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Blowback (arms)
Encyclopedia
Blowback is a system of operation for self-loading
firearm
s that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gases created by the ignition of the propellant charge.
Several types of blowback systems exist within this broad principle of operation, each distinguished by the level of energy derived through the blowback principle and the methods used to control bolt movement. In most actions that use blowback operation, the breech is not locked mechanically at the time of firing: the inertia of the bolt and recoil spring(s), relative to the weight of the bullet, delays opening of the breech until the bullet has left the barrel. A few locked breech designs use a form of blowback (example: primer actuation) to perform the unlocking function.
Other operating principles for self-loading firearms include blow forward
, gas operation
, recoil operation
, Gatling
, and chain
. The blowback principle may be considered a simplified form of gas operation, since the cartridge case behaves like a piston driven by the powder gases.
What is common to all blowback systems is that the cartridge case must move under the direct action of the powder pressure, therefore any gun in which the bolt is not rigidly locked and permitted to move while there remains powder pressure in the chamber will undergo a degree of blowback action. The energy from the expansion of gases on firing appears in the form of kinetic energy transmitted to the bolt mechanism, which is controlled and used to operate the firearm's operation cycle. The extent to which blowback is employed largely depends on the manner used to control the movement of the bolt and the proportion of energy drawn from other systems of operation. It is with how the movement of the bolt is controlled where blowback systems differ. Blowback operation is most often divided into three categories, all using residual pressure to complete the cycle of operation: simple blowback, advanced primer ignition and delayed blowback or retarded blowback.
The simple (sometimes referred to as the "straight" or "pure") blowback system represents the most basic form of blowback operation and demonstrates the basic principles involved in the blowback cycle. The simple blowback mechanism typically consists of the bolt which rests against the base of the cartridge case and a recoil spring that is compressed by the kinetic energy of the bolt when it is thrown back in recoil. The stored energy of the compressed spring then drives the bolt back forward into firing position.
The cycle begins when the cartridge is fired. Expanding gases from the fired round send the projectile down the barrel and at the same time applies force to the case against the breech face of the bolt, overcoming the inertia of the bolt, resulting in a "blow back" effect. The forces exerted by the powder gases exist for only a relatively brief moment; lingering residual gases continue to act on the case for an even shorter period of time. The breech is kept sealed by the cartridge case until the bullet has left the barrel and gas pressure has dropped to a safe level; the inertia of the bolt mass ensures this (mass of the bolt + recoil spring, in some cases the hammer force too). At this point the powder pressure is zero and the force driving the bolt back is also zero, but the case and bolt continue to the rear of their own momentum. As the bolt travels back, the spent cartridge case is extracted and then ejected, and the firing mechanism is cocked while the bolt begins to decelerate against the resistance provided by the recoil or action spring. The bolt eventually reaches a velocity of zero and the kinetic energy from the recoil impulse is now stored in the compressed spring (some energy loss does occur due to friction and the extraction and ejection sequences). The action spring then propels the bolt forward again, which strips a round from the feed system along the way. The bolt carries a new cartridge into the chamber with considerable velocity and the action spring completes its energy transfer just prior to return to battery. The forward velocity is entirely dissipated upon impact with the chamber face.
To remain practical, this system is only suitable for firearms using relatively low pressure cartridges. Pure blowback operation is typically found on semi-automatic, small-caliber pistol
s, small-bore semi-automatic rifles and submachine gun
s. Some low-velocity cannon
and grenade launchers such as the Mk 19 grenade launcher
also use blowback operation.
The barrel of a blowback pistol is generally fixed to the frame and the slide
is held against the barrel only by the recoil spring tension. The slide starts to move rearward immediately upon ignition of the primer. As the cartridge moves rearward with the slide, it is extracted from the chamber and typically ejected clear of the firearm. The mass of the slide must be sufficient to hold the breech closed until the bullet exits the barrel and residual pressure is vented from the bore. A cartridge with too high a pressure or a slide with too little mass may cause the cartridge case to extract early, causing a separation or rupture. This generally limits blowback pistol designs to calibers less powerful than 9x19mm Parabellum (.25 ACP
, .32 ACP
, .380 ACP
, 9x18mm Makarov etc.). Any larger and the slide mass starts to become excessive, and therefore few blowback handguns in such calibers exist (see Recoil operation
(Short recoil operation) for the method most commonly used by these pistols); the most notable exceptions are simple, inexpensive guns such as those made by Hi-Point Firearms
which includes models chambered in .45 ACP
, .40 S&W
, .380 ACP
and 9x19mm Parabellum.
Most simple blowback rifles are chambered for the .22 Long Rifle
cartridge. Popular examples include the Marlin Model 60
and the Ruger 10/22
. Some blowback rifles or carbine
s are chambered for pistol cartridges, such as the 9mm Parabellum, .40 S&W and .45 ACP. Examples include the Ruger Police Carbine
, Beretta Cx4 Storm
, Marlin Camp Carbine
and Hi-Point Carbine. There were also a few rifles that chambered cartridges specifically designed for blowback operation. Examples include the Winchester Model 1905
, 1907
and 1910
. A very unusual blowback rifle was created by fitting the M1903 Springfield rifle with a mechanism called the Pedersen device
.
20-mm automatic cannon. It became a feature of a wide range of automatic weapons, including the Oerlikon
cannon widely used as anti-aircraft weapons during WWII. A simpler form of API blowback is very widely used on submachine guns.
In the API blowback design, the cartridge has not been fully chambered and the bolt is still moving forward when the primer ignited. In a plain blowback design, the propellant gases have to overcome static inertia
to accelerate the bolt rearwards to open the breech. In an API blowback, they also have to do the work of overcoming forward momentum
to stop the forward motion of the bolt. Because the forward and rearward speeds of the bolt tend to be approximately the same, the API blowback allows the weight of the bolt to be halved. Because the momentum of the two opposed bolt motions cancels out over time, the API blowback design results in reduced recoil.
The simplest form of API blowback is used in open bolt
submachine guns. In this configuration, the chamber depth is made a few thousandths of an inch shorter than the cartridge case's length. This causes the forward moving bolt's fixed firing pin to ignite the primer a moment before the bolt strikes the chamber face. While this simple version of the API design does not produce very important weight savings, it makes the firing cycle seem smoother to the operator and enhances controllability by reducing the submachine gun's muzzle climb
. The heavy telescoping bolt's center of mass is forward of the submachine gun's center of gravity at the point of cartridge ignition. The telescoping bolt's inertial action pushes the submachine gun's muzzle forward and down, thereby reducing felt recoil and countering the recoiling cartridge's attempt to make the muzzle rise.
To make full use of the potential advantages of advanced primer ignition, larger calibre APIB guns such as the Becker and Oerlikon use extended chambers, longer than is necessary to contain the round, and straight-sided cases with rebated rims. The last part of forward motion and the first part of the rearward motion of the case and bolt happen within the confines of this extended chamber. As long as the gas pressure in the barrel is high, the walls of case remain supported and the breach sealed, although the case is sliding rearwards. This sliding motion of the case, while it is expanded by a high internal gas pressure, risks tearing it apart, and a common solution is to grease the ammunition to reduce the friction. The case needs to have a rebated rim because the front end of the bolt will enter the chamber, and the extractor claw hooked over the rim therefore has to fit also within the diameter of the chamber. The case generally has very little neck, because this remains unsupported during the firing cycle and is generally deformed; a strongly necked case would be likely to split.
The API blowback design permits the use of more powerful ammunition in a lighter gun that would be achieved by using plain blowback, and the reduction of felt recoil results in further weight savings. The original Becker cannon, firing 20x70RB ammunition, was developed to be carried by WWI aircraft, and weighed only 30 kg. Oerlikon even produced an anti-tank rifle firing 20x110RB ammunition using the API blowback mechanism, the SSG36. On the other hand, because the design imposes a very close relationship between bolt mass, chamber length, spring strength, ammunition power and rate of fire, in APIB guns high rate of fire and high muzzle velocity tend to be mutually exclusive. API blowback guns also have to fire from an open bolt, which is not conducive to accuracy (although for short-ranged submachineguns this is less important) and means they can't be synchronized
to fire through a propeller.
and G3
, have fluted chambers to ease extraction. Below are various forms of delayed-blowback actions:
patented the first known design for a lever-delay system. The mechanism was adapted by Hungarian
arms designer Pál Király
(a.k.a. Paul de Kiraly) in the 1930s and first used in the Danuvia 43M
submachine gun
. Other weapons to use this system are the TKB-517
/2B-A-40
assault rifles, the AVB-7.62
battle rifle, the San Cristobal .30 carbine
, the FAMAS, the BSM/9 M1
and FNAB-43
submachine guns, the Hogue Avenger
and B76
pistols, the Sterling 7.62
and AA-52
machine guns.
Roller-delayed blowback was first used in the experimental MG 42 derivative MG 42V and the 1945 Mauser
StG 45 prototypes. Roller-delayed blowback operation differs from roller-locked recoil operation
as seen in the MG 42. Unlike the MG 42, in roller-delayed blowback the barrel is fixed and does not recoil. As the bolt head is driven rearward, rollers on the sides of the bolt are driven inward against a tapered bolt carrier extension. This forces the bolt carrier rearward at a much greater velocity and delays movement of the bolt head. The primary advantage of roller-delayed blowback is the simplicity of the design compared to gas or recoil operation.
After WWII, former Mauser technicians Ludwig Vorgrimler
and Theodor Löffler perfected this mechanism between 1946 and 1950 while working for the French Centre d'Etudes et d'Armament de Mulhouse (CEAM)
. The first full-scale production rifle to utilize roller-delay was the Spanish
CETME
followed by the Swiss Sturmgewehr 57, and the Heckler & Koch
G3 rifle. The MP5 submachine gun is the most common weapon in service worldwide still using this system. The P9 pistol
also uses roller-delayed blowback; however, the Czech vz. 52 is roller-locked. The Folded Delay Blowback (US Patent 6,079,138) applies roller delayed blowback to a bullpup weapon.
is never locked, and so is pushed rearward by the expanding propellant
gases as in other blowback-based designs. However, propellant gases are vented from the barrel into a cylinder with a piston that delays the opening of the bolt. It is used by Volkssturmgewehr 1-5
rifle, the Heckler & Koch P7, Steyr GB
and M-77B pistols.
pistol operates on this principle.
developed this simple method whereby the axis of bolt movement was not in line with that of the bore. The result was that a small rearward movement of the bolt in relation to the bore axis required a greater movement along the axis of bolt movement, essentially magnifying the resistance of the bolt without increasing its mass. The French MAS-38
submachine gun of 1938 utilizes a bolt whose path of recoil is at an angle to the barrel. The Jatimatic
and TDI Vector
use modified versions of this concept.
and Schwarzlose MG M.07/12
machine gun. Modern high-pressure blowback systems such as the HK G3 incorporate fluted chambers to facilitate extraction. Lacking fluted chambers, previous toggle-locked firearms required cases lubricated with wax (Pedersen) or oil (Schwarzlose).
's patented system uses a separate breech block within the slide or bolt carrier. When in battery, the breech block rests slightly forward of the locking shoulder in the frame. When the cartridge is fired, the bolt and slide move together a short distance rearward powered by the energy of the cartridge as in a standard blowback system. When the breech block contacts the locking shoulder, it stops, locking the breech in place. The slide continues rearward with the momentum it acquired in the initial phase. This allows chamber pressure to drop to safe levels while the breech is locked and the cartridge slightly extracted. Once the bullet leaves the barrel and pressure drops, the continuing motion of the slide lifts the breech block from its locking recess through a cam arrangement, continuing the firing cycle. The Remington 51
pistol and SIG MKMS
submachine gun were the only production firearms to utilize this type of operating system.
designed a rifle that operated on a similar principle around 1920 and submitted it for trials with the US Army. This rifle, submitted multiple times, competed unsuccessfully against the Pedersen
rifle and Garand
primer-actuated rifle in early testing to replace the M1903 Springfield rifle. Mikhail Kalashnikov
later developed a prototype submachine gun in 1942 that operated by a screw-delayed blowback principle, which is also found on the Fox Wasp carbine
. A pair of telescoping screws delayed rearward movement of the operating parts during the firing cycle. This weapon was ultimately not selected for production. The screw-delayed action is similar to the Blish lock
although Mannlicher's prototype pre-dates the Blish patent.
) developed a mechanism to allow firearms designed for full-sized cartridges to fire .22 caliber rimfire ammunition reliably. His system used a small 'piston' that incorporates the chamber. When the cartridge is fired, the front of the piston is thrust back with the cartridge giving a significant push to the bolt. Often described as accelerated blowback, this amplifies the otherwise anemic recoil energy of the .22 rimfire cartridge. Williams designed a training version of the Browning machine gun and the Colt Service Ace .22 long rifle version of the M1911
using his system. The floating chamber is both a blowback and gas operated mechanism.
were the first to develop the system in an unsuccessful bid to replace the M1903 bolt action rifle. (The U.S. military adopted ammunition with crimped primers that do not set back. Another Garand design was eventually accepted.) AAI Corporation used their developmental piston primer mechanism in a rifle submitted for the SPIW competition. A similar system is used in the spotting rifles on the LAW 80
and Shoulder-launched Multipurpose Assault Weapon
use a 9mm, .308 Winchester
based cartridge with a .22 Hornet
blank cartridge in place of the primer. Upon firing, the Hornet case sets back a short distance, unlocking the action.
. His locking mechanism was used in the Thompson submachine gun
, Autorifle
and Autocarbine
designs. This dubious principle was later eliminated as redundant in the .45 caliber submachine gun. Any actual advantage could also be attained by adding a mere ounce of mass to the bolt.
Semi-automatic firearm
A semi-automatic, or self-loading firearm is a weapon which performs all steps necessary to prepare the weapon to fire again after firing—assuming cartridges remain in the weapon's feed device or magazine...
firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
s that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gases created by the ignition of the propellant charge.
Several types of blowback systems exist within this broad principle of operation, each distinguished by the level of energy derived through the blowback principle and the methods used to control bolt movement. In most actions that use blowback operation, the breech is not locked mechanically at the time of firing: the inertia of the bolt and recoil spring(s), relative to the weight of the bullet, delays opening of the breech until the bullet has left the barrel. A few locked breech designs use a form of blowback (example: primer actuation) to perform the unlocking function.
Other operating principles for self-loading firearms include blow forward
Blow forward
Blow-forward is a firearm operation where the barrel is virtually the only moving part of the weapon that is forced forward against a spring by the cartridge pressure and friction of the projectile against the rifling...
, gas operation
Gas-operated reloading
Gas-operation is a system of operation used to provide energy to operate autoloading firearms. In gas-operation, a portion of high pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and chamber a new cartridge. Energy from the gas is harnessed...
, recoil operation
Recoil operation
Recoil operation is an operating mechanism used in locked-breech, autoloading firearms. As the name implies, these actions use the force of recoil to provide energy to cycle the action...
, Gatling
Gatling gun
The Gatling gun is one of the best known early rapid-fire weapons and a forerunner of the modern machine gun. It is well known for its use by the Union forces during the American Civil War in the 1860s, which was the first time it was employed in combat...
, and chain
Chain gun
A chain gun is a type of machine gun or autocannon that uses an external source of power, rather than diverting energy from the cartridge, to cycle the weapon, and does so via a continuous loop of chain similar to that used on a motorcycle or bicycle. "Chain gun" is a registered trademark of...
. The blowback principle may be considered a simplified form of gas operation, since the cartridge case behaves like a piston driven by the powder gases.
Principle of operation
The blowback system is generally defined as an operating system in which energy to operate the firearm's various mechanisms and provide automation is derived from the movement of the spent cartridge case pushed out of the chamber by rapidly expanding powder gases. This rearward thrust, imparted against the bolt, is a direct reaction of the total reaction to the forward thrust applied to the bullet and the expansion of propellant gases. Certain guns will use all of the energy from blowback to perform the entire operating cycle (these are typically designs using relatively "low power" ammunition) while others will use only a portion of the blowback to operate certain parts of the cycle or simply use the blowback energy to enhance the operational energy from another system of automatic operation.What is common to all blowback systems is that the cartridge case must move under the direct action of the powder pressure, therefore any gun in which the bolt is not rigidly locked and permitted to move while there remains powder pressure in the chamber will undergo a degree of blowback action. The energy from the expansion of gases on firing appears in the form of kinetic energy transmitted to the bolt mechanism, which is controlled and used to operate the firearm's operation cycle. The extent to which blowback is employed largely depends on the manner used to control the movement of the bolt and the proportion of energy drawn from other systems of operation. It is with how the movement of the bolt is controlled where blowback systems differ. Blowback operation is most often divided into three categories, all using residual pressure to complete the cycle of operation: simple blowback, advanced primer ignition and delayed blowback or retarded blowback.
Simple blowback
The cycle begins when the cartridge is fired. Expanding gases from the fired round send the projectile down the barrel and at the same time applies force to the case against the breech face of the bolt, overcoming the inertia of the bolt, resulting in a "blow back" effect. The forces exerted by the powder gases exist for only a relatively brief moment; lingering residual gases continue to act on the case for an even shorter period of time. The breech is kept sealed by the cartridge case until the bullet has left the barrel and gas pressure has dropped to a safe level; the inertia of the bolt mass ensures this (mass of the bolt + recoil spring, in some cases the hammer force too). At this point the powder pressure is zero and the force driving the bolt back is also zero, but the case and bolt continue to the rear of their own momentum. As the bolt travels back, the spent cartridge case is extracted and then ejected, and the firing mechanism is cocked while the bolt begins to decelerate against the resistance provided by the recoil or action spring. The bolt eventually reaches a velocity of zero and the kinetic energy from the recoil impulse is now stored in the compressed spring (some energy loss does occur due to friction and the extraction and ejection sequences). The action spring then propels the bolt forward again, which strips a round from the feed system along the way. The bolt carries a new cartridge into the chamber with considerable velocity and the action spring completes its energy transfer just prior to return to battery. The forward velocity is entirely dissipated upon impact with the chamber face.
To remain practical, this system is only suitable for firearms using relatively low pressure cartridges. Pure blowback operation is typically found on semi-automatic, small-caliber pistol
Handgun
A handgun is a firearm designed to be held and operated by one hand. This characteristic differentiates handguns as a general class of firearms from long guns such as rifles and shotguns ....
s, small-bore semi-automatic rifles and submachine gun
Submachine gun
A submachine gun is an automatic carbine, designed to fire pistol cartridges. It combines the automatic fire of a machine gun with the cartridge of a pistol. The submachine gun was invented during World War I , but the apex of its use was during World War II when millions of the weapon type were...
s. Some low-velocity cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
and grenade launchers such as the Mk 19 grenade launcher
Mk 19 grenade launcher
The Mk 19 Grenade Launcher is a 40 mm belt-fed automatic grenade launcher or grenade machine gun that entered U.S. military service during the Cold War, first seeing action during the Vietnam War and remaining in service today.-Overview:...
also use blowback operation.
The barrel of a blowback pistol is generally fixed to the frame and the slide
Pistol slide
The slide is the part of the weapon on a majority of semi-automatic pistols that moves during the operating cycle and generally houses the firing pin or striker and the extractor, and serves as the bolt...
is held against the barrel only by the recoil spring tension. The slide starts to move rearward immediately upon ignition of the primer. As the cartridge moves rearward with the slide, it is extracted from the chamber and typically ejected clear of the firearm. The mass of the slide must be sufficient to hold the breech closed until the bullet exits the barrel and residual pressure is vented from the bore. A cartridge with too high a pressure or a slide with too little mass may cause the cartridge case to extract early, causing a separation or rupture. This generally limits blowback pistol designs to calibers less powerful than 9x19mm Parabellum (.25 ACP
.25 ACP
The .25 ACP centerfire pistol cartridge is a semi-rimmed, straight-walled pistol cartridge introduced by John Browning in 1905 alongside the Fabrique Nationale model 1905 pistol...
, .32 ACP
.32 ACP
.32 ACP , also known as the .32 Automatic is a pistol cartridge. It is a semi-rimmed, straight-walled cartridge developed by firearms designer John Browning, initially for use in the FN M1900 semi-automatic pistol...
, .380 ACP
.380 ACP
The .380 ACP pistol cartridge is a rimless, straight-walled pistol cartridge developed by firearms designer John Browning. The cartridge headspaces on the mouth of the case. It was introduced in 1908 by Colt, and has been a popular self-defense cartridge ever since...
, 9x18mm Makarov etc.). Any larger and the slide mass starts to become excessive, and therefore few blowback handguns in such calibers exist (see Recoil operation
Recoil operation
Recoil operation is an operating mechanism used in locked-breech, autoloading firearms. As the name implies, these actions use the force of recoil to provide energy to cycle the action...
(Short recoil operation) for the method most commonly used by these pistols); the most notable exceptions are simple, inexpensive guns such as those made by Hi-Point Firearms
Hi-Point Firearms
Hi-Point Firearms, also known as Beemiller , is a firearms manufacturer based in Mansfield, Ohio. However only the CF.380, C9 9 mm, & the carbines are made in Mansfield...
which includes models chambered in .45 ACP
.45 ACP
The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...
, .40 S&W
.40 S&W
The .40 S&W is a rimless pistol cartridge developed jointly by major American firearms manufacturers Winchester and Smith & Wesson. The .40 S&W was developed from the ground up as a law enforcement cartridge designed to duplicate performance of the FBI's reduced velocity 10mm cartridge which could...
, .380 ACP
.380 ACP
The .380 ACP pistol cartridge is a rimless, straight-walled pistol cartridge developed by firearms designer John Browning. The cartridge headspaces on the mouth of the case. It was introduced in 1908 by Colt, and has been a popular self-defense cartridge ever since...
and 9x19mm Parabellum.
Most simple blowback rifles are chambered for the .22 Long Rifle
.22 Long Rifle
The .22 Long Rifle rimfire cartridge is a long established variety of ammunition, and in terms of units sold is still by far the most common in the world today. The cartridge is often referred to simply as .22 LR and various rifles, pistols, revolvers, and even some smoothbore shotguns have...
cartridge. Popular examples include the Marlin Model 60
Marlin Model 60
The Marlin Model 60, also known as the Marlin Glenfield Model 60, is a semi-automatic rifle that fires the .22 LR rimfire cartridge. Produced by the Marlin Firearms Company of North Haven, Connecticut, it has been in continuous production since 1960 and the company claims it is the most popular of...
and the Ruger 10/22
Ruger 10/22
The Ruger 10/22 is a semi-automatic rimfire rifle chambered in .22 Long Rifle. It has a removable 10-round rotary magazine which allows the magazine to fit flush with the bottom of the stock. Higher capacity magazines are also available...
. Some blowback rifles or carbine
Carbine
A carbine , from French carabine, is a longarm similar to but shorter than a rifle or musket. Many carbines are shortened versions of full rifles, firing the same ammunition at a lower velocity due to a shorter barrel length....
s are chambered for pistol cartridges, such as the 9mm Parabellum, .40 S&W and .45 ACP. Examples include the Ruger Police Carbine
Ruger Police Carbine
The Ruger Carbine, or the ruger police carbine, is a pistol caliber carbine designed as a companion to the Ruger P Series pistols. As of 2007, Ruger has discontinued production citing low demand. It is a semi-automatic carbine using a blowback action...
, Beretta Cx4 Storm
Beretta Cx4 Storm
The Beretta Cx4 Storm is a pistol-caliber carbine aimed at the sporting, personal defense and law enforcement markets. Seven different models accept full-size Beretta magazines from the 92/96, Cougar, and Px4 series pistols in 9x21 IMI , 9x19mm Parabellum, .40 S&W and .45 ACP.The Beretta Cx4 Storm...
, Marlin Camp Carbine
Marlin Camp Carbine
The Marlin Camp Carbine is a self-loading carbine chambered for either 9mm Parabellum or .45 ACP, formerly manufactured by Marlin Firearms Company of North Haven, Connecticut. The carbine has been discontinued since 1999....
and Hi-Point Carbine. There were also a few rifles that chambered cartridges specifically designed for blowback operation. Examples include the Winchester Model 1905
Winchester Model 1905
The Winchester Model 1905 , is a blowback-operated, semi-automatic rifle produced by the Winchester Repeating Arms Company beginning in 1905 and discontinued in 1920. This rifle loads cartridges from a 5 or 10-round capacity, detachable box magazine located immediately forward of the trigger guard...
, 1907
Winchester Model 1907
The Winchester Model 1907 , is a blowback-operated, semi-automatic rifle produced by the Winchester Repeating Arms Company beginning in 1906 with production ending in 1958. It was fed from a 5 or 10-round capacity, detachable box magazine located immediately forward of the trigger guard...
and 1910
Winchester Model 1910
The Winchester Model 1910 is a blowback operated semi-automatic rifle rifle produced by the Winchester Repeating Arms Company beginning in 1910 with production ending in 1936. This rifle is fed from a 4-round capacity, detachable box magazine located immediately forward of the trigger guard...
. A very unusual blowback rifle was created by fitting the M1903 Springfield rifle with a mechanism called the Pedersen device
Pedersen device
The Pedersen Device is an attachment developed during World War I for the M1903 Springfield rifle that allowed it to fire a short .30 Caliber intermediate cartridge in semi-automatic mode...
.
Advanced Primer Ignition blowback
Advanced Primer Ignition (API) was originally developed by Reinhold Becker for use on the Becker20 mm Becker
The 20 mm Becker was a German automatic cannon developed for aircraft use during World War I. It was first mass produced in 1916 and was installed in a variety of aircraft; the only German autocannon to actually see service in the air during the war....
20-mm automatic cannon. It became a feature of a wide range of automatic weapons, including the Oerlikon
Oerlikon 20 mm cannon
The Oerlikon 20 mm cannon is a series of autocannons, based on an original design by Reinhold Becker of Germany, very early in World War I, and widely produced by Oerlikon Contraves and others...
cannon widely used as anti-aircraft weapons during WWII. A simpler form of API blowback is very widely used on submachine guns.
In the API blowback design, the cartridge has not been fully chambered and the bolt is still moving forward when the primer ignited. In a plain blowback design, the propellant gases have to overcome static inertia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...
to accelerate the bolt rearwards to open the breech. In an API blowback, they also have to do the work of overcoming forward momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
to stop the forward motion of the bolt. Because the forward and rearward speeds of the bolt tend to be approximately the same, the API blowback allows the weight of the bolt to be halved. Because the momentum of the two opposed bolt motions cancels out over time, the API blowback design results in reduced recoil.
The simplest form of API blowback is used in open bolt
Open bolt
A semi or full automatic firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear. When the trigger is pulled the bolt goes forward, feeding a round from the magazine into the chamber and firing it...
submachine guns. In this configuration, the chamber depth is made a few thousandths of an inch shorter than the cartridge case's length. This causes the forward moving bolt's fixed firing pin to ignite the primer a moment before the bolt strikes the chamber face. While this simple version of the API design does not produce very important weight savings, it makes the firing cycle seem smoother to the operator and enhances controllability by reducing the submachine gun's muzzle climb
Muzzle climb
Muzzle climb refers to the elevation of muzzle of automatic and rapid-fire semi-automatic firearms caused by combined recoil from multiple shots being fired in quick succession....
. The heavy telescoping bolt's center of mass is forward of the submachine gun's center of gravity at the point of cartridge ignition. The telescoping bolt's inertial action pushes the submachine gun's muzzle forward and down, thereby reducing felt recoil and countering the recoiling cartridge's attempt to make the muzzle rise.
To make full use of the potential advantages of advanced primer ignition, larger calibre APIB guns such as the Becker and Oerlikon use extended chambers, longer than is necessary to contain the round, and straight-sided cases with rebated rims. The last part of forward motion and the first part of the rearward motion of the case and bolt happen within the confines of this extended chamber. As long as the gas pressure in the barrel is high, the walls of case remain supported and the breach sealed, although the case is sliding rearwards. This sliding motion of the case, while it is expanded by a high internal gas pressure, risks tearing it apart, and a common solution is to grease the ammunition to reduce the friction. The case needs to have a rebated rim because the front end of the bolt will enter the chamber, and the extractor claw hooked over the rim therefore has to fit also within the diameter of the chamber. The case generally has very little neck, because this remains unsupported during the firing cycle and is generally deformed; a strongly necked case would be likely to split.
The API blowback design permits the use of more powerful ammunition in a lighter gun that would be achieved by using plain blowback, and the reduction of felt recoil results in further weight savings. The original Becker cannon, firing 20x70RB ammunition, was developed to be carried by WWI aircraft, and weighed only 30 kg. Oerlikon even produced an anti-tank rifle firing 20x110RB ammunition using the API blowback mechanism, the SSG36. On the other hand, because the design imposes a very close relationship between bolt mass, chamber length, spring strength, ammunition power and rate of fire, in APIB guns high rate of fire and high muzzle velocity tend to be mutually exclusive. API blowback guns also have to fire from an open bolt, which is not conducive to accuracy (although for short-ranged submachineguns this is less important) and means they can't be synchronized
Interrupter gear
An interrupter gear is a device used on military aircraft and warships in order to allow them to target opponents without damaging themselves....
to fire through a propeller.
Delayed blowback
For more powerful rounds or for a lighter operating mechanism, some system of delayed or retarded blowback is often used, requiring the bolt to overcome some initial resistance while not fully locked. Because of high pressures, rifle-caliber delayed blowback firearms, such as the FAMASFAMAS
The FAMAS is a bullpup-styled assault rifle designed and manufactured in France by MAS located in Saint-Étienne, which is now a member of the French government-owned Nexter group...
and G3
Heckler & Koch G3
The G3 is a 7.62mm battle rifle developed in the 1950s by the German armament manufacturer Heckler & Koch GmbH in collaboration with the Spanish state-owned design and development agency CETME ....
, have fluted chambers to ease extraction. Below are various forms of delayed-blowback actions:
Lever delayed
Lever-delayed blowback utilizes leverage to delay the opening of the breech. When the cartridge pushes against the bolt face, the lever moves the bolt carrier rearward at an accelerated rate relative to the light bolt. This leverage significantly increases resistance and slows the movement of the lightweight bolt. John PedersenJohn Pedersen
John Douglas Pedersen was a prolific arms designer who worked for Remington Arms, and later for the United States Government. Famed gun designer John Moses Browning told Maj. Gen. Julian S. Hatcher of U.S...
patented the first known design for a lever-delay system. The mechanism was adapted by Hungarian
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
arms designer Pál Király
Pál Király
Pál Király is an Hungarian engineer and weapons designer.-Work & Designs:He is best known for development of lever-delayed blowback firearms. He designed the Danuvia 39M and improved it into the Danuvia 43M Submachine gun...
(a.k.a. Paul de Kiraly) in the 1930s and first used in the Danuvia 43M
Danuvia 43M
The 9x25 mm Danuvia submachine guns were designed by Hungarian engineer Pál Király in the late 1930s. They were issued to Hungarian army troops in 1939 and remained in service throughout World War II. A total of roughly 8,000 were made between 1939 and 1945. The Danuvia was a large, sturdy weapon,...
submachine gun
Submachine gun
A submachine gun is an automatic carbine, designed to fire pistol cartridges. It combines the automatic fire of a machine gun with the cartridge of a pistol. The submachine gun was invented during World War I , but the apex of its use was during World War II when millions of the weapon type were...
. Other weapons to use this system are the TKB-517
TKB-517
The TKB-517 assault rifle was designed by German A. Korobov. This rifle was similar externally to the AK-47 but turned out to be more reliable and accurate, and easier to produce and maintain . Like the AK series, it was also manufactured with folding stocks, long heavier barrels with bipods...
/2B-A-40
2B-A-40
The 2B-A-40 is an assault rifle of Russian origin. The weapon uses a delayed blowback operation and is chambered in the 7.62x39mm round. The 2B-A-40 also came as a light machine gun as the 2B-P-40.-See Also:*AVB-7.62*ČZW-556/ČZW-762*FAMAS*TKB-517...
assault rifles, the AVB-7.62
AVB-7.62
The AB-5.45, AB-7.62, AVB-7.62, and LCZ B20 are a series of weapons developed by Russian small arms designer Anatoly F. Baryshev from the 1960s to late 1990s. The mechanism developed by Baryshev allows the latter two of these light weapons to fire full powered rifle ammunition and still be...
battle rifle, the San Cristobal .30 carbine
Cristobal (carbine)
The .30 Kiraly-Cristobal carbine, also known as the San Cristobal or Cristobal automatic rifle was manufactured by the Dominican Republic’s Armeria San Cristobal Weapon Factory....
, the FAMAS, the BSM/9 M1
BSM/9 M1
The BSM/9 M1 is a Brazilian inertia-delayed blowback-operated, selective-fire submachine-gun developed during the late 1970s, chambered for the 9x19mm Parabellum round which uses 20/32-round Uzi-compatible box magazines. It has a cyclic rate of 600 rounds per minute and a muzzle velocity of 400...
and FNAB-43
FNAB-43
The FNAB-43 is an Italian designed and developed submachinegun manufactured from 1943 to 1944. The first prototype was built in 1942 and the 7,000 built by the FNA-B were issued to German and Italian RSI units fighting in Northern Italy...
submachine guns, the Hogue Avenger
Hogue Avenger
The Hogue Avenger is a fixed barrel M1911 derivative that uses a lever-delayed blowback operation....
and B76
Benelli B76
The B76 is a pistol manufactured in Italy by Benelli. It operates on the lever-delayed blowback system that Benelli called an "inertia lock". Despite the name, the system of operation is pure lever-delayed as explained in . Manufacture has been discontinued....
pistols, the Sterling 7.62
Sterling 7.62
The Sterling 7.62 was a Battle rifle/Light machine gun variant of the Sterling submachine gun which was manufactured in the 7.62x51mm NATO calibre. It used lever-delayed blowback to handle the more powerful rounds and was fed from 30 round Bren magazines as well as 20 round magazines from L1A1 SLR's...
and AA-52
AA-52
The AA-52 is one of the first French-produced guns of the post World War II era. It was manufactured by MAS...
machine guns.
Roller delayed
Mauser
Mauser was a German arms manufacturer of a line of bolt-action rifles and pistols from the 1870s to 1995. Mauser designs were built for the German armed forces...
StG 45 prototypes. Roller-delayed blowback operation differs from roller-locked recoil operation
Recoil operation
Recoil operation is an operating mechanism used in locked-breech, autoloading firearms. As the name implies, these actions use the force of recoil to provide energy to cycle the action...
as seen in the MG 42. Unlike the MG 42, in roller-delayed blowback the barrel is fixed and does not recoil. As the bolt head is driven rearward, rollers on the sides of the bolt are driven inward against a tapered bolt carrier extension. This forces the bolt carrier rearward at a much greater velocity and delays movement of the bolt head. The primary advantage of roller-delayed blowback is the simplicity of the design compared to gas or recoil operation.
After WWII, former Mauser technicians Ludwig Vorgrimler
Ludwig Vorgrimler
Dr. Ludwig Vorgrimler is the man most commonly associated with the design of the Spanish CETME rifle, and its prolific roller-delayed offspring from the German gunmaker Heckler & Koch such as the G3 and MP5.- Early career :Vorgrimler worked as an engineer for several arms manufacturers over his...
and Theodor Löffler perfected this mechanism between 1946 and 1950 while working for the French Centre d'Etudes et d'Armament de Mulhouse (CEAM)
Atelier Mécanique de Mulhouse
Atelier Mécanique de Mulhouse , formerly known as Centre d'Études et d'Armement de Mulhouse , was a French weapons manufacturer that operated from 1946 to 1967.-History:...
. The first full-scale production rifle to utilize roller-delay was the Spanish
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
CETME
CETME
CETME is an acronym for Centro de Estudios Técnicos de Materiales Especiales , a Spanish government design and development establishment. While being involved in many projects CETME was mostly known for its small arms research and development...
followed by the Swiss Sturmgewehr 57, and the Heckler & Koch
Heckler & Koch
Heckler & Koch GmbH is a German defense manufacturing company that produces various small arms. Some of their products include the SA80, MP5 submachine gun, G3 automatic rifle, the G36 assault rifle, the HK 416, the MP7 personal defense weapon, the USP series of handguns, and the high-precision...
G3 rifle. The MP5 submachine gun is the most common weapon in service worldwide still using this system. The P9 pistol
Heckler & Koch P9
The HK P9 is a semi-automatic pistol from Heckler & Koch in 9 mm Parabellum and the first to use a variation of H&K's roller delayed blowback system in a pistol format and polygonal rifling now common in H&K designs. Designed in 1965 and produced between 1969 and 1978, only 485 of these pistols...
also uses roller-delayed blowback; however, the Czech vz. 52 is roller-locked. The Folded Delay Blowback (US Patent 6,079,138) applies roller delayed blowback to a bullpup weapon.
Gas delayed
Gas-delayed blowback should not be confused with gas-operated. The boltBolt (firearm)
A bolt is a mechanical part of a firearm that blocks the rear of the chamber while the propellant burns.In manually-operated firearms, such as bolt-action, lever-action, and pump-action rifles and shotguns, the bolt is held fixed by its locking lugs during firing, forcing all the expanding gas...
is never locked, and so is pushed rearward by the expanding propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...
gases as in other blowback-based designs. However, propellant gases are vented from the barrel into a cylinder with a piston that delays the opening of the bolt. It is used by Volkssturmgewehr 1-5
Volkssturmgewehr 1-5
The Volkssturmgewehr 1-5 is a set of 5 rifle designs developed by Nazi Germany during the last months of World War II...
rifle, the Heckler & Koch P7, Steyr GB
Steyr GB
The Steyr GB, is a double-action 9×19mm Parabellum caliber, large-framed semi-automatic pistol. The GB uses a gas-delayed blowback action and has a magazine capacity of 18 rounds...
and M-77B pistols.
Chamber-ring delayed
When a cartridge is fired, the case expands to seal the sides of the chamber. This seal prevents high-pressure gas from escaping into the action of the gun. Because a conventional chamber is slightly oversized, an unfired cartridge will enter freely. In a chamber-ring delayed firearm, the chamber is conventional in every respect except for a raised portion at the rear of smaller diameter than the front of the chamber. When the case expands in the front of the chamber and pushes rearward on the slide, it is slowed as this raised portion constricts the expanded portion of the case as the case is extracted. The SeecampSeecamp
L. W. Seecamp Co., Inc. is a manufacturer of hand made pocket pistols located in Milford, Connecticut from 1981 to present.L. W. Seecamp Co., Inc. was started as a pistolsmithing company in 1973 specializing in double action conversions for the 1911 Colt .45...
pistol operates on this principle.
Off-axis bolt travel
John BrowningJohn Browning
John Moses Browning , born in Ogden, Utah, was an American firearms designer who developed many varieties of military and civilian firearms, cartridges, and gun mechanisms, many of which are still in use around the world...
developed this simple method whereby the axis of bolt movement was not in line with that of the bore. The result was that a small rearward movement of the bolt in relation to the bore axis required a greater movement along the axis of bolt movement, essentially magnifying the resistance of the bolt without increasing its mass. The French MAS-38
MAS-38
The MAS-38 was a French submachine gun designed prior to the Second World War and used by French and German forces.It derived from a small arms development program that took place between 1918 and 1922 under the control of the Service Technique de l'Armement. A submachine gun, a light machine gun...
submachine gun of 1938 utilizes a bolt whose path of recoil is at an angle to the barrel. The Jatimatic
JaTiMatic
The Jatimatic is a Finnish 9 mm submachine gun developed in the late 1970s and early 1980s by Jali Timari. The submachine gun made its debut in 1983. The Jatimatic was manufactured in very limited numbers initially by Tampereen Asepaja Oy of Tampere and later—Oy Golden Gun Ltd...
and TDI Vector
TDI Vector
The KRISS Vector series is a family of NFA and non-NFA weapons based upon the parent submachine gun design developed by KRISS USA. KRISS USA is formerly known as Transformational Defense Industries . They utilize asymmetrical recoil and in-line design to reduce recoil and muzzle climb.- Design...
use modified versions of this concept.
Toggle delayed
In toggle-delayed blowback firearms, the rearward motion of the breechblock must overcome significant mechanical leverage. The bolt is hinged in the middle, stationary at the rear end and nearly straight at rest. As the breech moves back under blowback power, the hinge joint moves upward. The leverage disadvantage keeps the breech from opening until the bullet has left the barrel and pressures have dropped to a safe level. This mechanism was used on the Luger rifle, the Pedersen riflePedersen rifle
The Pedersen Rifle, officially known in final form as the T1E3 rifle, was a United States semi-automatic rifle designed by John Pedersen that was made in small numbers for testing by the United States Army during the 1920s as part of a program to standardize and adopt a replacement for the M1903...
and Schwarzlose MG M.07/12
Schwarzlose MG M.07/12
The Maschinengewehr Patent Schwarzlose M.07/12 was a medium machine-gun, and was used as a standard issue firearm in the Austro-Hungarian Army throughout World War I. It was also used by the Dutch, Greek and Hungarian armies during World War II...
machine gun. Modern high-pressure blowback systems such as the HK G3 incorporate fluted chambers to facilitate extraction. Lacking fluted chambers, previous toggle-locked firearms required cases lubricated with wax (Pedersen) or oil (Schwarzlose).
Hesitation locked
John PedersenJohn Pedersen
John Douglas Pedersen was a prolific arms designer who worked for Remington Arms, and later for the United States Government. Famed gun designer John Moses Browning told Maj. Gen. Julian S. Hatcher of U.S...
's patented system uses a separate breech block within the slide or bolt carrier. When in battery, the breech block rests slightly forward of the locking shoulder in the frame. When the cartridge is fired, the bolt and slide move together a short distance rearward powered by the energy of the cartridge as in a standard blowback system. When the breech block contacts the locking shoulder, it stops, locking the breech in place. The slide continues rearward with the momentum it acquired in the initial phase. This allows chamber pressure to drop to safe levels while the breech is locked and the cartridge slightly extracted. Once the bullet leaves the barrel and pressure drops, the continuing motion of the slide lifts the breech block from its locking recess through a cam arrangement, continuing the firing cycle. The Remington 51
Remington 51
The Remington 51 is a small pocket pistol designed by John Pedersen and manufactured by Remington Arms in the early 20th century for the American civilian market...
pistol and SIG MKMS
SIG MKMS
The SIG MKMS was sub-machine gun designed by Schweizerische_Industrie_Gesellschaft company in Neuhausen during the early 1930s and was first introduced in 1933. It was designed for the military and to increase firepower it had a larger capacity magazine as well as a longer barrel, one that would...
submachine gun were the only production firearms to utilize this type of operating system.
Screw-delayed
First used on the Mannlicher retarded blowback rifle of 1893, the bolt in screw-delayed blowback was slowed by the need to rotate steeply pitched interrupted threads on the bolt and receiver. John T. ThompsonJohn T. Thompson
John Taliaferro Thompson, , was a United States Army officer best remembered as the inventor of the Thompson submachine gun.-Early life:...
designed a rifle that operated on a similar principle around 1920 and submitted it for trials with the US Army. This rifle, submitted multiple times, competed unsuccessfully against the Pedersen
John Pedersen
John Douglas Pedersen was a prolific arms designer who worked for Remington Arms, and later for the United States Government. Famed gun designer John Moses Browning told Maj. Gen. Julian S. Hatcher of U.S...
rifle and Garand
John Garand
John Cantius Garand was a designer of firearms best known for creating the first successful semi-automatic rifle to be widely used in active military service, the M1 Garand....
primer-actuated rifle in early testing to replace the M1903 Springfield rifle. Mikhail Kalashnikov
Mikhail Kalashnikov
Lieutenant General Mikhail Timofeyevich Kalashnikov is a Russian small arms designer, most famous for designing the AK-47 assault rifle, the AKM and the AK-74.-Early life:...
later developed a prototype submachine gun in 1942 that operated by a screw-delayed blowback principle, which is also found on the Fox Wasp carbine
Demro TAC-1
The Demro TAC-1 is a semi-automatic carbine chambered in either .45 ACP or 9x19mm Parabellum. It is visually similar to the Thompson submachine gun...
. A pair of telescoping screws delayed rearward movement of the operating parts during the firing cycle. This weapon was ultimately not selected for production. The screw-delayed action is similar to the Blish lock
Blish lock
The Blish Lock is a breech locking mechanism designed by John Bell Blish based upon his observation that under extreme pressures, certain dissimilar metals will resist movement with a force greater than normal friction laws would predict. In modern engineering terminology, it is considered to be an...
although Mannlicher's prototype pre-dates the Blish patent.
Floating chamber
David Marshall Williams (a noted designer for the U.S. Ordnance Office and later WinchesterWinchester Repeating Arms Company
The Winchester Repeating Arms Company was a prominent American maker of repeating firearms, located in New Haven, Connecticut. The Winchester brand is today used under license by two subsidiaries of the Herstal Group, Fabrique Nationale of Belgium and the Browning Arms Company of Morgan, Utah.-...
) developed a mechanism to allow firearms designed for full-sized cartridges to fire .22 caliber rimfire ammunition reliably. His system used a small 'piston' that incorporates the chamber. When the cartridge is fired, the front of the piston is thrust back with the cartridge giving a significant push to the bolt. Often described as accelerated blowback, this amplifies the otherwise anemic recoil energy of the .22 rimfire cartridge. Williams designed a training version of the Browning machine gun and the Colt Service Ace .22 long rifle version of the M1911
M1911
The M1911 is a single-action, semi-automatic, magazine-fed, and recoil-operated handgun chambered for the .45 ACP cartridge. John M. Browning designed the firearm which was the standard-issue side arm for the United States armed forces from 1911 to 1985. The M1911 is still carried by some U.S....
using his system. The floating chamber is both a blowback and gas operated mechanism.
Primer actuated
Primer actuated firearms utilize blowback force to set the primer back to operate a mechanism to unlock and cycle the firearm. John T. Kewish and John GarandJohn Garand
John Cantius Garand was a designer of firearms best known for creating the first successful semi-automatic rifle to be widely used in active military service, the M1 Garand....
were the first to develop the system in an unsuccessful bid to replace the M1903 bolt action rifle. (The U.S. military adopted ammunition with crimped primers that do not set back. Another Garand design was eventually accepted.) AAI Corporation used their developmental piston primer mechanism in a rifle submitted for the SPIW competition. A similar system is used in the spotting rifles on the LAW 80
LAW 80
The LAW 80 , sometimes erroneously referred to as LAW 94, is a man-portable, disposable anti-tank weapon currently in use by the British Army and a few other militaries.-Description:...
and Shoulder-launched Multipurpose Assault Weapon
Shoulder-Launched Multipurpose Assault Weapon
The Shoulder-Launched Multipurpose Assault Weapon is a shoulder-launched rocket weapon, based on the Israeli B-300, with the primary function of being a portable assault weapon and a secondary anti-armor rocket launcher. It was introduced to the United States armed forces in 1984...
use a 9mm, .308 Winchester
.308 Winchester
The .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...
based cartridge with a .22 Hornet
.22 Hornet
The .22 Hornet is a low-end vermin, small-game and predator centerfire rifle cartridge. It is considerably more powerful than the .22 WMR and the .17 HMR, achieving higher velocity with a bullet twice the weight. The Hornet also differs very significantly from these in that it is not a rimfire...
blank cartridge in place of the primer. Upon firing, the Hornet case sets back a short distance, unlocking the action.
Blish lock
The Blish Lock is a breech locking mechanism designed by John Bell Blish based upon his observation that under extreme pressures, certain dissimilar metals will resist movement with a force greater than normal friction laws would predict. In modern engineering terminology, it is called static friction, or stictionStiction
Stiction is the static friction that needs to be overcome to enable relative motion of stationary objects in contact. The term is a portmanteau of the term "static friction", perhaps also influenced by the verb "stick"....
. His locking mechanism was used in the Thompson submachine gun
Thompson submachine gun
The Thompson is an American submachine gun, invented by John T. Thompson in 1919, that became infamous during the Prohibition era. It was a common sight in the media of the time, being used by both law enforcement officers and criminals...
, Autorifle
Thompson Autorifle
The Thompson Autorifle was a semi-automatic rifle that used a Blish Lock to delay the action of the weapon. It was chambered in .30-06, with the 1923 model in 7.62mm Russian rifle rounds....
and Autocarbine
Thompson Light Rifle
The Thompson Light Rifle was an attempt by Auto-Ordnance to manufacture a light rifle for the US Armed Forces. The overall weapon was based on their well proven .45 ACP submachine gun...
designs. This dubious principle was later eliminated as redundant in the .45 caliber submachine gun. Any actual advantage could also be attained by adding a mere ounce of mass to the bolt.
Savage rotating barrel
The Savage system employed the theory that the rifling in the barrel caused a rotational force that would hold the gun locked until the projectile left the barrel. It was later discovered that the bullet had left the barrel long before any locking could occur. Savage pistols were in fact operating as pure blowback firearms.Other autoloading systems
Other autoloading systems are:- Blow forwardBlow forwardBlow-forward is a firearm operation where the barrel is virtually the only moving part of the weapon that is forced forward against a spring by the cartridge pressure and friction of the projectile against the rifling...
where the barrel is the only moving component of the weapon that is dragged forward by the friction of the bullet until it leaves the barrel. - Recoil operationRecoil operationRecoil operation is an operating mechanism used in locked-breech, autoloading firearms. As the name implies, these actions use the force of recoil to provide energy to cycle the action...
uses the rearward movement of parts of the weapon counter to the ejecta moving forward, as described by Newton's third law of motion. - GatlingGatling gunThe Gatling gun is one of the best known early rapid-fire weapons and a forerunner of the modern machine gun. It is well known for its use by the Union forces during the American Civil War in the 1860s, which was the first time it was employed in combat...
and other mechanical means utilize mechanical energy from an operator turning a crank. - ChainChain gunA chain gun is a type of machine gun or autocannon that uses an external source of power, rather than diverting energy from the cartridge, to cycle the weapon, and does so via a continuous loop of chain similar to that used on a motorcycle or bicycle. "Chain gun" is a registered trademark of...
and others utilize external power through electrical or hydraulic energy for operation. - Gas-operated reloadingGas-operated reloadingGas-operation is a system of operation used to provide energy to operate autoloading firearms. In gas-operation, a portion of high pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and chamber a new cartridge. Energy from the gas is harnessed...
External links
- Lever-delayed blowback
- Information about the TZ45 submachine gun and the concept of advanced primer ignition
- Blowback action, Animation and explanation at howstuffworks.com
- HKPro HKPro page explaining the principle, albeit using the "roller-locking" terminology
- Heckler and Koch USA now uses the "roller-delayed blowback" terminology
- Blow-Forward operated submachine gun patent
- Blow-Forward firearm patent
- Lever-Delayed Blowback AK
- Lever-Delayed Blowback AK
- Lever-Delayed Blowback AK
