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Firearm

2007 Schools Wikipedia Selection. Related subjects: Military History and War

   An assortment of modern handheld firearms using fixed ammunition,
   including military assault rifles, a sporting shotgun (fourth from
   bottom), and a tactical shotgun (third from bottom).
   Enlarge
   An assortment of modern handheld firearms using fixed ammunition,
   including military assault rifles, a sporting shotgun (fourth from
   bottom), and a tactical shotgun (third from bottom).

   A firearm is a weapon that fires either single or multiple projectiles
   propelled at high velocity by the gases produced through rapid,
   confined burning of a propellant. This process of rapid burning is
   technically known as deflagration. In older firearms, this propellant
   was typically black powder, but modern firearms use smokeless powder,
   cordite, or other propellants. Most modern firearms (with the notable
   exception of smoothbore shotguns) have rifled barrels to impart spin to
   the projectile for improved flight stability.

   The term gun is often used as a synonym for firearm, but in specialist
   use has a restricted sense—referring only to an artillery piece with a
   relatively high muzzle velocity and a relatively flat trajectory, such
   as a field gun, a tank gun, an anti-tank gun, or a gun used in the
   delivery of naval gunfire. Guns are distinct from howitzers and
   mortars, which have lower muzzle velocities and higher trajectories.
   Hand-held firearms, like rifles, carbines, pistols and other small
   firearms are rarely called "guns" in the restricted sense among
   specialists.

   Accordingly, the term machine gun is not a misnomer. Although such
   firearms fire small caliber ammunition (generally 14.5 mm or smaller),
   they nevertheless have a flat projectile trajectory and a beaten zone,
   just like any other gun. Machine guns can be deployed in direct and
   indirect fire missions in a manner similar to artillery guns.
   Additionally, machine guns are crew served firearms, requiring the
   services of more than one crewman, just like any other gun. Generally,
   an automatic firearm designed for a single user is referred to as an
   automatic rifle. The discrimination between a machine gun and other
   firearms is deemed by the ATF (Bureau of Alcohol Tobacco and Firearms)
   as a firearm which dispenses more than one round with a single
   manipulation of the firing device.

   In recent centuries, firearms have become the predominant weapons used
   by mankind. Modern warfare since the late Renaissance has relied upon
   firearms, with wide-ranging effects on military history and history in
   general. The Moors introduced firearms in Europe, when Iberia was under
   their rule. This created a whole new kind of battle, which molded
   modern-era armies.

   For handguns and long guns, the projectile is a bullet or, in
   historical cannons, a cannonball. The projectile is fired by the
   burning of the propellant, but in small arms rarely contains explosives
   itself. For modern artillery the projectile is a shell, which nearly
   always contains explosives.

   A distinction is sometimes made between the projectile itself as the
   weapon and the firearm as a weapons platform. In some cases, the
   firearm can be used directly as a weapon without firing a projectile,
   although this is virtually always a secondary method of attack. For
   example, arms such as rifles, muskets, and occasionally submachine guns
   can have bayonets affixed to them, becoming in effect a spear or pike.
   With some notable exceptions, the stock of a long gun can be used as a
   club. It is also possible to strike someone with the barrel of a
   hand-held gun or grasp it by the barrel and strike someone with the
   butt. This is called "pistol-whipping".

   A problem for firearms is the accumulation of waste products from the
   partial combustion of propellants, metallic residue from the bullet
   itself, and small flecks of the cartridge case. These waste products
   can interfere with the internal functions of the firearm. As a result,
   regularly used firearms must be periodically partially disassembled,
   cleaned and lubricated to ensure the firearm’s reliability.

   Firearms are sometimes referred to as small arms. Small arms are
   firearms which can be carried by a single individual. According to
   international conventions governing the Laws of War, small arms are
   defined (with some exceptions) as firearms which fire a projectile not
   in excess of 15mm (0.60 inches) in diameter. Small arms are aimed
   visually at their targets by hand using optical sights. The range of
   accuracy for small arms is generally limited to about one mile
   (1600 m), usually considerably less, although the current record for a
   successful Sniper attack is slightly more than 1.5 miles (2.4 km).
   Artillery guns are much larger than these firearms, mounted on a
   movable carriage, having bores of up to 18 inches (46 cm) and possibly
   weighing many tons. Artillery can be accurate at ranges of up to about
   26 miles (42 km) and, with some notable exceptions (e.g., tank guns),
   are aimed using altitude/azimuth settings. Strictly speaking, such
   weapons are not firearms.
   Interior of the barrel of a 75 mm World War I artillery piece.
   Enlarge
   Interior of the barrel of a 75 mm World War I artillery piece.

History

   Gunpowder was invented in China around the 9th century AD. Chinese
   first used gunpowder in warfare in 904, as incendiary projectiles
   called "flying fires." "Fire lances", gunpowder-propelled arrows, were
   used in China from at least 1132. In 1221, cast iron bombs thrown by
   hand, sling, and catapult are mentioned. Somewhere around 1249, the
   Chinese of the Song Dynasty began to load early gunpowder in the middle
   of thick bamboo as a projection firearm, firing clay pellets like a
   shotgun. At some point in the late fourteenth century (the earliest
   certain example is dated 1332) they replaced the bamboo with bronze.
   Additionally, the Chinese and Mongols took up the use of "true"
   gunpowder instead of the slower-burning older mixture - which made this
   early cannon - known as the Huochong - more reliable and powerful.
   During wartime, the Chinese used the early gunpowder weapons in defence
   against the Mongols, and the weapon was taken up by the Mongol
   conquerors later. Many of the earliest weapons seem to primarily have
   functioned as psychological weapons, a trait gunpowder arms would keep
   for a long time.

   During the time of the Song dynasty 11th-13th century CE, portable
   firearms were introduced in the form of bronze tubes (based on the
   firelance designs) that fired rounds iron balls.

   Around the late 1400s in Europe, smaller and portable hand-held cannons
   were developed, creating in effect the first smooth-boore personal
   firearm. As the centuries progessed, these hand-held cannons evolved
   into the flintlock rifle, then the breech loader and finally the
   automatic.

   Breech loaders became practical in the 1860's when metallurgy developed
   sufficiently that brass could be worked into "fixed ammunition".
   (Previously each round was custom made as needed; the shooter poured
   loose powder down the barrel, used leather or cloth for wadding if time
   allowed, selected a suitable projectile (lead ball, rocks, arrow, or
   nail), then seated the projectile on top of the powder charge by means
   of a ramrod. Performance was erratic.) Fixed ammunition combined a
   primer, the pre-measured charge, and the projectile in a water
   resistant brass "cartridge case". Most important, the soft brass
   expanded under pressure of the gas to seal the rear end of the barrel;
   which prevented the shooter from being maimed by escaping high pressure
   gases when he pulled the trigger.

   A repeating firearm or "repeater" is a firearm that can be fired more
   than once between loading, more commonly known as a semi-automatic
   firearm if fed from a tube or magazine, or a revolver if fed from a
   rotating cylinder.

   Early firearms had to be cocked before each shot.

   Double-action revolvers could be fired two ways. You could cock it and
   fire it (now called "single action") or you could fire it by pulling
   the trigger. Single action tended to be more accurate because the
   trigger pull was shorter and lighter.

   Self-loaders are firearms that use some of the discharge energy to
   reload the firearm. These are also called semi-automatics. These are
   typically fed from a tube or detachable magazine, also referred to as a
   “clip” which is actually a reference to a reloading device used in
   earlier firearms mostly rifles, but also in pistols.

   Automatics (also called full autos, machineguns, or machine pistols)
   were not practical until the development of smokeless powder in the
   late 1800's. Black powder caused too much fouling of the mechanism to
   allow automatics or self-loaders to be reliable.

Small arms

Handgun

   19th century pistol from the French Navy.
   Enlarge
   19th century pistol from the French Navy.

   The smallest of all small arms is the handgun, which is perhaps more
   commonly called a " pistol". There are three common types of handguns:
   single-shot pistols (more common historically), revolvers, and
   semi-automatic pistols. Revolvers have a number of firing chambers in a
   revolving cylinder; each chamber in the cylinder is loaded with a
   single cartridge. Semi-automatic pistols have a single fixed firing
   chamber and a removable magazine so they can be used to fire several
   shots. The Italian-made Mateba revolver is a rare "hybrid," a
   semi-automatic revolver. Each press of the trigger fires a cartridge
   and rotates the cylinder so that the next cartridge may be fired
   immediately.
   Modern version of Colt's famous "Single Action Army" revolver.
   Enlarge
   Modern version of Colt's famous " Single Action Army" revolver.

   Handguns differ from rifles and shotguns in that they do not have
   shoulder stock and are designed to be fired with one or two hands.
   While the term 'pistol' defines any handheld firearm, it is common to
   refer to a single-shot or auto-loading handgun as a 'pistol' and a
   revolver as a 'revolver'.
   M1911, US Army designation for Colt's .45 semi-automatic.
   Enlarge
   M1911, US Army designation for Colt's .45 semi-automatic.

   The term 'automatic pistol' is sometimes used and is somewhat
   misleading in that the term 'automatic' does not refer to the firing
   mechanism, but rather the reloading mechanism. When fired, an automatic
   pistol uses recoil and/or propellent gases to automatically extract the
   spent cartridge and insert a fresh one from a magazine. Usually (but
   not always) the firing mechanism is automatically cocked as well. An
   automatic pistol fires one shot per trigger pull, unlike an automatic
   firearm such as a machine gun, which fires as long as the trigger is
   held down. There are, however, some fully automatic handguns (often
   referred to as machine pistols) so, to avoid such ambiguity and
   confusion, the term semi-automatic (or semiautomatic) is preferred when
   referring to a firearm that fires only one shot per trigger pull.

   Prior to the 19th century, all handguns were single-shot muzzleloaders.
   With the invention of the revolver in 1818, handguns capable of holding
   multiple rounds became popular. At the end of the 20th century, most
   handguns are semi-automatic, although revolvers are still widely used.
   Generally speaking, military and police forces use automatic pistols
   due to their high magazine capacities (10, 15, 17 or, in some cases, up
   to 25+ rounds of ammunition) and ability to rapidly reload by simply
   removing the empty magazine and inserting a new one. Handgun hunters
   use revolvers almost exclusivly due to the fact that hunting cartridges
   are generally much more powerful than autopistol cartridges and the
   simplicity and durability of the revolver design is well-suited to
   them. Lawfully armed citizens carry either type, depending on personal
   preference.

   Handguns come in many shapes and sizes. For example, the " derringer"
   (a generic term based on the mid-19th-century "Deringer" brand name) is
   a very small, short-barreled handgun, usually with one or two barrels
   but sometimes more (some 19th-century derringers had four barrels) that
   have to be manually reloaded after being fired. Carefully matched
   single-shot duelling pistols were used primarily in the 18th and 19th
   centuries to settle serious differences among "gentlemen": Alexander
   Hamilton and Aaron Burr are probably the most prominent Americans who
   used duelling pistols to settle their differences. Fully automatic,
   relatively easily concealed machine pistols, such as the MAC-10, GLOCK
   18, and the Beretta 93R, were a late 20th-century development.

   Handguns are small and usually made to be easily concealed, thus making
   them a very common choice for personal protection. In the military,
   handguns are usually issued to those who are not expected to need more
   potent (and more expensive) firearms, such as general and staff
   officers, and to those for whom there is no room for a full-sized
   rifle, such as armored vehicle and air crews. In this last role, they
   often compete with the carbine, which is also usually issued to
   airborne infantry because of its small size. Outside the military,
   handguns are the usual armament for police (in those jurisdictions
   where police are armed) and, where legal, for private citizens. Private
   citizens in most jurisdictions usually carry only concealed handguns in
   public except when hunting, since an unconcealed firearm would attract
   undue attention, and would therefore be less secure, although there are
   significant numbers of states in the US that continue to permit open
   carry of handguns. In the United States, the number of states which
   permit concealed carry has recently grown to over 35, and several
   states have well over 200,000 permit holders. Despite Second Amendment
   constitutional roots in the United States, the concept of citizens
   carrying a concealed firearm for self-defense is often a contentious
   political issue; see gun politics for more information.

   Handguns are also used for many sporting purposes and hunting, although
   hunting usage is usually viewed as somewhat atypical due to the limited
   range and accuracy of handguns. Some hunters however do their hunting
   in areas of dense cover where long guns would be awkward or relish the
   increased challenge involved in handgun hunting due to the necessity of
   approaching the game animal more closely. Small-bore (e.g., .22 caliber
   rimfire) handguns have long been very popular for competitive target
   shooting, partially due to the low cost of both the firearms and the
   ammunition, and there is also a rapidly growing number of sporting
   competitions for larger calibers.
   United States Springfield 1903 rifle.
   Enlarge
   United States Springfield 1903 rifle.

Long guns

   Most modern long guns are either rifles or shotguns. Historically, a
   long smoothbore firearm was known as a musket. A rifle has a rifled
   barrel that fires single bullets, while a shotgun fires packets of
   shot, a single slug, a sabot, or a speciality round (tear gas, Bolo
   Shell, lead powder, etc.). Rifles are often built for accuracy and long
   range and are aimed, while shotguns are usually designed to quickly hit
   a moving target and are instead "pointed". Rifles have a very small
   impact area but a long range and high accuracy. Shotguns have a large
   impact area with considerably less range and accuracy. However, the
   larger impact area can compensate for reduced accuracy, since shot
   spreads during flight; consequently, in hunting, shotguns are used for
   flying game.

   Rifles and shotguns are commonly used for hunting and often to defend a
   home or place of business. Usually, large game are hunted with rifles
   (although shotguns can be used—deer hunting with a shotgun is possible
   with the use of buckshot, sabots or slugs) while birds are hunted with
   shotguns. Shotguns are sometimes preferred for defending a home or
   business due to their wide impact area, multiple wound tracks (when
   using buckshot), shorter range, and reduced penetration of walls, which
   significantly reduces the likelihood of unintended harm, although the
   handgun is also commonly preferred.
   One pump-action and two semi-automatic shotguns, 20 boxes of shotgun
   shells, a target thrower, and three boxes of clay targets.
   Enlarge
   One pump-action and two semi-automatic shotguns, 20 boxes of shotgun
   shells, a target thrower, and three boxes of clay targets.

   There are a variety of types of rifles and shotguns based on the method
   they are reloaded. Bolt-action and lever-action rifles are manually
   manipulated. Manual manipulation of the bolt or the lever causes the
   spent cartridge to be removed, the firing mechanism recocked, and a
   fresh cartridge inserted. These two types of action are almost
   exclusively used by rifles.

   Slide-action (commonly called 'pump-action') rifles and shotguns are
   manually cycled by shuttling the foregrip of the firearm back and
   forth. This type of action is typically used by shotguns, but several
   major manufacturers make rifles as well.

   Automatic and semi-automatic rifles and shotguns both use either recoil
   or propellent gases to operate the firing mechanism that extracts and
   loads cartridges and recocks the firing mechanism. Semi-automatics
   employ an interrupter mechanism to only fire one shot per pull of the
   trigger, while full-automatics do not have such a system and fire
   multiple shots with a single pull of the trigger.

   Both rifles and shotguns also come in break-action varieties that do
   not have any kind of reloading mechanism at all but must be hand-loaded
   after each shot. Both rifles and shotguns come in single- and
   double-barreled varieties; however due to the expense and difficulty of
   manufacturing double-barreled rifles are rare. Double-barreled rifles
   are typically intended for African big-game hunts where the animals are
   dangerous, ranges are short, and speed is of the essence. Very large
   and powerful calibers are normal for these types of guns.

   Rifles have been in nationally featured marksmanship events in Europe
   and the United States since at least the 18th century, when rifles were
   first becoming widely available—one of the earliest purely "American"
   rifle-shooting competitions took place in 1775, when Daniel Morgan was
   recruiting sharpshooters in Virginia for the impending war with Great
   Britain. In some countries, rifle marksmanship is still a matter of
   national pride. Some specialized rifles in the larger calibers are
   claimed to have an accurate range of up to about one mile (1600 m),
   although most have considerably less effective range. In the second
   half of the 20th century, competitive shotgun sports became perhaps
   even more popular than riflery, largely due to the motion and immediate
   feedback in activities such as skeet, trap and sporting clays.
   An 1865 Gatling gun.
   Enlarge
   An 1865 Gatling gun.

Machine guns

   A machine gun is a fully automatic firearm used almost exclusively by
   the military. Although not widely fielded until World War I, early
   machine guns were being used by the military in the late 19th century
   (e.g., the Gatling gun). They are primarily defensive firearms, mainly
   because of the difficulties involved in moving and placing them, and
   their inherent lack of accuracy. In contrast, light machine guns (such
   as the U.S. military's M249 Squad Automatic Weapon (SAW) and the M60
   machine gun, both of which are small-caliber firearms) are often
   wielded by a single infantryman; they provide a high rate of fire
   typically used as either suppressing fire or covering fire during
   infantry movement. Machine guns are also often mounted on vehicles or
   helicopters, and have often been used since World War II as offensive
   firearms in fighter aircraft and tanks (e.g., for air combat or
   suppressing fire for ground troop support).
   A replica of the 1928 Thompson submachine gun.
   Enlarge
   A replica of the 1928 Thompson submachine gun.

   A submachine gun is a machine gun that fires cartridges that would
   otherwise be used in a handgun. Probably the most well-known example of
   a submachine gun is the Thompson submachine gun (the "Tommy Gun" of
   gangster movies), which fires .45 ACP cartridges. Other well-known
   examples are the Israeli Uzi, the British Sten, and the German MP5, all
   of which implement the 9 mm Luger Parabellum, and the U.S.'s M3 Grease
   Gun which fires .45 ACP.

   In United States law, a Machine Gun is defined (in part) by The
   National Firearms Act of 1934, United States code Title 26, Subtitle E,
   Chapter 53, Subchapter B, Part 1, § 5845 as:

   "... any firearm which shoots ... automatically more than one shot,
   without manual reloading, by a single function of the trigger."

   In the United States, purchases of machine guns manufactured after 1986
   by civilians were banned by the Firearm Owners Protection Act (FOPA),
   passed in that year. Importation of machine guns for civilian sale in
   the U.S. was banned by the Gun Control Act of 1968. Machine guns
   manufactured prior to 1986 or imported prior to 1968 can still be
   legally transferred to civilians who pay a substantial tax to the BATFE
   and pass a background investigation. In addition, "transferable"
   machine guns must have been registered with the BATFE prior to 1986.
   Machine Gun parts kits (which do not include a functional receiver) can
   be transferred without restriction. Permission must be received from
   BATFE to move a machine gun between states.
   Kalashnikov's AK-47 assault rifle.
   Enlarge
   Kalashnikov's AK-47 assault rifle.

   One of the most popular, most produced and most used automatic rifles
   in the world is the Soviet AK-47. It served in the Soviet army as
   standard infantry firearm issue, as well as in many other east-block
   states, and is still used as standard military equipment in some former
   Warsaw Pact countries. As over 100 million AK-47s were manufactured, it
   has also become the firearm of choice worldwide for many criminal or
   terrorist organizations . A semi-automatic version of this firearm is
   available in many locales where fully automatic firearms are not
   available.

Loading and firing mechanisms

   A small, cast-iron field cannon.
   Enlarge
   A small, cast-iron field cannon.

Muzzle-loaded Cannon

   The cannon is loaded with gunpowder and the cannonball through the
   muzzle, while a fuse is placed at the rear. This fuse is lighted,
   causing the gunpowder to ignite and propel the cannonball. Most cannons
   were land- or ship-based guns, although hand cannons also existed. In
   military use, the standard cannon was tremendously powerful, while hand
   cannon was somewhat useless. In the 19th century, the muzzle-loaded
   cannon was made obsolete by the breech-loaded artillery piece with a
   rifled barrel.

Muzzleloader

   Muzzle-loading muskets (smooth-bored long guns) were among the first
   small arms developed. The firearm was loaded through the muzzle with
   gunpowder, optionally some wadding and then a bullet (usually a solid
   lead ball, but musketeers could shoot stones when they ran out of
   bullets). Greatly improved muzzleloaders (usually rifled instead of
   smooth-bored) are manufactured today and have many enthusiast s, many
   of whom hunt large and small game with their guns. Muzzleloaders have
   to be manually reloaded after each shot; a skilled archer could fire
   multiple arrows faster than most early muskets could be reloaded and
   fired, although by the mid-18th century, when muzzleloaders became the
   standard small armament of the military, a well-drilled soldier could
   fire six rounds in a minute using prepared cartridges in his musket.
   Before then, effectiveness of muzzleloaders was hindered by both the
   low reloading speed and, before the firing mechanism was perfected, the
   very high risk posed by the firearm to the person attempting to fire
   it. One interesting solution to the reloading problem was the "Roman
   Candle Gun". This was a muzzleloader in which multiple charges and
   balls were loaded one on top of the other, with a small hole in each
   ball to allow the subsequent charge to be ignited after the one ahead
   of it was ignited. It was neither a very reliable nor popular firearm,
   but it enabled a form of "automatic" fire long before the advent of the
   machine gun.

   http://www.scotwars.com/html/equip_firearms2.htm#3

Matchlock

   Matchlocks were the first and simplest small arms firing mechanisms
   developed. Using the matchlock mechanism, the powder in the gun barrel
   was ignited by a piece of burning cord called a "match". The match was
   wedged into one end of an S-shaped piece of steel. As the trigger
   (often actually a lever) was pulled, the match was brought into the
   open end of a "touch hole" at the base of the gun barrel, which
   contained a very small quantity of gunpowder, igniting the main charge
   of gunpowder in the gun barrel. The match usually had to be relit after
   each firing.

Wheellock

   The wheellock action, a successor to the matchlock, predated the
   flintlock. Despite its many faults, the wheellock was a significant
   improvement over the matchlock in terms of both convenience and safety,
   since it eliminated the need to keep a smoldering match in proximity to
   loose gunpowder. It operated using a small wheel much like that on
   cigarette lighters which was wound up with a key before use and which,
   when the trigger was pulled, spun against a flint, creating the shower
   of sparks that ignited the powder in the touch hole. Supposedly
   invented by Leonardo da Vinci, the Italian Renaissance man, the wheel
   lock action was an innovation that was not widely adopted.

Flintlock

   The flintlock action was a major innovation in small arms design. The
   spark used to ignite the gunpowder in the touch hole was supplied by a
   sharpened piece of flint clamped in the jaws of a "cock" which, when
   released by the trigger, struck a piece of steel called the " frizzen"
   to create the necessary sparks. (The spring loaded arm that holds a
   piece of flint or pyrite is referred to as a cock because of its
   resemblance to a rooster.) The cock had to be manually reset after each
   firing, and the flint had to be replaced periodically due to wear from
   striking the frizzen. (See also flintlock mechanism, snaphance,
   miquelet) The flintlock was widely used during the 18th and 19th
   centuries in both muskets and rifles.

Percussion cap

   Percussion caps ( caplock mechanisms), coming into wide service in the
   19th century, were a dramatic improvement over flintlocks. With the
   percussion cap mechanism, the small primer charge of gunpowder used in
   all preceding small arms was replaced by a completely self-contained
   explosive charge contained in a small brass "cap". The cap was fastened
   to the touch hole of the gun (extended to form a "nipple") and ignited
   by the impact of the gun's "hammer". (The hammer is roughly the same as
   the cock found on flintlocks except that it doesn't clamp onto
   anything.) In the case of percussion caps the hammer was hollow on the
   end to fit around the cap in order to keep the cap from fragmenting and
   injuring the shooter. Once struck, the flame from the cap in turn
   ignited the main charge of gunpowder, as with the flintlock, but there
   was no longer any need to charge the touch hole with gunpowder, and
   even better, the touch hole was no longer exposed to the elements. As a
   result, the percussion cap mechanism was considerably safer, far more
   weatherproof, and vastly more reliable (cloth-bound cartridges
   containing a premeasured charge of gunpowder and a ball had been in
   regular military service for many years, but the exposed gunpowder in
   the entry to the touch hole had long been a source of misfires). All
   muzzleloaders manufactured since the second half of the 19th century
   use percussion caps except those built as replicas of the flintlock or
   earlier small arms.

Cartridges

   A major innovation in small arms (and light artillery) came in the
   second half of the 19th century when ammunition, previously delivered
   as separate bullets and powder, was combined in a single metallic
   (almost always brass) cartridge containing a percussion cap, powder,
   and a bullet in one weatherproof package. The main technical advantage
   of the brass cartridge case was the effective and reliable sealing of
   high pressure gasses at the breech, as the gas pressure forces the
   cartridge case to expand outward, pressing it firmly against the inside
   of the gun barrel chamber. This prevents the leakage of hot gas which
   could injure the shooter. The brass cartridge also opened the way for
   modern repeating arms, by uniting the bullet, gunpowder and primer into
   one assembly. Before this, a "cartridge" was simply a premeasured
   quantity of gunpowder together with a ball in a small cloth bag (or
   rolled paper cylinder), which also acted as wadding for the charge and
   ball. This early form of cartridge had to be rammed into the
   muzzleloader's barrel, and either a small charge of gunpowder in the
   touch hole or an external percussion cap mounted on the touch hole
   ignited the gunpowder in the cartridge. Cartridges with built-in
   percussion caps (called "primers") continue to this day to be the
   standard in firearms. In cartridge-firing firearms, a hammer (or a
   firing pin struck by the hammer) strikes the cartridge primer, which
   then ignites the gunpowder within. The primer charge is at the base of
   the cartridge, either within the rim (a "rimfire" cartridge) or in a
   small percussion cap embedded in the centre of the base (a "centerfire"
   cartridge). As a rule, centerfire cartridges are more powerful than
   rimfire cartridges, operating at considerably higher pressures than
   rimfire cartridges.

   Caseless cartridges are now being explored: instead of using brass as
   the cartridge case, these would hold the cartridge together with paper
   or some other substance that is destroyed when the gun is fired,
   eliminating the expense of brass casings which are ejected. Caseless
   cartridges and the guns that would use them are still prototypes,
   although the idea of caseless cartridges can be traced to the musket
   "cartridges" widely used by the 18th-century military.

   Nearly all contemporary firearms load cartridges directly into their
   breech. Some additionally or exclusively load from a magazine that
   holds multiple cartridges. A magazine is usually a box or cylinder that
   is designed to be reusable and is detachable from the gun. Some
   magazines, such as those of the Garand are internal to the firearm, and
   are loaded by using a clip, which is a device that looks like a rail
   holding the ammunition by the rim of the case. In most cases, a
   magazine and a clip are different in that the former's function is to
   feed ammunition into the firearm's breech, while the latter's is only
   to "charge" a magazine with fresh ammunition.

Repeating, semiautomatic, and automatic firearms

   Many small arms are "single shot" firearms: i.e., each time a cartridge
   is fired, the operator must manually re-cock the firearm and load
   another cartridge. The classic single-barreled shotgun is a good
   example. A firearm that can load multiple cartridges as the firearm is
   re-cocked is considered a "repeating firearm" or simply a "repeater".
   The lever-action rifle of Old West fame, a pheasant-hunter's pump
   shotgun, and a police sniper's bolt-action rifle are good examples of
   repeating firearms. A firearm that automatically re-cocks and reloads
   the next round with each trigger pull is considered a semiautomatic
   firearm. An automatic (or "fully automatic") firearm is one that
   automatically re-cocks, reloads, and fires as long as the trigger is
   depressed. Many modern military firearms have a "selective-fire"
   option, which is a mechanical switch that allows the firearm be fired
   either in the semiautomatic or fully automatic mode. In the current
   M16A2 and M16A4 variants of the U.S.-made M16, continuous
   full-automatic fire is not possible, having been replaced by an
   automatic burst of three cartridges that makes full-automatic fire
   considerably more accurate.

   The first "rapid firing" firearms were usually similar to the
   19th-century Gatling gun, which would fire cartridges from a magazine
   as fast as and as long as the operator turned a crank. Eventually, the
   "rapid" firing mechanism was perfected and miniaturized to the extent
   that either the recoil of the firearm or the gas pressure from firing
   could be used to operate it (which made the firing mechanisms truly
   "automatic"). Automatic rifles such as the Browning Automatic Rifle
   (the "BAR") were in common use by the military during the early part of
   the 20th century, and automatic rifles that fired handgun rounds, known
   as submachine guns, also appeared in this time.

   Submachine guns (such as the well-known Thompson gun) were originally
   about the size of carbines. Because they fire pistol ammunition, they
   have limited long-range use, but in close combat can spray bullets in a
   deadly and controllable manner due to the light recoil of the pistol
   ammunition. They are also extremely inexpensive and simple to build in
   time of war, enabling a nation to quickly arm its military. In the
   latter half of the 20th century, submachine guns were being
   miniaturized to the point of being only slightly larger than some large
   handguns. The most widely used submachine gun at the end of the 20th
   century was the Heckler & Koch MP5. The MP5 is actually designated as a
   "machine pistol" by Heckler & Koch (MP5 stands for Machine Pistol 5),
   although some reserve this designation for even smaller submachine guns
   such as the MAC-10, which are about the size and shape of pistols.

   Nazi Germany brought the world's attention to what eventually became
   the class of firearm most widely adopted by the military: the so-called
   assault rifle (see Sturmgewehr 44). An assault rifle is usually
   slightly smaller than a military rifle such as the M1 Garand, the M14
   or the K98k. Generally, assault rifles have mechanisms that allow the
   user to select between single shots, bursts of shots, or automatic
   fire. Moreover, assault rifles tend to incorporate military
   characteristics that make them look menacing: bayonet lugs, flash
   suppressors, and large capacity ammunition magazines. Generally, these
   design features are trivial in nature, and the modern military assault
   rifle differs very little in function from a civilian hunting rifle.
   Universally, civilian versions of military assault rifles are strictly
   semiautomatic. The cartridge fired by these rifles is midway in power
   between a pistol cartridge and a high-power rifle round, which gives
   the soldier the close-in spray ability of a submachine gun with the
   more precision long-range shooting of a high-power rifle round. Soviet
   engineer Mikhail Kalashnikov quickly adapted the concept to the AK-47,
   which has become the world's most widely used assault rifle. In United
   States, John Garand, the inventor of the M1 Garand rifle used by the
   U.S. military during World War II, adapted the assault rifle design to
   produce the M14, which was used by the U.S. military until the 1960s.
   The significant recoil (hence inaccuracy) of the M14 when fired in full
   automatic mode was seen as a problem, however, and in the 1960s it was
   replaced by Eugene Stoner's AR-15, which also marked a switch from the
   high-powered but heavy .30-caliber rifle used by the U.S. military
   since before World War I to the much smaller but far lighter and light
   recoiling (and arguably more accurate) .223-caliber rifle. The military
   later designated the AR-15 to the "M16". The civilian version of the
   M16 continues to be known as the AR-15 and looks exactly like the
   military version, although it lacks the mechanism that permits fully
   automatic fire.
   The French FAMAS, example of a bullpup riffle.
   Enlarge
   The French FAMAS, example of a bullpup riffle.

   Modern designs call for compact weapons retaining firepower. The
   bullpup design, by mounting the ammunition magazine rear of the trigger
   system, unifies the accuracy and firepower of the traditional assault
   riffle with the compact size of the submachine gun (though traditional
   submachine guns are still used because of the ballistic properties of
   the handgun ammunition that they use) ; examples are the French FAMAS
   or the British SA80.

   New ammunition design shapes the future of firearms. Recently, smaller
   but powerful ammunition have been introduced, as to allow personal
   defence weapons to defeat infantry armours. Such designs are the basis
   for the Five-seveN or the FN P90. Caseless ammunition are another
   trend, though empeded by the large number of traditional firearms,
   which would make their introduction expensive (an example is the German
   Heckler & Koch G11). The flechette is yet another improvement over
   traditional ammunition, allowing for extreme penetration abilities and
   a very flat trajectory.

   Retrieved from " http://en.wikipedia.org/wiki/Firearm"
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   with only minor checks and changes (see www.wikipedia.org for details
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