Most of us watch bullets being fired from the guns in many action movies. Ofcourse for us, buying a gun is subjected to the country's federal laws. Whether you own one or not, if you have ever wondered how bullet gets it speed when gun is fired, Then this is what that happens in the background.
There are many sizes of guns right from the smallest Miniature Revolver C1ST to the largest Schwerer Gustav( Railway gun). They all have bullets of corresponding sizes. Let us know in brief how bullets evolved before knowing how bullet gets it's speed.
"Bullet" is derived from the French word boulette which roughly means little ball. Originally, bullets were made out of stone or purpose-made clay balls used as sling ammunition, as weapons and for hunting. Eventually as firearms were developed, these same items were placed in front of a propellant charge of gunpowder at the end of a closed tube. As firearms became more technologically advanced, from 1500 to 1800, bullets changed very little. They remained simple round (spherical)lead balls, called rounds, differing only in their diameter.
The original musket bullet was a spherical lead ball smaller than the bore, wrapped in a loosely fitted paper patch which served to hold the bullet in the barrel firmly upon the powder. Bullets that were not firmly upon the powder, when fired caused the barrel to explode, with the condition known as a short start.
Later Square bullets, invented by James Puckle and Kyle Tunis, were briefly used in one version of the Puckle gun. The use of these was soon discontinued due to irregular and unpredictable flight patterns.
Later the pointed bullets are developed and were resisted to be used at the beginning for various reasons and were later accepted. The next important change in the history of the rifle bullet occurred with invention of the copper-jacketed bullet, which is an elongated bullet with a lead core in a copper jacket.
The surface of lead bullets fired at high velocity may melt due to hot gases behind and friction with the bore. Because copper has a higher melting point, and greater specific heat capacity and hardness, copper-jacketed bullets allow greater muzzle velocities.
Bullet designs have to solve two primary problems. In the barrel, they must first form a seal with the gun's bore.The bullet must also engage the rifling without damaging or excessively fouling the gun's bore, and without distorting the bullet. These interactions between bullet and bore are termed internal ballistics. Bullets must be produced to a high standard, as surface imperfections can affect firing accuracy.
A bullet generally consist of 5 main parts. They are:
- Bullet
- Casing
- Propellant
- Rim
- Primer
The bullet is what that actually hits the target. Propellant is the explosive that gives necessary force to the bullet to hit the target, it occupies about two thirds of a typical bullet's volume. Casing holds all parts together. Primer is like a fuse which ignites the propellant and rim provides the extractor on the firearm a place to grip the casing to remove it from the chamber once fired.
When the trigger is pulled a spring mechanism hammers a metal firing pin into the back end of the bullet, igniting the small explosive charge in the primer. The primer then ignites the propellant, as the propellant chemicals burn, they generate lots of gas very quickly. The gas shoots from the back of the bullet, increasing the pressure behind it, and forcing it down the gun barrel at extremely high speed of around 300 m/s. The speed of bullet depends on various factors. here is video to help you understand better.
The primer is a metal cup containing a primary explosive inserted into a recess in the center of the base of the cartridge. A primary explosive is an explosive that is extremely sensitive to stimuli such as impact, friction, heat, static electricity, or electromagnetic radiation. A relatively small amount of energy is required for initiation. As a very general rule, primary explosives are considered to be those compounds that are more sensitive than PETN. Upon being struck with sufficient force, a primer reacts chemically to produce heat which ignites the main propellant charge and fires the projectile (bullet).
The propellant chemicals in a handgun bullet are not designed to explode suddenly all at once, that would blow the whole gun open and very likely kill the person firing it. Instead, they are supposed to start burning relatively slowly, so the bullet moves off smoothly down the gun. They burn faster as the bullet accelerates down the barrel, giving it a maximum "kicking" force just as it comes out of the end. As the bullet emerges, the whole gun recoils because of a basic law of physics called "action and reaction" or Newton's third law of motion. When the gas from the explosion shoots the bullet forwards with force, the whole gun jolts backwards with an equal force in the opposite direction. The propellant used could be either gunpowder or cordite.
Previously revolvers used to be the hand guns, now we have semi automatic pistols. The two videos show the animation of how they work.
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References:
- http://en.wikipedia.org/wiki/Bullet
- http://en.wikipedia.org/wiki/Schwerer_Gustav
- http://en.wikipedia.org/wiki/Primer_(firearm)
- http://en.wikipedia.org/wiki/Centerfire_ammunition#Centerfire_primers
- http://en.wikipedia.org/wiki/Internal_ballistics
- http://en.wikipedia.org/wiki/Explosive_material#Primary_explosive
- http://www.sadefensejournal.com/wp/?p=1241
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