b) It burns cleanly and produces less residues than traditional propellants.

  • Duplex Cartridge

In the United States, a duplex cartridge in.223 calibres has been released. Instead of one bullet, the cartridge has two. They’re designed to work together. One by one, they emerge from the muzzle. They struck the target at 300 metres in a one-meter-diameter circle.

SIGNIFICANCE OF FORENSIC BALLISTICS IN INVESTIGATION

>>By carefully examining the damage that a bullet suffers when it hits a hard surface, a forensic ballistics specialist may exactly estimate the distance, angle, and even the time when a pistol was discharged. Furthermore, forensic ballistics has the ability to aid investigators in determining the shooter’s identity. Examining any residue on the bullet and comparing it to that discovered on the suspect’s hand or body, the pistol used, or any other object collected from the crime scene is one approach to do this.

>>If forensic examiners find bullets at a crime scene, they can test-fire a suspect’s pistol and compare the markings on the crime scene bullet to the marks on the test-fired bullet.

SOURCES AND REFERENCES

Authored by:

AKHILA PRABHAKAR

BSc Forensic Science

Jain (Deemed-to-be-University)