Repeating firearm

In a manually-operated repeating firearm (or "manual repeater" for short), the user needs to manually apply force to the action in order to operate it, either directly via a handle on the bolt, or indirectly via linkaged lever or slide.

Colt Holster Model Paterson Revolver No. 5

Circuit Judge revolver mechanism carbine

Revolvers use a rotating cylinder containing multiple chambers, which functions similarly to a rotary magazine (with each chamber holding a round of cartridge). When the hammer is cocked (either directly by hand, or indirect via trigger-pull), internal linkage will rotate the cylinder and index each chamber into alignment with the barrel bore. When fired, the bullet will make a slight "jump" across the gap between the cylinder and the barrel, creating out a small "breech blast" from any hot, high-pressure propellant gas that leaks out of the gap.

Although multiple-barrel "pepper-box" guns had appeared for centuries and were popular handguns in the early 19th century, the revolver was the first true repeating handgun. In 1836, Samuel Colt applied patent for a "revolving gun" later named the Colt Paterson; he was granted the patent on February 25, 1836 (later numbered 9430X).[13][14] This instrument and patent No. 1304, dated August 29, 1836, protected the basic principles of his revolving-breech-loading, folding-trigger firearm[15][16] and gave him a monopoly of revolver manufacture until 1857.[17] It was the first practical revolver and the first practical repeating firearm, and became an industrial and cultural legacy as well as a contribution to the development of war technology,[18] represented ironically by the name of one of his company's later innovations, the "Peacemaker".[19]

While some early long guns were also made using the revolver mechanism, these did not have longevity as it posed a problem with long guns: without special sealing details, the cylinder produces a gas discharge close to the face when the weapon is fired from the shoulder, as was a common approach with rifles.

Revolver cannon

Replica Puckle gun from Buckler's Hard Maritime Museum

Confederate revolving cannon

Modern Mauser BK-27 aircraft revolver cannon

A revolver cannon is a large-caliber gun (cannon) that uses a revolver-like cylinder to speed up the loading-firing-ejection cycle. Unlike a rotary cannon, a revolver cannon has only a single gun barrel. An early precursor was the Puckle gun of 1718, a large manually-operated flintlock gun, whose design idea was impractical due to it being far ahead of what 18th century technology could achieve. During the 19th century, The Confederate Army used a single 2-inch revolver cannon with 5 manually rotated chambers during the Siege of Petersburg.[20] The gun was captured in Danville, Virginia by the Union Army on April 27, 1865.[21]

Modern revolver cannons are actually automatically operated weapons. In 1905, C. M. Clarke patented[22] the first fully automatic, gas-operated rotary chamber gun, but his design was ignored at the time as it came as reciprocating-bolt automatic weapons like the Maxim gun and the Browning gun were peaking in popularity.[23] In 1932, the Soviet ShKAS machine gun, a 7.62 mm calibre aircraft ordnance, used a twelve-round capacity, revolver-style feeding mechanism with a single barrel and single chamber, to achieve firing rates of well over 1800 rounds per minute, and as high as 3,000 rounds per minute in special test versions in 1939, all operating from internal gas-operated reloading. Some 150,000 ShKAS weapons were produced for arming Soviet military aircraft through 1945.[24] Around 1935, Silin, Berezin and Morozenko worked on a 6000 rpm 7.62 mm aircraft machine gun using revolver design, called SIBEMAS (СИБЕМАС), but the project was abandoned.[25]

It was not until the mid-1940s that the first practical modern revolver cannon emerged.[26] The archetypal revolver cannon is the Mauser MK 213, from which almost all current revolver cannons are derived. In the immediate post-war era, Mauser engineers spread out from Germany and developed similar weapons around the world. Both the British and French made outright copies of the 30 mm versions of the MK 213, as the ADEN and DEFA, respectively. Switzerland produced the Oerlikon KCA. The American M39 cannon used the 20 mm version, re-chambered for a slightly longer 102 mm cartridge, intermediate between the 213's 82 mm and Hispano-Suiza HS.404's 110 mm. Several generations of the basic ADEN/DEFA weapons followed, remaining largely unchanged into the 1970s.[27] Around that time, a new generation of weapons developed, based on the proposed NATO 25 mm caliber standard and the Mauser 27 mm round. A leading example is the Mauser BK-27. In the 1980s, the French developed the GIAT 30, a newer generation power-driven revolver cannon. The Rheinmetall RMK30 modifies the GIAT system further, by venting the gas to the rear to eliminate recoil. Larger experimental weapons have also been developed for anti-aircraft use, like the Anglo-Swiss twin barrel but single chamber 42 mm Oerlikon RK 421 given the code name "Red King" and the related single-barrel "Red Queen" - all of which were cancelled during development.[28] The largest to see service is the Rheinmetall Millennium 35 mm Naval Gun System.

Soviet revolver cannon are less common than Western ones, especially on aircraft. A mechanism for a Soviet revolver-based machine gun was patented in 1944.[29] The virtually unknown Rikhter R-23 was fitted only to some Tu-22 models, but later abandoned in favor of the two-barrel, Gast gun Gryazev-Shipunov GSh-23 in the Tu-22M. The Rikhter R-23 does have the distinction of being fired from the space station Salyut 3. The Soviet navy has also adopted a revolver design, the NN-30, typically in a dual mount in the AK-230 turret.

Marlin Model 1894C lever-action carbine in .357 Magnum caliber

A Volcanic lever-action pistol

In a classic Henry-Winchester type lever-action firearm, cartridges are loaded tandemly into a tubular magazine below the barrel. A short bolt is manipulated via linkage to a pivoted cocking lever. Once closed, an over-center toggle action helps locking the bolt in place and prevents the breech from opening accidentally when the weapon is fired. The cocking lever is often integral with the trigger guard, and gets manually flexed down and forward when operated. An interlock prevents firing unless the toggle is fully closed. The famous Model 1873 Winchester is exemplary of this type. Later lever-action designs, such as Marlin lever guns and those designed for Winchester by John Browning, use one or two vertical locking blocks instead of a toggle-link. There also exist lever-action rifle/shotguns that feed from a box magazine, which allows them to use pointed bullets. Some of the early manual repeating pistols (e.g. Volcanic pistol) also use a scaled-down version of lever-action.

A one-off example of lever-action loading on an automatic firearm is the M1895 Colt–Browning machine gun. This weapon had a swinging lever beneath its barrel that was actuated by a gas bleed in the barrel, unlocking the breech to reload. This unique operation gave the nickname "potato digger" as the lever swung each time the weapon fired.

The Colt Lightning .22 pump action rifle

With a pump-action firearm, the action is operated by sliding a movable handguard on the fore-end backwards and forwards, with manipulated the bolt via linkage to eject a spent round, and extract and chamber a fresh round of ammunition. Pump-actions are usually associated with shotguns, but one example of a pump-action rifle is the Remington Model 7600 series. Rifles with pump action are also called slide-action. This style of rifle is still popular with some local law enforcement branches as a rifle that is easy to train officers who are already familiar with the pump shotgun.

Opened bolt on a Winchester Model 70, with an engine turned finish

Blaser R8 Professional straight-pull rifle

In bolt-action firearms, the bolt is operated by directly gripping a bolt handle (usually on the right side) to extract spent cartridges case, push new rounds into the chamber and reset the hammer/striker to ready the weapon for firing again.

Most bolt-action firearms use a rotating-bolt ("turn-and-pull") design. When the bolt is closed against the breech end of the gun barrel, it is locked onto the receiver via protruded lugs (usually on the bolt head) and occasionally also aided by the bolt handle that fits into a notch. To unlock the bolt, the handle must be rotated upwards first, which will shift the locking lugs out of their corresponding sockets. This allows the bolt to then be physically pulled rearwards, opening the barrel breech. An extractor on the bolt will hook onto the rim and pull out any cartridge (either fired or unused) remaining in the chamber, allowing it to be ejected from the gun. When the bolt is fully pulled to the rearmost position, the hammer/striker will get loaded against a spring and trapped by the sear, a process known as cocking. At the same time, the magazine will lift another round of its stored cartridges up into the path of the bolt head, so moving the bolt forwards will push this new round into the chamber. The bolt handle is then rotated downward for relocking, the gun is safe and ready for another firing. The Mauser Gewehr 98 rifle is the most famous and influential bolt-action design, with many similar weapons derived from its pioneering design concept, such as the Karabiner 98 Kurz (abbreviated often as Kar98k or simply K98), the M1903 Springfield and the Arisaka Type 38 rifles. The Russian Mosin–Nagant rifle, the British Lee–Enfield, and the Norwegian Krag–Jørgensen are examples of alternate bolt-action designs.

Another much rarer type of bolt-action is the straight-pull system, which uses complex bolt head mechanisms to facilitate locking. Straight-pull designs do not require the bolt handle to be rotated, allowing the user to cycle the action linearly, reducing the movements needed from four to only two and thus significantly increasing the rate of fire. Examples of such firearms include the Schmidt–Rubin, Mannlicher M1886/M1888/M1890/M1895, M1895 Lee Navy, Ross rifle, Anschütz 1827 Fortner, Blaser R93/R8 and VKS.

Self-loading (or autoloading) repeating firearms can utilize some of the excess energy released from propellant combustion to cycle its action and facilitate loading of subsequent rounds of ammunition into the chamber. Depending on whether the action can automatically perform both the loading and ignition procedures, or only automatically load the ammo but require manual actuation of the hammer/striker, self-loading repeaters can be categorized into fully automatic and semi-automatic firearms.

Ruger Standard (Mark I)

In blowback operation, the bolt is not actually locked at the moment of firing. To prevent violent recoil, in most firearms using this mechanism the opening of the bolt is delayed in some way. In many small arms, the round is fired while the bolt is still travelling forward, and the bolt does not open until this forward momentum is overcome. Other methods involve delaying the opening until two rollers have been forced back into recesses in the receiver in which the bolt is carried. Simple blowback action is simple and inexpensive to manufacture, but is limited in the power it can handle, so it is seen on small caliber weapons such as machine pistols and submachine guns. Lever-delayed blowback, as seen in for example the French FAMAS assault rifle, can also handle more powerful cartridges but is more complicated and expensive to manufacture.

The Mannlicher M1894

Blow-forward firearms uses incorporates a frame with a fixed breech face and the barrel moves away from the breech (frame) during the cycle of operation, in contrast to blowback firearms, which have the frame fixed to the barrel and the breech face moves in relation to the frame. The breech face is a part of the moving slide or bolt, depending on the layout of the blowback firearm. During firing, the friction of the bullet traveling down the barrel and the bore pressure pulls the barrel forward.[30] This mechanism contains a minimum of moving parts (the barrel and spring are generally the only moving parts) and is more compact than other operating mechanism of equal barrel length. However, due to the reduced mass of rear-moving parts coupled with the increased mass of the forward-moving parts (the barrel plus the bullet and propellant gasses), recoil energy is significantly greater than other operating mechanisms. Most blow-forward guns rely partially on the inertia of the barrel as the rest of the firearm recoil away from it.[31][32]

The first blow-forward firearm was the Mannlicher M1894 pistol and protected under U.S. Patent 581,296. The principle has been used in a few other weapons, including Schwarzlose Model 1908, Hino Komuro M1908, HIW VSK, Mk 20 Mod 0 grenade launcher, Pancor Jackhammer and Howa Type 96.

M1941 Johnson rifle

In a recoil-operated firearm, the breech is locked, and the barrel recoils as part of the firing cycle. In long-recoil actions, such as the Browning Auto-5 shotgun, the barrel and breechblock remain locked for the full recoil travel, and separate on the return; in short-recoil actions, typical of most semiautomatic handguns (e.g. the Colt M1911), the barrel recoils only a short distance before decoupling from the breechblock.

FN FAL battle rifle

In a gas-operated mechanism, a portion of the gases propelling the bullet from the barrel are extracted and used to operate a piston. The motion of this piston in turn unlocks and operates the bolt, which performs extraction of the spent cartridge and via spring action readies the next round. Almost all modern military rifles use mechanisms of this type.

6-barreled Phalanx CIWS aboard USS Jason Dunham

Rotary-barrel firearms (or rotary guns for short) uses multiple paraxial barrels in a rotating assembly, with each barrel firing automatically when rotated to a designated position, to achieve a rate of fire proportional to the speed of the barrel rotation. Rotary guns are typically belt-fed, though the earlier versions used top-mounted box magazines. Each barrel is paired with a cam-driven reciprocating action, so every barrel-action group is technically an independent repeater unit whose operating status corresponds to its rotational position within the assembly, and at any moment all the groups are at different stages of operating cycle to each other. Due to their capability to tolerate extremely rapid-firing (much higher than single-barreled automatic weapons of the same caliber), rotary guns are frequently used to deliver direct saturation fire for suppression and area denial. Early rotary guns are manually powered, and though quite successful at the time, was largely replaced from the battlefield before the turn of the 20th century by newer and more reliable machine guns such as the Maxim gun, but made a comeback during the Cold War in the form of automatic rotary cannons.

One of the main reasons for the resurgence of these electrically/hydraulically powered multiple-barrel guns is the system's inherent tolerance for continuous high rates of fire. For example, 1000 rounds per minute of continuous fire from a conventional single-barrel weapon ordinarily results in rapid barrel overheating followed by action stoppages caused also by overheating; in contrast, a five-barreled rotary gun firing 1000 rounds per minute endures only 200 rounds per minute for each barrel. The other factor is that while single-barrel designs can achieve high cycling rates, each loading-extraction cycle can only commence after the previous cycle is physically complete, or else the system will jam mechanically, and the risk of such malfunction increases exponentially with increasingly higher cycling rates; a multiple-barrel design however allows multiple barrel-action groups to work simultaneously in overlapped, differentially timed cycles, thus diffusing the operational stress of each action into the duration of an entire barrel rotation (which is multitudes more than the cycle time of a single-barrel automatic firearm with the same firing rate). The design also solves the problem of defective ammunition, which can cause a typical single-barrel machine gun to cease operation when a cartridge fails to load, fire or eject; as a rotary gun is normally powered by an external power source, the barrel rotation will continue independently, ejecting any defective rounds indifferently as part of the operational cycle, and the firing will merely experience a brief pause for that non-firing barrel before resuming to usual firing with other barrels.

A 1876 Gatling gun kept at Fort Laramie National Historic Site

An unmounted M61A1 Vulcan with flash suppressor used in the SUU-16/A gun pod

GAU-17/A fired from a UH-1N

Four Soviet/Russian rotary cannons arranged in ascending caliber, from the left: GShG-7.62, GSh-6-23, GSh-6-30, AK-630

The seven-barrelled 30 mm GAU-8 Avenger rotary cannon of an A-10 Thunderbolt II

The earliest rotary-barrel firearm is the Gatling gun, invented by Richard Jordan Gatling in 1861, and patented on November 4, 1862.[33][34] The Gatling gun operated by a hand-crank mechanism, with six barrels revolving around a central shaft (although some models had as many as ten). Each barrel fires once per revolution at about the same 4 o'clock position. The barrels, a carrier and a lock cylinder were separate and all mounted on a solid plate, mounted on an oblong fixed frame. Manually turning the crank rotated the shaft. The carrier was grooved and the lock cylinder was drilled with holes corresponding to the barrels. Cartridges, held in a hopper-like magazine on top, dropped individually into the grooves of the carrier. The lock was simultaneously forced by the cam to move forward and load the cartridge, and when the cam was at its highest point, the cocking ring freed the lock and fired the cartridge. After the cartridge was fired the continuing action of the cam drew back the lock bringing with it the spent casing which then dropped to the ground.

The Gatling gun was first used in combat during the American Civil War. Twelve of the guns were purchased personally by Union Army commanders and used in the trenches during the Siege of Petersburg (June 1864—April 1865).[35] Eight other Gatling guns were fitted on gunboats.[36] The gun was not accepted by the Army until 1866, when a sales representative of the manufacturing company demonstrated it in combat.[37] On July 17, 1863, Gatling guns were purportedly used to overawe New York anti-draft rioters.[38] Post-Civil War, two Gatling guns were brought by a Pennsylvania National Guard unit from Philadelphia to use against strikers in the Pittsburgh Railway Riots. During the American Indian Wars, Gatling guns saw frequent service, though famously not used at the Battle of the Little Bighorn when Gen. George Armstrong Custer chose not to bring any with his main force. In 1885, Lieutenant Arthur L. Howard of the Connecticut National Guard took a personally owned Gatling gun to Saskatchewan, Canada for use with the Canadian military against Métis rebels during Louis Riel's North-West Rebellion.[37]

Gatling guns were used by the U.S. Army during both the Spanish–American War and the Philippine–American War.[39] A four-gun battery of Colt-made Model 1895 ten-barrel Gatling guns in .30 Army was formed into a separate detachment led by Lt. John "Gatling Gun" Parker.[40] The detachment proved very effective, supporting the advance of American forces at the Battle of San Juan Hill. Three of the Gatlings with swivel mountings were used with great success against the Spanish defenders.[41] Despite this, the Gatling's weight and cumbersome artillery carriage hindered its ability to keep up with infantry forces over difficult ground, particularly in Cuba and the Philippines, where outside the major cities there were heavily foliaged forests and steep mountain paths, and the roads were often little more than jungle footpaths.

Elsewhere, a Gatling gun was purchased in April 1867 for the Argentine Army by minister Domingo F. Sarmiento under instructions from president Bartolomé Mitre.[42] Captain Luis Germán Astete of the Peruvian Navy took dozens of Gatling guns with him in December 1879 from the United States for use during the Peru-Chile War of the Pacific, especially in the Battle of Tacna (May 1880) and the Battle of San Juan (January 1881). The Gatling gun was used most successfully to expand European colonial empires in Africa to defeat mounting massed attacks by indigenous warriors (e.g. the Zulu, Bedouin, and Mahdists).[37] Imperial Russia purchased 400 Gatling guns against Turkmen cavalry and other nomads of Central Asia.[43] The British Army first deployed the Gatling gun in 1873-74 during the Anglo-Ashanti wars, and extensively during the latter actions of the 1879 Anglo-Zulu war.[44] The Royal Navy used Gatling guns during the 1882 Anglo-Egyptian War.[45]

After the original Gatling gun was replaced in service by newer recoil-/gas-operated machine guns, the approach of using multiple rotating barrels fell into disuse for many decades. However, some prototypes were developed during the interwar years, but rarely used. During World War I, Imperial Germany worked on the Fokker-Leimberger, an externally powered 12-barrel Gatling gun nicknamed "nutcracker", that could fire more than 7,200 rounds per minute,[46] though many accused it of exaggeration.[47][48] Failures during the war were attributed to the poor quality of German wartime ammunition,[48] although the type of breech employed had ruptured-case problems in a British 1950s experimental weapon.[47] Fokker continued to experiment with this type of breech after his post-war move to the United States. A different Fokker prototype in a US museum attests to the failure of this line of development.[49]

After World War II, the U.S. Army Air Force determined that an improved automatic cannon ith an extremely high rate of fire was required agaisnt fast-moving enemy jet aircraft. Using experience gained from the Luftwaffe MG 151 and MK 108 cannons, a larger-caliber cannon shell for the new gun was deemed desirable. In June 1946, the General Electric Company was awarded a U.S. military defense contract to develop a high-ROF aircraft gun, which GE termed "Project Vulcan". While researching prior work, ordnance engineers recalled the experimental electrically-driven Gatling weapons from the turn of the 20th century. In 1946, a Model 1903 Gatling gun borrowed from a museum was set up with an electric motor and test-fired, briefly managing a rate of 5,000 rounds per minute. In 1949, GE began testing the first model of its modified Gatling design, now called the Vulcan Gun. The first prototype was designated the T45 (Model A), firing .60 in (15 mm) ammunition at about 2,500 rounds per minute from six barrels, and in 1950 GE delivered ten initial Model A .60 cal. T45 guns for evaluation. Thirty-three model C T45 guns in three calibers (.60 cal., 20 mm and 27 mm) were delivered in 1952 for additional testing. After extensive testing, the T171 20mm gun was selected for further development, and was standardized by the U.S. Army and U.S. Air Force in 1956 as the M61 Vulcan gun.