Recoil operation is an operating mechanism used to implement
locked breech
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-reloadi ...
, autoloading
firearm
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 (see Legal definitions).
The first firearms originated in 10th-century China, when bamboo tubes ...
s. Recoil operated firearms use the energy of
recoil
Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force r ...
to cycle the action, as opposed to
gas operation
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 ...
or
blowback operation using the pressure of the propellant gas.
History
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. 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. Recoil-operation, if it was invented in 1663, would then lay 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
Cartridge may refer to:
Objects
* Cartridge (firearms), a type of modern ammunition
* ROM cartridge, a removable component in an electronic device
* Cartridge (respirator), a type of filter used in respirators
Other uses
* Cartridge (surname), a ...
(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. 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. In 1864 after the
Second Schleswig War
The Second Schleswig War ( da, Krigen i 1864; german: Deutsch-Dänischer Krieg) also sometimes known as the Dano-Prussian War or Prusso-Danish War was the second military conflict over the Schleswig-Holstein Question of the nineteenth century. T ...
, 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. 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. 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. Finally came Maxim's 1883 automatic recoil operated machine gun which introduced the modern age of automatic machine guns.
Design
The same forces that cause the
ejecta of a firearm (the projectile(s), propellant gas, wad,
sabot
Sabot may refer to:
* Sabot (firearms), disposable supportive device used in gunpowder ammunitions to fit/patch around a sub-caliber projectile
* Sabot (shoe), a type of wooden shoe
People
* Dick Sabot (1944–2005), American economist and busi ...
, etc.) to move down the
barrel
A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...
also cause all or a portion of the firearm to move in the opposite direction. The result is required by the
conservation of momentum
In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass an ...
such that the ejecta momentum and recoiling momentum are equal. These
momenta are calculated by:
: Ejecta mass × ejecta velocity = recoiling mass × recoil velocity
The
barrel
A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...
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
Inertia is the idea that an object will continue its current motion until some force causes its speed or direction to change. The term is properly understood as shorthand for "the principle of inertia" as described by Newton in his first law ...
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
Cartridge may refer to:
Objects
* Cartridge (firearms), a type of modern ammunition
* ROM cartridge, a removable component in an electronic device
* Cartridge (respirator), a type of filter used in respirators
Other uses
* Cartridge (surname), a ...
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
The M1911 (Colt 1911 or Colt Government) is a single-action, recoil-operated, semi-automatic pistol chambered for the .45 ACP cartridge. The pistol's formal U.S. military designation as of 1940 was ''Automatic Pistol, Caliber .45, M1911'' for th ...
design with factory springs is optimized for a 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
A blank is a firearm cartridge that, when fired, does not shoot a projectile like a bullet or pellet, but generates a muzzle flash and an explosive sound ( muzzle report) like a normal gunshot would. Firearms may need to be modified to allow a bl ...
will typically cause the mechanism not to work correctly, unless
a device is fitted to boost the recoil.
Categories
Recoil-operated designs are broadly categorized by how the parts move under recoil.
Long recoil
Long recoil operation is found primarily in
shotgun
A shotgun (also known as a scattergun, or historically as a fowling piece) is a long gun, long-barreled firearm designed to shoot a straight-walled cartridge (firearms), cartridge known as a shotshell, which usually discharges numerous small p ...
s, particularly ones based on
John Browning's
Auto-5
The Browning Automatic 5, most often Auto-5 or simply A-5, is a recoil-operated semi-automatic shotgun designed by John Browning. It was the first successful semi-automatic shotgun design, and remained in production until 1998. The name of the s ...
action. In 1885 a locked breech, long recoil action was patented by the Britons Schlund and Arthur. 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
The Remington Model 8 is a semi-automatic rifle designed by John Browning and produced by Remington Arms, introduced as the ''Remington Autoloading Rifle'' in 1905, though the name was changed to the ''Remington Model 8'' in 1911.
History
On Octo ...
semi-automatic rifle
A semi-automatic rifle is an autoloading rifle that fires a single cartridge with each pull of the trigger, and uses part of the fired cartridge's energy to eject the case and load another cartridge into the chamber. For comparison, a bolt-a ...
(1906), the Remington Model 11 & "The Sportsman" model (a model 11 with only a two-shell magazine) shotguns, the
Frommer Stop
The Frommer Stop is a Hungarian long-recoil, rotating bolt pistol manufactured by Fémáru, Fegyver és Gépgyár ( FÉG) (Metalware, Weapons and Machine Factory) in Budapest. It was designed by Rudolf Frommer, and its original design was adopte ...
line of pistols (1907), and the
Chauchat
The Chauchat ("show-sha", ) was the standard light machine gun or "machine rifle" of the French Army during World War I (1914–18). Its official designation was "Fusil Mitrailleur Modele 1915 CSRG" ("Machine Rifle Model 1915 CSRG"). Beginning i ...
automatic rifle (1915).
;Cycle diagram explanation
# Ready to fire position. Bolt is locked to barrel, both are fully forward.
# Recoil of firing forces bolt and barrel fully to the rear, compressing the return springs for both.
# Bolt is held to rear, while barrel unlocks and returns to battery under spring force. Fired round is ejected.
# Bolt returns under spring force, loads new round. Barrel locks in place as it returns to battery.
Short recoil
The short recoil action dominates the world of
centerfire
Two rounds of .357 Magnum, a centerfire cartridge; notice the circular primer in the center
A centerfire cartridge is a firearm metallic cartridge whose primer is located at the center of the base of its casing (i.e. "case head"). Unlike rim ...
semi-automatic pistol
A semi-automatic pistol is a type of repeating single-chamber handgun ( pistol) that automatically cycles its action to insert the subsequent cartridge into the chamber (self-loading), but requires manual actuation of the trigger to actuall ...
s, being found in nearly all weapons chambered for high-pressure pistol cartridges of
9×19mm Parabellum
The 9×19mm Parabellum (also known as 9mm Parabellum or 9mm Luger or simply 9mm) is a rimless, tapered firearms cartridge.
Originally designed by Austrian firearm designer Georg Luger in 1901, it is widely considered the most popular handgun a ...
and larger; while low-pressure pistol cartridges of
.380 ACP
The .380 ACP (9×17mm) ( Automatic Colt Pistol) is a rimless, straight-walled pistol cartridge developed by firearms designer John Moses Browning. The cartridge headspaces on the mouth of the case.Wilson, R. K. ''Textbook of Automatic Pisto ...
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
The M1911 (Colt 1911 or Colt Government) is a single-action, recoil-operated, semi-automatic pistol chambered for the .45 ACP cartridge. The pistol's formal U.S. military designation as of 1940 was ''Automatic Pistol, Caliber .45, M1911'' for th ...
pistol or the linkless cam design used in the
Hi Power and
CZ 75
The CZ 75 is a semi-automatic pistol made by Czech firearm manufacturer ČZUB. First introduced in 1975, it is one of the original " wonder nines" and features a staggered-column magazine, all-steel construction, and a hammer forged barrel. I ...
. Other designs are the locking block design found in the
Walther P38
The Walther P38 (originally written Walther P.38) is a 9 mm semi-automatic pistol that was developed by Carl Walther GmbH as the service pistol of the Wehrmacht at the beginning of World War II. It was intended to replace the costly Luger P08 ...
and
Beretta 92
The Beretta 92 (also Beretta 96 and Beretta 98) is a series of semi-automatic pistols designed and manufactured by Beretta of Italy. The Beretta 92 was designed in 1975, and production began in 1976. Many variants in several different calibers c ...
, rollers in the
MG42
The MG 42 (shortened from German: ''Maschinengewehr 42'', or "machine gun 42") is a German recoil-operated air-cooled general-purpose machine gun used extensively by the Wehrmacht and the Waffen-SS during the second half of World War II. Enterin ...
, or a rotating barrel used in the
Beretta 8000
The Beretta 8000 (Cougar) series pistols are manufactured by Beretta of Italy.
They first appeared on the market in 1994 as a more compact alternative to the full-sized Beretta 92 service pistol in order to offer a compromise between concealabil ...
and others. An unusual variant is the
toggle bolt
A toggle bolt, also known as a butterfly anchor, is a fastener for hanging objects on hollow walls such as drywall.
Toggle bolts have wings that open inside a hollow wall, bracing against it to hold the fastener securely.New Fix-it yourself manual ...
design of the
Borchardt C-93
The Borchardt C93 is a semi-automatic pistol designed by Hugo Borchardt in 1893.
The design is based upon the Maxim gun's toggle lock model.
Borchardt developed the high-velocity, bottlenecked 7.65×25mm Borchardt cartridge for the C93. His ...
and its descendant, the
Luger pistol
The Pistole Parabellum—or Parabellum-Pistole (Pistol Parabellum), commonly known as just Luger or Luger P08 is a toggle-locked recoil-operated semi-automatic pistol. The Luger was produced in several models and by several nations from 1898 ...
.
While the short recoil design is most common in pistols, the very first short-recoil–operated firearm was also the first
machine gun
A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) a ...
, the
Maxim gun
The Maxim gun is a recoil-operated machine gun invented in 1884 by Hiram Stevens Maxim. It was the first fully automatic machine gun in the world.
The Maxim gun has been called "the weapon most associated with imperial conquest" by historian ...
. 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
The M1941 Johnson Light Machine Gun, also known as the ''Johnson'' and the ''Johnny gun'', was an American recoil-operated light machine gun designed in the late 1930s by Melvin Johnson. It shared the same operating principle and many parts with ...
.
;Cycle diagram explanation
# Ready to fire position. Bolt is locked to barrel, both are fully forward.
# Upon firing, bolt and barrel recoil backwards a short distance while locked together. Near the end of the barrel travel, the bolt and barrel unlock.
# The barrel stops, but the unlocked bolt continues to move to the rear, ejecting the empty shell and compressing the recoil spring.
# The bolt returns forward under spring force, loading a new round into the barrel.
# Bolt locks into barrel, and forces barrel to return to battery.
Inertia
An alternative design concept for recoil-operated firearms is the inertia operated system, the first practical use of it being the
Sjögren shotgun
The Sjögren Inertia Shotgun is a 12 gauge semi-automatic shotgun that was designed by the Swedish inventor Carl Axel Theodor Sjögren, initially manufactured by AB Svenska Vapen- och Ammunitionsfabriken in SwedenЭ. Штейнгольд. Само ...
, 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. 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.
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 Benelli may refer to:
*Benelli Armi SpA, an Italian firearm manufacturer
*Benelli (motorcycles), an Italian motorcycle manufacturer
*HSR-Benelli, an Austrian-Italian manufacturer of personal watercraft
* Andrea Benelli (born 1960), Italian sports sh ...
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
The Browning Automatic 5, most often Auto-5 or simply A-5, is a recoil-operated semi-automatic shotgun designed by John Browning. It was the first successful semi-automatic shotgun design, and remained in production until 1998. The name of the s ...
. 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.
; Cycle diagram explanation
# Ready to fire position. Bolt is locked to barrel, both are fully forward.
# Upon firing, the firearm recoils backwards into the shooter's body. The inertial mass remains stationary, compressing a spring. The bolt remains locked to the barrel, which in turn is rigidly attached to the frame.
# The compressed spring forces the inertial mass rearwards until it transfers its momentum to the bolt.
# The bolt unlocks and moves to the rear, ejecting the fired round and compressing the return spring.
# The bolt returns to battery under spring force, loading a new round and locking into place.
# The shooter recovers from the shot, moving the firearm forward into position for the next shot.
Muzzle booster
Some short-recoil–operated firearms, such as the German
MG 42 and
MG 3
The MG3 is a small car produced by the Chinese automotive company SAIC. The first generation, marketed as the MG3 SW, is based on the British made Rover Streetwise, which itself was based on the Rover 25, while the second generation, introdu ...
, 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
suppressor
A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a muzzle device that reduces the acoustic intensity of the muzzle report (sound of a gunshot) and muzzle rise when a gun (firearm or air gun) is discharged, b ...
s 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 attachment
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 firin ...
s 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.
Automatic revolvers
Several
revolver
A revolver (also called a wheel gun) is a repeating handgun that has at least one barrel and uses a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold up to six roun ...
s 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
Mateba, a contraction of the Italian words Macchine Termo-Balistiche (Thermo-Ballistic Machines), was an Italian machine manufacturer based in Pavia, Italy. It is better known for its low-barrelled revolver pistols that it produced under the lead ...
.
Other autoloading systems
Other autoloading systems are:
*
Delayed blowback
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.
Several blowback systems exist wit ...
firearms uses an operation that delays the bolt opening until the gas pressure is at a safe level to extract.
*
Blow forward
Blow-forward is a firearm action where the propellant gas pressure and the friction of the bullet traveling down the bore drag the whole gun barrel forward to facilitate the opening of the breech. This forward barrel motion provides most of th ...
firearms lack the use of a bolt but instead a moving barrel that gets dragged forward by the bullet until it leaves the barrel to cycle its action.
*
Blowback firearms use the expanding gas impinging on the cartridge itself to push the bolt of the firearm rearward.
*
Gas-operated firearms tap off a small amount of the expanding gas to power the moving parts of the action.
See also
*
Bump stock
Bump stocks or bump fire stocks are gun stocks that can be used to assist in bump firing. Bump firing is the act of using the recoil of a semi-automatic firearm to fire ammunition cartridges in rapid succession.
The legality of bump stocks in ...
*
Slamfire
A slamfire is a discharge of a firearm occurring as a cartridge is being loaded into the chamber. Some firearms are designed to slamfire, but the term also describes a malfunction of self-loading firearms. Shooters accustomed to firearms requiring ...
References
Bibliography
*
External links
How Does it Work: Long RecoilForgotten Weapons
How Does it Work: Short RecoilForgotten Weapons
Animations and explanations of (short) recoil operation principle at howstuffworks.com
{{Firearms
Firearm actions
Artillery components