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Recoil operation is an operating mechanism used to implement locked-breech autoloading firearms. Recoil operated firearms use the energy of recoil to cycle the action, as opposed to gas operation or blowback operation using the pressure of the propellant gas. [1]
The earliest mention of recoil used to assist the loading of firearms is sometimes claimed to be in 1663 when an Englishman called Palmer proposed to employ either it or gases tapped along a barrel to do so. [2] However no one has been able to verify this claim in recent times, although there is another automatic gun that dates from the same year, but its type and method of operation are unknown. [3] Recoil-operation, if it was invented in 1663, would then lie dormant until the 19th century, when a number of inventors started to patent designs featuring recoil operation; this was due to the fact that the integrated disposable cartridge (both bullet and propellant in one easily interchangeable unit) made these designs viable. The earliest mention of recoil operation in the British patent literature is a patent by Joseph Whitworth filed in 1855 which proposed to use recoil to partially open the breech of a rifle, the breech then being manually pulled the rest of the way back by hand. [4] Around this time, an American by the name of Regulus Pilon is sometimes stated to have patented in Britain a gun that used a limited form of recoil operation. He had three British patents related to firearms around the 1850s to the 1860s; however, all of them refer to a means of dampening recoil in firearms, which wasn't a new idea at the time, rather than true recoil operation. The next to mention recoil operation in the British patent literature is by Alexander Blakely in 1862, who clearly describes using the recoil of a fired cannon to open the breech. [5] In 1864 after the Second Schleswig War, Denmark started a program intended to develop a gun that used the recoil of a fired shot to reload the firearm, though a working model wouldn't be produced until 1888. [6] Later in the 1870s, a Swedish captain called D. H. Friberg patented a design which introduced both flapper-locking and the fully automatic recoil operated machine gun. [7] Furthermore, in 1875 a means of cocking a rifle through recoil was patented through the patent agent Frank Wirth by a German called Otto Emmerich. [8] Finally came Maxim's 1883 automatic recoil operated machine gun which introduced the modern age of automatic machine guns.
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 ANIMATION Browning AUTO 5 "cycle of one shoot", YouTube |
The same forces that cause the ejecta of a firearm (the projectile(s), propellant gas, wad, sabot, etc.) to move down the barrel also cause all or a portion of the firearm to move in the opposite direction. The result is required by the conservation of momentum such that the ejecta momentum and recoiling momentum are equal. These momenta are calculated by:
The barrel is a moving part of the action in recoil-operated firearms. In non-recoil-operated firearms, it is generally the entire firearm that recoils. However, in recoil-operated firearms, only a portion of the firearm recoils while inertia holds another portion motionless relative to a mass such as the ground, a ship's gun mount, or a human holding the firearm. The moving and the motionless masses are coupled by a spring that absorbs the recoil energy as it is compressed by the movement and then expands providing energy for the rest of the operating cycle.
Since there is a minimum momentum required to operate a recoil-operated firearm's action, the cartridge must generate sufficient recoil to provide that momentum. Therefore, recoil-operated firearms work best with a cartridge that yields a momentum approximately equal to that for which the mechanism was optimized. For example, the M1911 design with factory springs is optimized for a 230-grain (15 g) bullet at factory velocity. Changes in caliber or drastic changes in bullet weight and/or velocity require modifications to spring weight or slide mass to compensate. Similarly the use of blank ammunition will typically cause the mechanism not to work correctly, unless a device is fitted to boost the recoil.
Recoil-operated designs are broadly categorized by how the parts move under recoil.
Long recoil operation is found primarily in shotguns, particularly ones based on John Browning's Auto-5 action. In 1885 a locked breech, long recoil action was patented by the Britons Schlund and Arthur. [9] In a long recoil action, the barrel and bolt remain locked together during recoil, compressing the recoil springs. Following this rearward movement, the bolt locks to the rear and the barrel is forced forward by its spring. The bolt is held in position until the barrel returns completely forward during which time the spent cartridge has been extracted and ejected, and a new shell has been positioned from the magazine. The bolt is released and forced closed by its recoil spring, chambering a fresh round.
The long recoil system was invented in the late 19th century and dominated the automatic shotgun market for more than half that century before it was supplanted by new gas-operated designs. While Browning halted production of the Auto-5 design in 1999, Franchi still makes a long-recoil–operated shotgun line, the AL-48, which shares both the original Browning action design, and the "humpbacked" appearance of the original Auto-5. Other weapons based on the Browning system were the Remington Model 8 semi-automatic rifle (1906), the Remington Model 11 & "The Sportsman" model (a model 11 with only a two-shell magazine) shotguns, the Frommer Stop line of pistols (1907), and the Chauchat automatic rifle (1915).
The short recoil action dominates the world of centerfire semi-automatic pistols, being found in nearly all weapons chambered for high-pressure pistol cartridges of 9×19mm Parabellum and larger, while low-pressure pistol cartridges of .380 ACP and smaller generally use the blowback method of operation. Short recoil operation differs from long recoil operation in that the barrel and bolt recoil together only a short distance before they unlock and separate. The barrel stops quickly, and the bolt continues rearward, compressing the recoil spring and performing the automated extraction and feeding process. During the last portion of its forward travel, the bolt locks into the barrel and pushes the barrel back into battery.
The method of locking and unlocking the barrel differentiates the wide array of short recoil designs. Most common are the John Browning tilting barrel designs based on either the swinging link and locking lugs as used in the M1911 pistol or the linkless cam design used in the Hi Power and CZ 75. Other designs are the locking block design found in the Walther P38 and Beretta 92, rollers in the MG42, or a rotating barrel used in the Beretta 8000 and others. An unusual variant is the toggle bolt design of the Borchardt C-93 and its descendant, the Luger pistol.
While the short recoil design is most common in pistols, the very first short-recoil–operated firearm was also the first machine gun, the Maxim gun. It used a toggle bolt similar to the one Borchardt later adapted to pistols. Vladimirov also used the short recoil principle in the Soviet KPV-14.5 heavy machine gun which has been in service with the Russian military and Middle Eastern armed forces since 1949. Melvin Johnson also used the short recoil principle in his M1941 rifle and M1941 Johnson machine gun.
An alternative design concept for recoil-operated firearms is the inertia operated system, the first practical use of it being the Sjögren shotgun, developed by Carl Axel Theodor Sjögren in the early 1900s, a Swedish engineer who was awarded a number of patents for his inertia operated design between 1900 and 1908 and sold about 5,000 automatic shotguns using the system in 1908–1909. [10] [11] In a reversal of the other designs, some inertia systems use nearly the entire firearm as the recoiling component, with only the bolt remaining stationary during firing. Because of this, the inertia system is only applied to heavily recoiling firearms, particularly shotguns. A similar system using inertia operation was then developed by Paolo Benelli in the early 1980s and patented in 1986. [12] With the exception of Sjögren's shotguns and rifles in the early 1900s, all inertia-operated firearms made until 2012 were either made by Benelli or used a design licensed from Benelli, such as the Franchi Affinity. Then the Browning Arms Company introduced the inertia-operated A5 (trademarked as Kinematic Drive) as successor to the long-recoil operated Auto-5. Both the Benelli and Browning systems are based on a rotating locking bolt, similar to that used in many gas-operated firearms.
Before firing, the bolt body is separated from the locked bolt head by a stiff spring. As the shotgun recoils after firing, inertia of the bolt body is large enough for it to remain stationary while the recoiling gun and locked bolt head move rearward. This movement compresses the spring between the bolt head and bolt body, storing the energy required to cycle the action. Since the spring can only be compressed a certain amount, this limits the amount of force the spring can absorb, and provides an inherent level of self-regulation to the action, allowing a wide range of shotshells to be used, from standard to magnum loads, as long as they provide the minimum recoil level to compress the spring. Note that the shotgun must be free to recoil for this to work—the compressibility of the shooter's body is sufficient to allow this movement, but firing the shotgun from a secure position in a rest or with the stock against the ground will not allow it to recoil sufficiently to operate the mechanism. Likewise, care must be exercised when modifying weapons of this type (e.g. addition of extended magazines or ammunition storage on the stock), as any sizable increase in weapon mass can reduce the work done from recoil below that required to cycle the action.
As the recoil spring returns to its uncompressed state, it pushes the bolt body backward with sufficient force to cycle the action. The bolt body unlocks and retracts the bolt head, extracts and ejects the cartridge, cocks the hammer, and compresses the return spring. Once the bolt reaches the end of its travel, the return spring provides the force to chamber the next round from the magazine, and lock the bolt closed.
Some short-recoil–operated firearms, such as the German MG 42 and MG 3, use a mechanism at the muzzle to extract some energy from the escaping powder gases to push the barrel backwards, in addition to the recoil energy. This boost provides higher rates of fire and/or more reliable operation. This type of mechanism is also found in some suppressors used on short recoil firearms, under the name gas assist or Nielsen device, where it is used to compensate for the extra mass the suppressor adds to the recoiling parts both by providing a boost and decoupling some of the suppressor's mass from the firearm's recoiling parts.
Muzzle boosters are also used on some recoil-operated firearms' blank-firing attachments to normalize the recoil force of a blank round (with no projectile) with the greater force of a live round, in order to allow the mechanism to cycle properly.
Several revolvers use recoil to cock the hammer and advance the cylinder. In these designs, the barrel and cylinder are affixed to an upper frame which recoils atop a sub-frame. As the upper receiver recoils, the cylinder is advanced and hammer cocked, functions that are usually done manually. Notable examples are the Webley–Fosbery and Mateba.
Other autoloading systems are:
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 slide on the majority of fully/semi-automatic pistols is the upper part that reciprocates ("slides") with recoil during the gun's operating cycle. It serves as the bolt carrier group (BCG) and partly as the receiver, and generally houses the firing pin/striker, the extractor and frequently also the barrel, and provides a mounting platform for iron and optical sights.
A repeating rifle is a single-barreled rifle capable of repeated discharges between each ammunition reload. This is typically achieved by having multiple cartridges stored in a magazine and then fed individually into the chamber by a reciprocating bolt, via either a manual or automatic action mechanism, while the act of chambering the round typically also recocks the hammer/striker for the following shot. In common usage, the term "repeating rifle" most often refers specifically to manual repeating rifles, as opposed to self-loading rifles, which use the recoil, gas, or blowback of the previous shot to cycle the action and load the next round, even though all self-loading firearms are technically a subcategory of repeating firearms.
Pump action is a type of manual firearm action that is operated by moving a sliding handguard on the gun's forestock. When shooting, the sliding forend is pulled rearward to eject any expended cartridge and typically to cock the hammer or striker, and then pushed forward to load a new cartridge into the chamber. Most pump-action firearms use an integral tubular magazine, although some do use detachable box magazines. Pump-action firearms are typically associated with shotguns, although it has been used in rifles, grenade launchers, as well as other types of firearms. A firearm using this operating mechanism is colloquially referred to as a pumpgun
Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gas created by the ignition of the propellant charge.
A breechblock is the part of the firearm action that closes the breech of a breech loading weapon before or at the moment of firing. It seals the breech and contains the pressure generated by the ignited propellant. Retracting the breechblock allows the chamber to be loaded with a cartridge.
Gas-operation is a system of operation used to provide energy to operate locked breech, autoloading firearms. In gas-operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to dispose of the spent case and insert a new cartridge into the chamber. Energy from the gas is harnessed through either a port in the barrel or a trap at the muzzle. This high-pressure gas impinges on a surface such as a piston head to provide motion for unlocking of the action, extraction of the spent case, ejection, cocking of the hammer or striker, chambering of a fresh cartridge, and locking of the action.
Rotating bolt is a method of locking the breech of a firearm closed for firing. Johann Nicolaus von Dreyse developed the first rotating bolt firearm, the "Dreyse needle gun", in 1836. The Dreyse locked using the bolt handle rather than lugs on the bolt head like the Mauser M 98 or M16. The first rotating bolt rifle with two lugs on the bolt head was the Lebel Model 1886 rifle. The concept has been implemented on most firearms chambered for high-powered cartridges since the 20th century.
Ferdinand Ritter von Mannlicher was an Austrian engineer and small arms designer. Along with James Paris Lee, Mannlicher was particularly noted for inventing the en-bloc clip charger-loading box magazine system. Later, while making improvements to other inventors' prototype designs for rotary-feed magazines, Mannlicher, together with his protégé Otto Schönauer, patented a perfected rotary magazine design, the Mannlicher–Schönauer rifle, which was a commercial and military success.
In firearms operating systems, the term roller locked refers to locking the bolt with rollers. Notable examples of firearms using this method are the MG 42 general-purpose machine gun, and the CZ 52 semi-automatic pistol. It was also applied in the experimental Gerät 03 semi-automatic rifle and Gerät 06 and EM-1 experimental assault rifles. The MG 42's lineage continued past World War II, forming the basis for the nearly identical MG1, chambered in 7.62×51mm NATO, which subsequently evolved into the MG1A3, and later the Bundeswehr's MG 3, Italian MG 42/59 and Austrian MG 74. It also spawned the Yugoslav unlicensed nearly identical Zastava M53.
A bolt is the part of a repeating, breechloading firearm that blocks the rear opening (breech) of the barrel chamber while the propellant burns, and moves back and forward to facilitate loading/unloading of cartridges from the magazine. The firing pin and extractor are often integral parts of the bolt. The terms "breechblock" and "bolt" are often used interchangeably or without a clear distinction, though usually, a bolt is a type of breechblock that has a nominally circular cross-section.
Locked breech is the design of a breech-reloading firearm's action. This is important in understanding how a self-reloading firearm works. In the simplest terms, the locked breech is one way to slow down the opening of the breech of a self-reloading firearm when fired. The source of power for the movement is recoil.
Break action is a type of firearm action in which the barrel(s) are hinged much like a door and rotate perpendicularly to the bore axis to expose the breech and allow loading and unloading of cartridges. A separate operation may be required for the cocking of a hammer to fire the new round. There are many types of break-action firearms; break actions are universal in double-barreled shotguns, double-barreled rifles, combination guns, and are commonly found in single shot pistols, rifles, shotguns, including flare guns, grenade launchers, air guns, and some older revolver designs. They are also known as hinge-action, break-open, break-barrel, break-top, or, on old revolvers, top-break actions.
Limp wristing is a phenomenon commonly encountered by semi-automatic pistol shooters, where the shooter's grip is not firm enough and the wrist is not held firm/straight enough to keep the frame of the firearm from traveling rearward while the bolt or slide of the firearm cycles. This condition often results in a failure to complete the operating cycle, properly termed a malfunction, but commonly termed a "jam". Both semi-automatic rifles and semi-automatic shotguns, if fired without the stock held against the shoulder correctly, may also be prone to limp wristing. Of the important variables involved in this type of malfunction, bullet and gas momentum, slide and barrel mass, recoil spring pre-load and spring rate, and shooting hand and arm mass are much more important than the compliance (limpness) of the wrist.
A muzzle booster or recoil booster is a device fixed to the muzzle of a firearm, intended to harness the energy of the escaping propellant to augment the force of recoil on portions of the firearm. In spite of its name, a muzzle booster does not increase muzzle force or velocity but instead is usually used to improve the reliability and/or rate of fire of a recoil operated firearm. It was invented by Hiram Maxim in 1894.
A blank-firing adapter or blank-firing attachment (BFA), sometimes called a blank adapter or blank attachment, is a device used in conjunction with blank ammunition for safety reasons, functional reasons or a combination of them both. Blank firing adapters are required for allowing blank ammunition to cycle the bolts of most semi-automatic and automatic firearms. It can also be a safety feature designed to break up the plugs replacing the bullet in military blanks as well as divert the hot gases from a blank discharge out to the sides, reducing the risk of injury to the target of an aimed shot.
The following are terms related to firearms and ammunition topics.
Benelli Raffaello CrioComfort is the name of a semi-automatic shotgun. It is manufactured by Italian arms manufacturer Benelli Armi SpA.
The Benelli Raffaello semi-automatic shotgun is manufactured by Italian arms manufacturer Benelli Armi SpA.
A repeating firearm or repeater is any firearm that is capable of being fired repeatedly before having to be manually reloaded with new ammunition into the firearm.
Friberg.
