A breechloader   is a firearm in which the user loads the ammunition (cartridge or shell) via the rear (breech) end of its barrel, as opposed to a muzzleloader, which loads ammunition via the front (muzzle).
Modern firearms are generally breech-loading, while early firearms before the mid-19th century were almost entirely muzzle-loading. Mortars and the Russian GP-25 grenade launcher are the only muzzleloaders remaining in frequent modern usage. However, referring to a weapon specifically as breech loading is mostly limited to single-shot or otherwise non-repeating firearms, such as double-barreled shotguns and double rifles.
Breech-loading provides the advantage of reduced reloading time, because it is far quicker to load the projectile and propellant into the chamber of a gun/cannon than to reach all the way over to the front end to load ammunition and then push them back down a long tube – especially when the projectile fits tightly and the tube has spiral ridges from rifling. In field artillery, the advantages were similar – crews no longer had to get in front of the gun and pack ammunition in the barrel with a ramrod, and the shot could now tightly fit the bore, increasing accuracy. It also made it easier to load a previously fired weapon with a fouled barrel. Gun turrets and emplacements for breechloaders can be smaller, since crews don't need to retract the gun for frontal loading. Unloading a breechloader is much easier as well, as the load can be extracted from the breech end and is often doable by hand; unloading muzzle loaders requires drilling into the projectile to drag it out through whole length of the barrel, and in some cases they are simply fired to unload.
After breech-loading became common, it also became common practice to fit recoil systems onto field guns to prevent the recoil from rolling the carriage back with every shot and ruining the aim. That provided faster firing times, but is not directly related to whether the gun is breech-loading or not. Now that guns were able to fire without the entire carriage recoiling, the crew was able to remain grouped closely around the gun, ready to load and put final touches on the aim, prior to firing the next shot. That led to the development of an armored shield fitted to the carriage of the gun, to help shield the crew from long range area or sniper fire from the new, high-velocity, long-range rifles, or even machine guns.
Although breech-loading firearms were developed as far back as the early 14th century in Burgundy and various other parts of Europe,   breech-loading became more successful with improvements in precision engineering and machining in the 19th century.
The main challenge for developers of breech-loading firearms was sealing the breech. This was eventually solved for smaller firearms by the development of the self-contained metallic cartridge. For firearms too large to use cartridges, the problem was solved by the development of the interrupted screw.
Breech-loading swivel guns were invented in the 14th century. They were a particular type of swivel gun, and consisted in a small breech-loading cannon equipped with a swivel for easy rotation, loaded by inserting a mug-shaped chamber already filled with powder and projectiles. The breech-loading swivel gun had a high rate of fire, and was especially effective in anti-personnel roles.
Breech-loading firearms are known from the 16th century. Henry VIII possessed one, which he apparently used as a hunting gun to shoot birds.  Meanwhile, in China, an early form of breech-loading musket, known as the Che Dian Chong, was known to have been created in the second half of the 16th century for the Ming dynasty's arsenals.  Like all early breech-loading fireams, gas leakage was a limitation and danger present in the weapon's mechanism. 
More breech-loading firearms were made in the early 18th century. One such gun known to have belonged to Philip V of Spain, and was manufactured circa 1715, probably in Madrid. It came with a ready-to load reusable cartridge. 
Patrick Ferguson, a British Army officer, developed in 1772 the Ferguson rifle, a breech-loading flintlock firearm. Roughly two hundred of the rifles were manufactured and used in the Battle of Brandywine, during the American Revolutionary War, but shortly after they were retired and replaced with the standard Brown Bess musket. In turn the American army, after getting some experience with muzzle-loaded rifles in the late 18th century, adopted the second standard breech-loading firearm in the world, M1819 Hall rifle, and in larger numbers than the Ferguson rifle.
About the same time and later on into the mid-19th century, there were attempts in Europe at an effective breech-loader. There were concentrated attempts at improved cartridges and methods of ignition.
In Paris in 1808, in association with French gunsmith François Prélat, Jean Samuel Pauly created the first fully self-contained cartridges:  the cartridges incorporated a copper base with integrated mercury fulminate primer powder (the major innovation of Pauly), a round bullet and either brass or paper casing.   The cartridge was loaded through the breech and fired with a needle. The needle-activated central-fire breech-loading gun would become a major feature of firearms thereafter.  The corresponding firearm was also developed by Pauly.  Pauly made an improved version, which was protected by a patent on 29 September 1812. 
The Pauly cartridge was further improved by the French gunsmith Casimir Lefaucheux in 1828, by adding a pinfire primer, but Lefaucheux did not register his patent until 1835: a pinfire cartridge containing powder in a card-board shell.
In 1845, another Frenchman Louis-Nicolas Flobert invented, for indoor shooting, the first rimfire metallic cartridge, constituted by a bullet fit in a percussion cap.   Usually derived in the 6 mm and 9 mm calibres, it is since then called the Flobert cartridge but it does not contain any powder; the only propellant substance contained in the cartridge is the percussion cap itself.  In English-speaking countries the Flobert cartridge corresponds to the .22 BB and .22 CB ammunitions.
In 1846, yet another Frenchman, Benjamin Houllier, patented the first fully metallic cartridge containing powder in a metallic shell.  Houllier commercialised his weapons in association with the gunsmiths Blanchard or Charles Robert.   But the subsequent Houllier and Lefaucheux cartridges, even if they were the first full-metal shells, were still pinfire cartridges, like those used in the LeMat (1856) and Lefaucheux (1858) revolvers, although the LeMat also evolved in a revolver using rimfire cartridges.
The first centrefire cartridge was introduced in 1855 by Pottet, with both Berdan and Boxer priming. 
In 1842, the Norwegian Armed Forces adopted the breech-loading caplock, the Kammerlader, one of the first instances in which a modern army widely adopted a breech-loading rifle as its main infantry firearm.
The Dreyse Zündnadelgewehr (Dreyse needle gun) was a single-shot breech-loading rifle using a rotating bolt to seal the breech. It was so called because of its .5-inch needle-like firing pin, which passed through a paper cartridge case to impact a percussion cap at the bullet base. It began development in the 1830s under Johann Nicolaus von Dreyse and eventually an improved version of it was adopted by Prussia in the late 1840s. The paper cartridge and the gun had numerous deficiencies; specifically, serious problems with gas leaking. However, the rifle was used to great success in the Prussian army in the Austro-Prussian war of 1866. This, and the Franco-Prussian war of 1870–71, eventually caused much interest in Europe for breech-loaders and the Prussian military system in general.
In 1860, the New Zealand government petitioned the Colonial Office for more soldiers to defend Auckland.  The bid was unsuccessful and the government began instead making inquiries to Britain to obtain modern weapons. In 1861 they placed orders for the Calisher and Terry carbine, which used a breech-loading system using a bullet consisting of a standard Minié lead bullet in .54 calibre backed by a charge and tallowed wad, wrapped in nitrated paper to keep it waterproof. The carbine had been issued in small numbers to English cavalry (Hussars) from 1857. About 3–4,000 carbines were brought into New Zealand a few years later. The carbine was used extensively by the Forest Rangers, an irregular force led by Gustavus von Tempsky that specialized in bush warfare and reconnaissance. Von Tempsky liked the short carbine, which could be loaded while lying down. The waterproofed cartridge was easier to keep dry in the New Zealand bush. Museums in New Zealand hold a small number of these carbines in good condition.  
During the American Civil War, at least nineteen types of breech-loaders were fielded.  The Sharps used a successful dropping block design. The Greene used rotating bolt-action, and was fed from the breech. The Spencer, which used lever-actuated bolt-action, was fed from a seven-round detachable tube magazine. The Henry and Volcanic used rimfire metallic cartridges fed from a tube magazine under the barrel. These held a significant advantage over muzzle-loaders. The improvements in breech-loaders had spelled the end of muzzle-loaders. To make use of the enormous number of war surplus muzzle-loaders, the Allin conversion Springfield was adopted in 1866. General Burnside invented a breech-loading rifle before the war, the Burnside carbine.
The French adopted the new Chassepot rifle in 1866, which was much improved over the Dreyse needle gun as it had dramatically fewer gas leaks due to its de Bange sealing system. The British initially took the existing Enfield and fitted it with a Snider breech action (solid block, hinged parallel to the barrel) firing the Boxer cartridge. Following a competitive examination of 104 guns in 1866, the British decided to adopt the Peabody-derived Martini-Henry with trap-door loading in 1871.
Single-shot breech-loaders would be used throughout the latter half of the 19th century, but were slowly replaced by various designs for repeating rifles, first used in the American Civil War. Manual breech-loaders gave way to manual magazine feed and then to self-loading rifles.
Breech-loading is still commonly used in shotguns and hunting rifles.
The first modern breech-loading rifled gun is a breech-loader invented by Martin von Wahrendorff with a cylindrical breech plug secured by a horizontal wedge in 1837. In the 1850s and 1860s, Whitworth and Armstrong invented improved breech-loading artillery.
The M1867 naval guns produced in Imperial Russia  at the Obukhov State Plant used Krupp technology.
A breech action is the loading sequence of a breech loading naval gun or small arm. The earliest breech actions were either three-shot break-open actions or a barrel tip-down, remove the plug and reload actions. The later breech-loaders included the Ferguson rifle, which used a screw-in/screw out action to reload, and the Hall rifle, which tipped up at 30 degrees for loading. The better breech loaders, however, used percussion caps, including the Sharps rifle, using a falling block (or sliding block) action to reload. And then later on came the Dreyse needle gun that used a moving seal (bolt) to seal and expose the breech. Later on, however, the Mauser M71/84 rifle used self-contained metallic cartridges and used a rotating bolt to open and close the breech.
A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries.
A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves (rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with both hands and braced firmly against the shooter's shoulder via a buttstock for stability during shooting. Rifles are used extensively in warfare, law enforcement, hunting, shooting sports, and crime.
In firearm designs, the term single-shot refers to guns that can hold only a single round of ammunition inside and thus must be reloaded manually after every shot. Compared to multi-shot repeating firearms ("repeaters"), single-shot designs have no moving parts other than the trigger, hammer/firing pin or frizzen, and therefore do not need a sizable receiver behind the barrel to accommodate a moving action, making them far less complex and more robust than revolvers or magazine/belt-fed firearms, but also with much slower rates of fire.
The percussion cap or percussion primer, introduced in the early 1820s, is a type of single-use percussion ignition device for muzzle loader firearm locks enabling them to fire reliably in any weather condition. This crucial invention gave rise to the cap lock mechanism or percussion lock system using percussion caps struck by the hammer to set off the gunpowder charge in percussion guns including percussion rifles and cap and ball firearms. Any firearm using a caplock mechanism is a percussion gun. Any long gun with a cap-lock mechanism and rifled barrel is a percussion rifle. Cap and ball describes cap-lock firearms discharging a single bore-diameter spherical bullet with each shot.
A cartridge or a round is a type of pre-assembled firearm ammunition packaging a projectile, a propellant substance and an ignition device (primer) within a metallic, paper, or plastic case that is precisely made to fit within the barrel chamber of a breechloading gun, for the practical purpose of convenient transportation and handling during shooting. Although in popular usage the term "bullet" is often informally used to refer to a complete cartridge, it is correctly used only to refer to the projectile.
Bolt-action is a type of manual firearm action that is operated by directly manipulating the bolt via a bolt handle, which is most commonly placed on the right-hand side of the firearm.
In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles the ammunition cartridges, or the method by which that mechanism works. Actions are technically not present on muzzleloaders, as all those are single-shot firearms with a closed off breech with the powder and projectile manually loaded from the muzzle. Instead, the muzzleloader ignition mechanism is referred to as the lock.
The Chassepot, officially known as Fusil modèle 1866, was a bolt-action military breechloading rifle. It is famous for having been the arm of the French forces in the Franco-Prussian War of 1870–1871. It replaced an assortment of Minié muzzleloading rifles, many of which were converted in 1864 to breech loading. An improvement to existing military rifles in 1866, the Chassepot marked the commencement of the era of modern bolt action, breech-loading military rifles. The Gras rifle was an adaption of the Chassepot designed to fire metallic cartridges introduced in 1874.
Rimfire ammunition is a type of firearm metallic cartridge whose primer is located within a hollow circumferential rim protruding from the base of its casing. When fired, the gun's firing pin will strike and crush the rim against the edge of the barrel breech, sparking the primer compound within the rim, and in turn ignite the propellant within the case. Invented in 1845, by Louis-Nicolas Flobert, the first rimfire metallic cartridge was the .22 BB Cap cartridge, which consisted of a percussion cap with a bullet attached to the top. While many other different cartridge priming methods have been tried since the 19th century, only rimfire and the later centerfire cartridges survive to the present day with regular usages. The .22 Long Rifle rimfire cartridge, introduced in 1887, is by far the most common ammunition in the world today in terms of units sold.
A firing pin or striker is a part of the firing mechanism of a firearm that impacts the primer in the base of a cartridge and causes it to fire. In firearms terminology, a striker is a particular type of firing pin where a compressed spring acts directly on the firing pin to provide the impact force rather than it being struck by a hammer.
A pinfire cartridge is an obsolete type of metallic firearm cartridge in which the priming compound is ignited by striking a small pin which protrudes radially from just above the base of the cartridge. Invented by Frenchman Casimir Lefaucheux in the 1830s but not patented until 1835, it was one of the earliest practical designs of a metallic cartridge. Its history is closely associated with the development of the breechloader which replaced muzzle-loading weapons.
The Remington M1867 was a rolling-block rifle, the first rifle using metallic cartridges to be adopted by the Norwegian and Swedish armies. Nominally it had a caliber of 4 decimal lines, but the actual caliber was 3.88 Norwegian decimal lines or 4.1 Swedish decimal lines (12.17 mm), and it fired a rimfire round with a 12.615 mm lead bullet. The 12.17 mm caliber was chosen because the Swedish army had approximately 30,000 new muzzle-loading M1860 and breech-loading M1864 rifles in 12.17 mm caliber in stock, rifles that were suitable for conversion to M1867 rolling-block rifles. With the exception of the first 10,000 rifles and 20,000 actions, which were made by Remington in the US, all Remington M1867 rifles and carbines were made under license in Norway and Sweden, by Kongsberg Vaapenfabrik in Norway, and by Husqvarna Vapenfabriks Aktiebolag and Carl Gustafs stads Gevärsfaktori in Sweden with the two Swedish manufacturers producing about 80% of the weapons.
The Dreyse needle-gun was a ground-breaking 19th-century military breechloading rifle. The gun, which was the first breech-loading rifle to use a bolt action to open and close the chamber, was the main infantry weapon of the Prussians in the Wars of German Unification. It was invented in 1836 by the German gunsmith Johann Nikolaus von Dreyse (1787–1867) who had been conducting numerous design experiments since 1824.
Johann Nicolaus von Dreyse was a German firearms inventor and manufacturer. He is most famous for submitting the Dreyse needle gun in 1836 to the Prussian army, which was adopted for service in December 1840 as the Leichte Perkussions-Gewehr M 1841 – a name deliberately chosen to mislead about the rifle's mechanism – later renamed Zündnadelgewehr M 1841 in 1855.
The M1819 Hall rifle was a single-shot breech-loading rifle designed by John Hancock Hall, patented on May 21, 1811, and adopted by the U.S. Army in 1819. It was preceded by the Harpers Ferry M1803. It used a pivoting chamber breech design and was made with either flintlock or percussion cap ignition systems. The years of production were from the 1820s to the 1840s at the Harpers Ferry Arsenal. This was the first breech-loading rifle to be adopted in large numbers by any nation's army, but not the first breech-loading military rifle – the Ferguson rifle was used briefly by the British Army in the American Revolutionary War. The Hall rifle remained overshadowed by common muskets and muzzleloading rifles which were still prevalent until the Civil War. The early flintlocks were mostly converted to percussion ignition.
The following are terms related to firearms and ammunition topics.
A paper cartridge is one of various types of small arms ammunition used before the advent of the metallic cartridge. These cartridges consisted of a paper cylinder or cone containing the bullet, gunpowder, and in some cases, a primer or a lubricating and anti-fouling agent. Combustible cartridges are paper cartridges that use paper treated with oxidizers to allow them to burn completely upon ignition.
Casimir Lefaucheux was a French gunsmith. He was born in Bonnétable and died in Paris.
The .44 Henry, also known as the .44 Rimfire, the .44 Long Rimfire, or the 11x23mmR in Europe, is a rimfire rifle and handgun cartridge featuring a .875 in (22.2 mm)-long brass or copper case. The round has a total overall length of 1.345 in (34.2 mm), with a 200 or 216 gr .446 in (11.3 mm)-diameter cast solid-lead heeled bullet. The original propellant load is 26 to 28 gr of black powder. The round has a muzzle velocity of approximately 1,125 ft/s (343 m/s), giving a muzzle energy of 568 foot-pounds.
A needle gun is a firearm that has a needle-like firing pin, which can pass through the paper cartridge case to strike a percussion cap at the bullet base.