Bullets for Beginners:
Guns are generally classified according to use, size and tradition. This various among the military services. The basic distinction is between small arms and artillery. Any gun below a distinction is between small arms and artillery. Any gun below a 20 millimeter bore size is generally classified as a small arm. An alternative term gaining increasing currency is “light arms”, to include individual and light.
Support Weapons:
The soldier’s individual weapons consist in most countries of an assault rifle in caliber 5.56 or 7.62 mm. Light support weapons consist of machine guns, single short grenade launchers and automatic grenade launchers. Machine guns are available in caliber 5.45, 5.56, 7.62, 12.7 and 14.5 mm. Single shot grenade launchers have a caliber of 40 mm, and generally fire a HE (High Explosive) grenade out to a maximum range of about 400 meters. Automatic grenade launchers have a caliber of 30 or 40 mm, firing ammunition is of a HE (High Explosive) or a HEDP (high explosive dual purpose) type with a maximum range amounts to 2200 meters.
Pistol:
A Pistol is a hand operated firearm having a chamber integral with or permanently aligned with the bore.
Revolver:
A Revolver is a hand operating firearm with a revolving cylinder containing chambers for individual cartridges.
Rifle:
A rifle is a shoulder firearm which can discharge a bullet through a rifled barrel 16 inches or longer. The spiral parallel grooves in the bore impact spin in the projectile, providing stability and extended range.
Carbine:
A Carbine has a barrel under 16 inches in length and is tipically used by cavalry, artillery, engineers or others who require a weapon for self-defense and emergencies. Accuracy and ballistics tend to be inferior to the full version of the rifles they are adapted from.

Assault Rifle:

Assault Rifles are capable of single shot or automatic fire using a short cartridge providing accurate fire and more controllable recoil force than a standard rifle cartridge. By reducing the cartridge case and propellant, the cartridges weigh less and soldiers can carry more. These shorter rifles were developed in response to the recognition that most firefights take place at ranges under 400 yards. The small size of the assault rifle and its ability to fire at up to 800 rounds per minute has led to it being adopted by various forces as a replacement for the submachine gun.

Machine Pistol:

A machine pistol is a firearm originally designed to fire, or capable of being fired, fully automatically by a single pull of the trigger. Submachine Gun – lightweight one man weapons capable of automatic fire, firing a low-powered pistol cartridge with limited range and accuracy.
Machine Gun:
A general purpose machine gun functions as either a squad light automatic weapon (light machine gun) when mounted on abipad and fired the shoulder, or as asustained fire long – range weapon (heavy machine gun) when mounted on a tripod or light vehicle and provided with an optical sight.
Bullets can be optimized for minimum time of flight, minimum dispersion, maximum retained kinetic energy, minimum cross wind sensitivity, minimum bassistic drop, maximum penetration, and limiting maximum range. For instance, a heavier bullet launched at lower muzzle velocity is a bullet designed to minimize cross wind sensitivity. As the bullet gets heavier, more of the projectile body can be dedicated to ogive length, reducing drag. Heavier, faster, lower drag is generally better, but with a fixed case volume, it is not possible to improve all of these attributes simultaneously. A bullet optimized for one parameter is often the worst solution for another important parameter. Optimizing one parameter requires compromise on others.
Small arms and machine gun projectiles are made of solid metal. However, projectiles of 20 mm guns and larger have many components. The form of the forward end of the projectile is an ogival curve (generated by revolving an arc of a circle about a chord) that is aerodynamically efficient. Behind the ogive, the projectile is cylindrical with the exception of the bourrelet, which is slightly larger than the diameter of the body to reduce the surface area (and thus the friction) of the projectile contacting the gun bore. Near the after end of the projectile is the rotating band, which is actually larger than gun bore diameter to engage the rifling grooves and seal the bore while supporting the aft end of the projectile. The rifling actually engraves the rotating band to ensure a gas-tight seal. Aft of the rotating band the cylindrical shape may continue to the base of the projectile od it may be tapered to a “boat tail.” A complete round of small-arms ammunition is known as a cartridge, and is made up of the following components:
Bullet: The bullet in general is cylindrical. The nose may be round, as in the cal, 50 bullet, or ogival as in all service rifles and machine gun bullets. The base may be square or boat tailed.
Types include the following:
• Armor-piercing bullets contain a core of hardened steel.
• Ball usually contains a slug of antimony-hardened lead except in case of the cal, .50, wherein the outer core is of soft steel.
• Tracer contains a lead slug, and a chemical composition in the rear.
• Incendiary bullets contain an incendiary composition.

Propelling charge: The propelling charge consists of a quanity of smokeless powder. The weight of the charge is not constant. It is adjusted for each powder lot to give the required velocity with pressure within the limits prescribed for the weapon in which it is fired. NATO Standard Ammunition:
Small Caliber ammunition types are differentiated by projectile tip identification paint, i.e., tracers are painted red or orange, armor piercing are black, dim trace are purple, etc.
CARTRIGE CASE

It provides the means in which components like primer, powder and a bullet are assembled in the form of a complete round. It is usually made up of cartridge brass (70% Copper+ 30% Zinc)
The functions of cartridge - case are
1. It holds in a single unit, the primer, powder and projectile.
2. When the firing takes place, the cartridge case expands and grips the inside of the chamber resulting in the sealing of the chamber to prevent rearward escape of gases. This is known as obturation.
3. It provides proof container for the propellant.
4. As regarding the shape of the base of the head of the cartridge may be rimmed, rimless, semi- rimmed, bolted or rebated.

Regarding the made of ignition, a cartridge may be pin-fire, rim-fire, center-fire. A primer is a small, sensitive explosive that on activation by a blow from firing pin gives off a flash of hot flame, which ignites the propellant charge. The primer compound in a center fire cartridge is placed in a cup like form made up of brass known as percussion cap.
Percussion cap contains priming mixture which when crushed between firing pin and anvil given hot piercing flame for the ignition of propellant. In general terms, a propellant is a solid material used to propel a bullet. Prior to 1842, black powder was practically the only propellant being used in firearms. Its composition is potassium nitrate 75%, sulphur 10% and charcoal 15% the era of modern high velocity ammunition stated with smokeless powder.
The basic constituents of smokeless powders are nitroglycerine and nitrocellulose. The components (pellets, shots, balls, bullets) of a cartridge intend to cause injuries.and which are hurled out by the gases produced in the discharge of a firearm are called projectiles.
Spherical Bullets
Conical Bullets
Bullets may be classified as spherical or conical. Bullets may be classified as lead alloy bullet, and Jacketed bullet. Wads are provided in between the bullet or shot charge and the propellant.