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110-753: The Ballester–Molina was designed to offer the Argentine Federal Police and other armed forces a cheaper alternative to the "Sistema Colt Modelo 1927", itself a licensed copy of the Colt M1911A1 , built under the supervision of Colt engineers. Production of the Ballester–Molina began in 1938 and ceased in 1953. The Sistema Colt 1927 was manufactured until 1966, outliving its intended successor by more than two decades. The company's history dates back to 1929, when two Spanish entrepreneurs, Arturo Ballester and Eugenio Molina, established

220-421: A United States Army Materiel Command engineering course from 1970, "The advanced primer ignition gun is superior to the simple blowback because of its higher firing rate and lower recoil momentum. However, favorable performance depends on timing that must be precise. A slight delay in primer function, and the gun reverts to a simple blowback without the benefit of a massive bolt and stiffer driving spring to soften

330-591: A superintendente , a less common word in Spanish. Both superintendente and the much more common Spanish word comisario normally translate into English as superintendent, which creates some translation problems when discussing Argentine police services. Training for all serving agents of the service is done by the following institutions: Aside from its former stations in Buenos Aires, it maintains provincial stations in select capital cities and several towns of

440-635: A university specializing in criminology , is associated with Interpol , and participates in special forces training programs at the Los Angeles Police Department . In January 2017, most of the Federal Police agents serving in the city of Buenos Aires were transferred to a new local law enforcement agency, the Buenos Aires City Police . The new agency took over the local policing responsibilities in

550-419: A 1980s design by A.F. Barishev . The Mamontov and Goryainov rifles are only partially automatic; only the bolt unlocking is powered by the gases pushing the cartridge back, while the rest of the cycle (ejection, reloading) is done manually as in a traditional bolt-action rifle. A major problem with using the case cartridge as piston is that its motion is much faster (about 1 ms) compared to tapping gas further down

660-411: A 500-pound (230 kg) bolt to keep the cartridge safely in the barrel during the first few milliseconds. Yet the bolt must cycle far enough back to eject the spent casing and load a new round, which would limit the return spring to an average force of 60 pounds-force (270 N). The resulting system, if it could be built, would not have enough energy to cycle reliably or even keep the bolt closed when

770-505: 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. The case cartridge itself has been used experimentally to actuate the action similar to Garand's primer-actuation. Known prototypes using this method of operation include two 1936 rifle designs, one by Mihail Mamontov and another by Makar Goryainov at TsKB-14 , and

880-407: A barrel chamber with pressure relief ports that allow gas to leak into an annular chamber during extraction. Basically the opposite of a fluted chamber lubrication as it is intended for the cartridge to stick to the chamber wall making a slight delay of extraction. This requires a welded-on sleeve with an internal annular groove to contain the pressure. John Pedersen 's patented system incorporates

990-603: A branch of Hispano-Suiza in Buenos Aires , " Hispano-Argentina S.A. ". Years later, HAFDASA hired two engineers, Frenchman Rorice Rigaud and Carlos Ballester–Molina, a relative of the founders. Rigaud became the chief designer of the firm, while Ballester–Molina was appointed chief executive officer . As the Ballester–Molina was designed to serve alongside the Modelo 1927 that was currently in Argentine service, it bears

1100-418: A breech block independent of the slide or bolt carrier. When in battery, the breech block rests slightly forward of the locking shoulder located in the frame of the firearm. When the cartridge is fired, the cartridge case, bolt and slide move together a short distance until the breech block strikes the locking shoulder and stops. The slide continues rearward with the momentum it acquired in the initial phase while

1210-421: A chamber ring near the shoulder which is used to avoid bolt-bounce rather than a delay element. Similar operations exist using a fluted chamber for delay. When the round is fired, the cartridge sticks to the fluted chamber walls making a slight delay of extraction. The prototype 6x45mm SAW caliber Brunswick light machine gun is an example that used this operation. Another example using a ported chamber that uses

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1320-409: A chamber-ring delayed firearm, the chamber is conventional in every respect except for a concave ring within the chamber wall. When the cartridge is fired, the case expands into this recessed ring and pushes the bolt face rearward. As the case moves to the rear this ring constricts the expanded portion of the case. The energy required to squeeze the walls of the cartridge case slows the rearward travel of

1430-477: 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

1540-580: A feature of a wide range of designs that can be traced back to Becker's, including the Oerlikon cannon widely used as anti-aircraft weapons during World War II. To increase performance of API blowback firearms, larger calibre APIB guns such as the Becker and Oerlikon use extended chambers, longer than is necessary to contain the round, and ammunition for APIB firearms come with straight-sided cartridges with rebated rims (rims that are smaller in diameter than

1650-406: A gas piston. These omissions are conducive to relatively light construction by significantly reducing the number of parts required and the amount of machining required to produce a rifle. 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

1760-453: 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 KRISS Vector use modified versions of this concept. CMMG introduced the MkG carbine incorporating a radial-delay in 2017. This system uses

1870-538: A large bolt to handle the pressure of the round as well as a spring buffer shock absorbing butt plate on the stock to handle recoil. There were also a few rifles that chambered cartridges specifically designed for blowback operation. Examples include the Winchester Model 1905 , 1907 and 1910 . The only known assault rifle to use simple blowback was the Burton Model 1917. Although simple blowback

1980-450: A like-it-or-not basis led by Ott-Helmuth von Lossnitzer , the director of Mauser Werke's Weapons Research Institute and Weapons Development Group. Experiments showed roller-delayed blowback firearms exhibited bolt-bounce as the bolt opened at an extreme velocity of approximately 20 m/s (66 ft/s) during automatic fire. To counter bolt-bounce the perfect angle choice on the nose of the bolt head had to be found to significantly reduce

2090-462: A mechanical disadvantage, delaying 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. Leverage can be applied with a dedicated part or through inclined surfaces interacting with each other. This leverage significantly increases resistance and slows the movement of the lightweight bolt. The reliable functioning of lever-delayed blowback arms

2200-420: A mere ounce of mass to the bolt. 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 simple blow back firearms. The French MAB PA-15 and PA-8 9mm pistols feature

2310-469: A negative evaluation of Barishev's gun, pointing out that the main problems with reliability of firearms using the cartridge case as a piston were known since the 1930s and still unsolved. 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

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2420-462: A radial direction relative to the center of their bolt. The bearings engage corresponding pockets of the barrel extension when the bolt carrier group is in battery. The bearings are pushed outward due to spring pressure (e.g., a buffer spring) that compresses the carrier into the rear of the bolt. The carrier causes an internal component of the bolt carrier group named the lifter to push the bearings outward. The Lifter has angled grooves that interact with

2530-717: A second division was constituted in Rosario . In the next year the Buenos Aires group was formed. The unit was established under the denomination of Special Combat Teams in 1978, when Argentina hosted the Football World Cup . Ten years later, in 1988, the division changed its name to Police Operations Group and officially became the premier counter-terrorism team of the Federal Police . Officer Ranks (in descending order) Sub-Officer Ranks (in descending order) The Dirección General de Aviación Federal

2640-652: A striking resemblance to the Colt M1911A1. The Ballester–Molina and the M1911 share an identical seven-round magazine, barrel, recoil spring, and barrel bushing. Although many other parts appear identical at first glance, they are not; only the barrel and magazine are interchangeable. The Ballester–Molina is also known as HAFDASA , after the initials of its manufacturer. The Ballester–Molina was predominantly used by Argentina's security forces. The Argentine Army adopted it as its standard sidearm in 1938. The Ballester–Molina

2750-572: A toggle-lock delayed-blowback-operated rifle. Also in 1884, a few months after Maxim, a British patent for blowback-operated pistols and rifles was filed by Richard Paulson. In 1887 a patent was filed by an American inventor called Carl J. Bjerkness for a blowback-operated rifle. In 1888 a delayed-blowback machine gun known as the Skoda was invented by Grand Duke Karl Salvator and Colonel von Dormus of Austria. The blowback (sometimes referred to as "simple", "straight" or "pure" blowback) system represents

2860-475: Is a short recoil -operated semi-automatic locked breech pistol. The locking system is a near-identical copy of the Model 1911's, with the swinging lock used to unlock the barrel from the slide. The pistol has a two-stage, single action trigger, but unlike that of the 1911 trigger, it pivots rather than slide. The spring housing system is integrated to the pistol frame rather than being a separate part. The hammer

2970-400: 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 within this broad principle of operation, each distinguished by the methods used to control bolt movement. In most actions that use blowback operation,

3080-531: Is a unit of PFA agents, responsible for transportation policeman to anywhere in the country, besides the air support operations to the Federal Police. It has multipurpose aircraft for health functions, VIP transport, search, patrol, fire fighting, rescue and tactical operations. Its operational base is the heliport of Isla Demarchi (Heliport Dársena Sur). Its current fleet includes: Pistols Submachine guns Battle/Assault rifles Shotguns Machine guns Sniper rifles Blowback (arms) Blowback

3190-400: Is broken, allowing the propellant gas to be suddenly released in an explosive muzzle blast . The expanding gas also creates a jet propulsion effect rearward in the barrel against the spent cartridge case. This "blowback" is the predominant component of the recoil . Some guns use energy from blowback to perform the automatic bolt cycling /reloading process, while others will use a portion of

3300-613: Is called static friction, or stiction . His locking mechanism was used in the Thompson submachine gun , Autorifle and Autocarbine designs. This dubious principle was later eliminated as redundant in the M1 and M1A1 versions of the submachine guns at the insistence of the US Army. Lubrication or fouling would completely defeat any delay. Whatever actual advantage a clean, unlubricated Blish system could impart could also be attained by adding

3410-539: Is limited by specific ammunition and arm parameters like bullet weight, propellant charge, barrel length and amount of wear. John Pedersen patented one of the first known designs for a lever-delay system. The mechanism was also used by Hungarian arms designer Pál Király in the 1910s and 1930s and used in the Danuvia 39M and 43M submachine guns for the Hungarian Army . After World War II , Király settled in

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3520-439: Is limited to guns using low-power rounds, it is so efficient that in small-calibre semi-automatic pistols it has become almost ubiquitous. Heavier calibre semiautomatic handguns typically employ a short recoil system , of which by far the most common type are Browning -derived designs which rely on a locking barrel and slide assembly instead of blowback. But blowback guns can be used to fire powerful cartridges if they are of

3630-605: Is locked by the frame-mounted manual safety , and most notably there is no grip safety. Many examples for sale on the surplus market have seen heavy use but show little internal wear. About 8000 were sold to the United Kingdom during World War II . In a September 2007 article in the Argentine gun magazine Magnum , about the British-ordered Ballester–Molina pistols, gun writer and collector George E. Arbones' research and collection data seems to indicate

3740-483: Is purely academic. The important point is that it partakes some of the properties of both classes and, depending on the particular problem at hand, may be considered to be either one." In 1663 a mention is made in the journal of the Royal Society for that year of an engineer who came to Prince Rupert with an automatic weapon, though how it worked is unknown. In 1854 a hydropneumatically delayed-blowback cannon

3850-461: Is stripped from the magazine and chambered as the bolt returns to its in-battery position. The blowback system is practical for firearms using relatively low-power cartridges with lighter weight bullets. Higher power cartridges require heavier bolts to keep the breech from opening prematurely; at some point, the bolt becomes too heavy to be practical. For an extreme example, a 20 mm cannon using simple blowback and lubricated cartridges would need

3960-497: Is sufficient for the bullet to leave the muzzle and for the internal pressure in the barrel to decrease to a safe level. The bolt and cartridge are then pushed to the rear by the residual gas pressure. Because of high pressures, rifle-caliber delayed blowback firearms, such as the FAMAS , AA-52 and G3 , typically have fluted chambers to ease extraction. Below are various forms of delayed-blowback actions: Roller-delayed blowback

4070-539: Is the national civil police force of the Argentine federal government. The PFA has detachments throughout the country. Until January 1, 2017, it also acted as the local law enforcement agency in the capital, Buenos Aires . The history of this police force can be traced to 1580, when the founder of Buenos Aires, Captain Juan de Garay , established a local militia for defense against potential Native American raids. The Policía de Buenos Aires (Buenos Aires Police) operated for

4180-629: The .22 Long Rifle cartridge. Popular examples include the Marlin Model 60 and the Ruger 10/22 . Most blowback carbines and submachine guns are chambered for pistol cartridges such as the 9×19mm Parabellum, .40 S&W and .45 ACP. Examples include the MP 40 , Sten and UZI . The bolt can be made bigger and more massive in these weapons than in handguns, as they are intrinsically heavier and designed, ideally at least, to be fired with both hands, often with

4290-705: The 1994 reform of the Argentine Constitution , whose article 129 granted the City of Buenos Aires greater self-governance. This in principle included the transfer of control of the 25,000-strong Federal Police to the Jefe de Gobierno (elected Mayor), and the Buenos Aires City Legislature . Shortly before the historic, June 30, 1996, elections to these posts, however, a senior Peronist Senator , Antonio Cafiero , succeeded in limiting

4400-592: The British 8th Army and the SOE , and how he came to have his own British-marked Ballester–Molinas. Around 8000 Ballester–Molinas were specially manufactured for Britain during World War II . A number of pistols was issued to agents of the SOE, in order to avoid the use of British weapons for undercover operations in occupied Europe and behind enemy lines. This is very plausible due to the number of pistols of this contract found in

4510-902: The Dominican Republic and developed the Cristóbal Carbine (or Király-Cristóbal Carbine) employing a similar mechanism. Other weapons to use this system are the Hogue Avenger and Benelli B76 pistols, the FNAB-43 submachine gun, the TKB-517 , VAHAN and FAMAS assault rifles, the Sterling 7.62 and AVB-7.62 battle rifles/light machine guns , and the AA-52 general-purpose machine gun. Gas-delayed blowback should not be confused with gas-operation . In gas-delayed guns

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4620-540: The Grossfuss Sturmgewehr (with slightly more efficiency), and after the war by the Heckler & Koch P7 , Walther CCP , Steyr GB and M-77B pistols. 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

4730-468: The M1903 Springfield rifle. This operation is one of the most simple forms of delayed blowback but unless the ammunition is lubricated or uses a fluted chamber, the recoil can be volatile especially when using full length rifle rounds. Rotation of the bolt should be at least 90° to prevent ruptured cartridges. Another form of this operation using a helical screw to delay rearward movement was

4840-468: The MGD PM-9 uses this operation. 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

4950-606: The March 1976 coup , when the force participated in the abduction, torture and murder of thousands of dissidents and others. It was only with the 1983 presidential elections (and the return to democratic rule) that the FP began restoring its prestige and its relations with the Argentine people, especially with the 1986 appointment of Juan Angel Pirker as police commissioner general. The 1993 Olivos Pact between President Carlos Menem and his predecessor, UCR leader Raúl Alfonsín resulted in

5060-639: The Provinces of Argentina . The FFS also doubles as the state fire service as well. The GEOF is a specialized police unit of the General Directorate of International Terrorism and Complex Crimes. Although the existence of special forces in Argentina begins in 1930, the unit was officially created after the 1994 AMIA bombing . In 1994 its first section was established in Tucumán and in 1997

5170-539: 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 and also prevents synchronized fire through an aircraft propeller arc. According to

5280-539: The Salvator-Dormus M1893 machine gun and later the prototype Kalashnikov Model 1942 submachine gun in 1942 and the Fox Wasp carbine . David Marshall Williams (a noted designer for the U.S. Ordnance Office and later Winchester ) 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

5390-457: The UCR sought to bring about reforms to the undemocratic electoral system , led to the appointment of a conservative congressman, retired Col. Ramón Falcón , to the post of chief of police; Falcón's repressive tenure ended with his 1909 assassination. The current entity resulted from an initiative by the chief of police, Col. Emilio Ramírez, assisted by LTCOL Enrique Fentanes . A panel convened by

5500-467: The bolt 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 was used by some World War II German designs for the 7.92×33mm Kurz cartridge, including the Volkssturmgewehr rifle (with little effectiveness) and

5610-415: 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, delay 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. The blowback principle may be considered a simplified form of gas operation , since

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5720-414: The headspace and hence the correct positioning of the cartridges in the (closed) chamber. Due to usage wear the bolt gap between the locking piece and bolt head carrier is expected to gradually increase. It can be determined and checked by a feeler gauge measurement and can be altered by changing the cylindrical rollers for rollers with a different diameter. Installing larger diameter rollers will increase

5830-399: The rotation of the bolt head to accelerate the bolt carrier of an AR-15 pattern rifle. The bolt locking lugs are adapted to incorporate 120° angles that rotate the bolt as it travels rearward under conventional blowback power. As the bolt rotates 22.5˚, it must accelerate the bolt carrier to the rear through an adapted 50° angle cam-pin slot. This acceleration amplifies the effective mass of

5940-630: 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 increased recoil produced by the floating chamber made these training guns behave more like their full-power counterparts while still using inexpensive low-power ammunition. The floating chamber is both a blowback and gas operated mechanism. Primer actuated firearms use

6050-596: The Mannlicher Model 1893 automatic rifle, the bolt in screw-delayed blowback uses a turn bolt that was delayed by angled interrupted threads delayed by a quarter twist to unlock. John T. Thompson designed an autorifle 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

6160-550: The PFA, when the calculating populist had Alberto Villar named as chief at the behest of adviser José López Rega . Villar was a member of López Rega's newly organized paramilitary group, the Argentine Anticommunist Alliance , and Villar's participation in spiraling violence between the group and those on the far left led to his assassination in 1974. The institution's prestige was further damaged following

6270-612: The StG 45 (M), had not progressed beyond the prototype stage by the end of World War II. After World War II, former Mauser engineers Ludwig Vorgrimler and Theodor Löffler perfected the mechanism between 1946 and 1950 while working for the French small arms manufacturer Centre d'Etudes et d'Armament de Mulhouse (CEAM). In 1950 Ludwig Vorgrimler was recruited to work for CETME in Spain. The first full-scale production rifle to utilize roller-delay

6380-464: The aid of a shoulder stock; and these factors help to ameliorate the disruption to the shooter's aim caused by the heavy bolt's movement. Consequently, simple blowback is adequate for somewhat more powerful rounds in submachine guns than in standard pistols. One of the very few known simple blowback firearms capable of firing fully powered rifle cartridges was the Brixia 930 light machine gun, that required

6490-507: The alternative to API is some system of delayed or retarded blowback, in which the bolt is never fully locked, but is initially held in place, sealing the cartridge in the chamber by the mechanical resistance of one of various designs of delaying mechanism. As with the resistance provided by momentum in API, it takes a fraction of a second for the propellant gases to overcome this and start moving cartridge and bolt backwards; this very brief delay

6600-413: The arm to various propellant and projectile specific pressure behavior. Their reliable functioning is limited by specific ammunition and arm parameters like bullet weight, propellant charge, barrel length and amount of wear. At the moment of cartridge ignition the chamber has to be and remain sealed, until the bullet has exited the barrel and the gas pressure within the bore has dropped to a safe level before

6710-415: The barrel and pressures have dropped to a safe level. This mechanism was used on the Pedersen rifle and Schwarzlose MG M.07/12 machine gun. John Browning developed this simple method whereby the axis of bolt movement was not in line with that of the bore probably during late WWI and patented it in 1921. The result was that a small rearward movement of the bolt in relation to the bore-axis required

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6820-400: The bearings. Bearing delay is designed to be tuned based on the user's preference or configuration of other components by swapping to a lifter with a different geometry. The bearing delay design is described in U.S. patent 11,371,789 , U.S. patent 11,543,195 , U.S. patent 11,781,824 , and U.S. patent 12,146,717 . Lever-delayed blowback utilizes leverage to put the bolt at

6930-411: The blowback to operate only 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 gas pressure in

7040-660: The bolt carrier does not rebound. Due to the relative low bolt thrust exhibited by pistol cartridges the anti-bounce mechanism is omitted by Heckler & Koch on their roller-delayed blowback firearms chambered for pistols cartridges. Heckler & Koch's MP5 submachine gun is the most common weapon still in service worldwide using this system. The Heckler & Koch P9 semi-automatic pistol, CETME Ameli light machine gun, SIG MG 710-3 , Heckler & Koch HK21 and Ohio Ordnance REAPR general-purpose machine guns also use it. Roller-delayed blowback arms are ammunition specific, since they lack an adjustable gas port or valve to adjust

7150-420: The bolt carrier, slowing the speed of the bolt head. This delay allows pressure to drop prior to extraction without the penalty of a heavier bolt carrier assembly. The system is similar to roller and lever-delayed blowback in that it uses the mass of the bolt carrier moving at a faster rate than the bolt head to delay the action from opening. The design is described in U.S. patent 10,436,530 . First used on

7260-480: The bolt gap and push the locking piece forward. Installing smaller diameter rollers results in the reverse effects. Bearing delay blowback uses a plurality of ball bearings to delay the movement of the bolt carrier group after firing. MEAN introduced Bearing delay blowback in 2023 with their Bearing Delay Upper Receiver chambered in 9×19mm Parabellum. This system uses the movement of three ball bearings arranged approximately 120° apart from one another that move in

7370-429: The bolt head. The primary advantage of roller-delayed blowback is the simplicity of the design compared to gas or recoil operation. The roller-delayed blowback firearm action was patented by Mauser's Wilhelm Stähle and Ludwig Vorgrimler . Though appearing simple, its development during World War II was a hard technical and personal effort, as German engineering, mathematical and other scientists had to work together on

7480-426: The bolt-bounce problem. With these angles the geometrical transmission ratio of the bolt carrier to the bolthead became 3:1, so the rear bolt carrier was forced to move 3 times faster than the bolthead. The rearward forces on the bolt carrier and receiver were 2:1. The force and impulse transmitted to the receiver increases with the force and impulse transmitted to the bolt carrier. Making the bolt carrier heavier lessens

7590-482: 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. Advanced primer ignition (API) was originally developed by Reinhold Becker for use on the Becker Type M2 20 mm cannon . It became

7700-482: The bore through a piston—about 5 ms in the Dragunov sniper rifle , which used the same cartridge as Mamontov's rifle. Barishev made a fully automatic, but rather bulky mechanism that used a mechanical delay. In his system, the case cartridge pushed back a tilting bolt face, that upon reaching a certain angle pushes backwards an unlocking lever that continues farther before unlocking the bolt. The GRAU however still gave

7810-457: The breech remains locked. This allows chamber pressure to drop to safe levels once the bullet departs the barrel. The continuing motion of the slide lifts the breech block from its recess and pulls it rearward, continuing the firing cycle. Straight-walled cartridges are used in this operation as they are less prone to rupturing than tapered (conical) cartridges in firearms with bolt operations that instantly retract rounds when under high pressure from

7920-891: The capital city. The PFA is subordinate to the Ministry of Security . The organization is headed by the Chief of the PFA, the Comisario General Juan Carlos Hernández, assisted by the Deputy Chief of the PFA, Comisario General Osvaldo Mato. The PFA's headquarters, known as the Departamento Central de Policía , is located at 1650 Moreno Street, in the Montserrat section of Buenos Aires. The over 12,000 m (128,000 ft²) resulted from an 1868 proposal for its construction, which

8030-408: The cartridge case behaves like a piston driven by the powder gases. Other operating principles for self-loading firearms include delayed blowback , blow forward , gas operation , and recoil operation . In firearms, a blowback system is generally defined as an operating system in which energy to operate the firearm's various mechanisms, and automate the loading of another cartridge, is derived from

8140-439: The cartridge itself). 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 the 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

8250-743: The case and slide, reducing their mass requirements. The first known use of the system was on the Fritz Mann pistol in 1920 and later on the High Standard Corp model T3 experimental pistol developed by Ott-Helmuth von Lossnitzer while working for High Standard. Other firearms that used this system were the LWS Seecamp pistol, the AMT Automag II, and the Kimball .30 Carbine pistol. The SIG SG 510 rifle family incorporates

8360-404: The chamber when firing. The Pedersen Remington Model 51 pistol, SIG MKMO submachine gun and R51 pistol are the only production firearms to have used this design. Flywheel delayed blowback operation is where, during firing, the bolt opening is delayed by the rotational inertia of a flywheel. This is driven by a rack and pinion arrangement on the bolt carrier. The Barnitzke , Kazachok SMG, and

8470-435: The chamber, will undergo a degree of blowback action. The energy from the expansion of gases upon 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. How

8580-399: The chamber. When the cartridge is fired, the front of the floating chamber is thrust back by gas pressure impinging on the front of the chamber as in a traditional piston. This, added to the blowback energy imparted on the cartridge, pushes the bolt back with greater energy than either force alone. Often described as "accelerated blowback", this amplifies the otherwise anemic recoil energy of

8690-437: The city's autonomy by advancing National Law 24.588, which reserved control of the force, among other faculties, to the national government . The controversial bill, signed in 1996 by President Menem, remained a sticking point between successive Presidents (most of whom have been Peronist) and Buenos Aires Mayors (none of whom have been). A 2005 agreement on principles between Mayor Aníbal Ibarra and President Néstor Kirchner

8800-477: The energy of primer setback to unlock and cycle the firearm. John Garand developed the system in an unsuccessful bid to replace the M1903 bolt-action rifle in the early 1920s. Garand's prototypes worked well with US military .30-06 ammunition and uncrimped primers, but then the military changed from a fast burning gunpowder to a progressive burning Improved Military Rifle (IMR) powder. The slower pressure rise made

8910-636: The first three hundred years up to 1880, when the Federalization of Buenos Aires resulted in the creation of the Policía de la Capital (Police of the Capital). Incidents of social unrest in subsequent years helped prompt the Fraga Law in 1904, which provided for the inclusion of neighborhood representatives as commissioners in their respective precincts. The failed Revolution of 1905 , by which

9020-423: The force required to compress the action spring. The design must ensure that the delay is long enough that the bullet exits the barrel before the cartridge case clears the chamber. The empty case is ejected as the bolt travels to the rear. The stored energy of the compressed action spring then drives the bolt forward (although not until the trigger is pulled if the weapon fires from an open bolt ). A new cartridge

9130-400: The front outer surface of the cartridge case and its interior and thus ensures extraction without tearing the case making extraction easier and more reliable. In 1944 other German companies like Großfuß (de) , Rheinmetall and C.G. Haenel showed interest in developing roller-delayed blowback small arms. Großfuß worked on a roller-delayed blowback MG 45 general-purpose machine gun that, like

9240-417: The gas pressure slightly longer until it reaches a safe level to extract. This operation is almost similar to a simple blowback operation, API blowback firearms that have fired the round at the point where the cartridge is fully chambered operate in a similar way. For more powerful rounds that cannot be safely used in simple blowback, or in order to obtain a lighter mechanism than the simple format can provide,

9350-545: The gun is tilted up. Due to the required bolt weight, blowback designs in pistols are generally limited to calibers smaller than 9×19mm Parabellum (e.g., .25 ACP , .32 ACP , .380 ACP , 9×18mm Makarov , etc.) There are exceptions such as the simple blowback pistols from Hi-Point Firearms which include models chambered in .40 S&W and .45 ACP . Simple blowback operation can also be found in small-bore (such as .22LR ) semi-automatic rifles , carbines and submachine guns . Most simple blowback rifles are chambered for

9460-550: The gun, resulting in a new MG FF/M model with ammunition not being interchangeable between the two models. The 30 mm MK 108 cannon was perhaps the apogee of API blowback technology during World War II. The principle is also used in some automatic grenade launchers, for example in the US Mk 19 grenade launcher or Russian AGS-30 . A closed bolt firing equivalent of Advanced Primer Ignition that uses straight-sided rebated rim cartridges in an extended deeper chambering to contain

9570-401: The inertia of the spent cartridge case being pushed out the rear of the chamber by rapidly expanding gases produced by a burning propellant, typically gunpowder. When a projectile (e.g. bullet ) is still within the gun barrel , the high-pressure propellant gas behind it is contained within what could be seen as a closed system ; but at the moment it exits the muzzle , this functional seal

9680-426: The larger sense, blowback might well be considered a special form of gas operation. This is reasonable because the cartridge case may be conceived of as a sort of piston driven by the powder gases. Actually, blowback involves so many special problems that it is best considered to be in a class by itself. The question whether or not it should be included within the more general class of gas operation or recoil operation

9790-622: The legend British-bought Ballester–Molinas being manufactured using steel salvaged from the German pocket battleship Admiral Graf Spee after she was scuttled in the River Plate in Montevideo harbor, Uruguay. Another specialist, Alejandro Gherovici, dismissed the legend saying the steel was likely supplied by the US under Lend-Lease . Arbones' article also details the use of those pistols by

9900-427: The most basic auto loading operation type. In a blowback mechanism, the bolt rests against the rear of the barrel, but is not locked in place. At the point of ignition, expanding gases push the bullet forward through the barrel while at the same time pushing the case rearward against the bolt. The expanding gases push the bolt assembly to the rear, but the motion is slowed by the mass of the bolt, internal friction, and

10010-405: The movement of the bolt is controlled is 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" (often just "blowback"), "delayed/retarded blowback", and "advanced primer ignition". Relating blowback to other types of automatic firearm operation, George M. Chinn wrote that: "In

10120-584: The national executive increasingly made the force a political instrument during the country's often authoritarian regimes. General Juan Carlos Onganía , president after a 1966 coup, named a Federal Police director, Luis Margaride, who shared his distaste for modern culture, resulting in crusades against nightclubs, long hair, and miniskirts. Facing a government policy backdrop such as this, numerous avant-garde artists (and others, particularly in academia ) left Argentina, many never to return. The return of exiled President Juan Perón in 1973 resulted in conflict with

10230-410: The opening velocity of the bolt. The extremely high bolt carrier velocities problem was not solved by trial and error. Mathematician Karl Maier provided analysis of the components and assemblies in the development project. In December 1943 Maier came up with an equation that engineers used to change the angles in the receiver to 45° and 27° on the locking piece relative to the longitudinal axis reducing

10340-415: The other two types: API or delayed blowback. In the API blowback design, the primer is ignited when the bolt is still moving forward and before the cartridge is fully chambered (akin to the fire- out-of-battery principle used in some mountain guns like Canon de 65 M (montagne) modele 1906 , although there the bolt is locked and whole ordnance is moving at fire). This requires a very careful design to ensure

10450-465: The police chief presented its findings to support the establishment of the Federal Police on November 8, 1943, and on December 24, Decree 17.750 was signed by President Pedro Pablo Ramírez (the father of the chief of police). The new force did not immediately replace the Capital Police, but was instead transferred duties under the latter's purview incrementally. The first important such transfer

10560-675: The primer actuated prototypes unreliable, so Garand abandoned the design for a gas operated rifle that became the M1 Garand . AAI Corporation used a primer piston in a rifle submitted for the SPIW competition. Other rifles to use this system were the Postnikov APT and Clarke carbine as described in U.S. patent 2,401,616 . A similar system is used in the spotting rifles on the LAW 80 and Shoulder-launched Multipurpose Assault Weapon use

10670-404: The proper balance and equalization of forces between the projectile weight, propellant charge, barrel length, bolt weight, and return spring strength. In a simple blowback design, the propellant gases have to overcome static inertia to accelerate the bolt rearwards to open the breech. In an API blowback, they first have to do the work of overcoming forward momentum to arrest the forward motion of

10780-459: The recoil impact. [...] The exacting requirements in design and construction of gun and ammunition reduce this type almost to the point of academic interest only." API mechanisms are very sensitive to the ammunition used. For example, when the Germans switched their MG FF (an Oerlikon FFF derivative) to their new, lighter mine shell , they had to rebalance the spring strength and bolt weight of

10890-416: The recoil velocity. For Mausers StG 45(M) project Maier assumed a 120 g (4.2 oz) bolt head and 360 g (12.7 oz) bolt carrier (1 to 3 ratio). The prototype StG 45 (M) assault rifle had 18 longitudinal gas relief flutes cut in the chamber wall to assist the bloated cartridge casing from the chamber walls during extraction. Fluting the end of the chamber provides pressure equalization between

11000-557: The right side of the frame in addition to the manufacturer's serial number in the left side of the grip, under the slide and the last three numbers of the serial number marked on the barrel link tab. British Contract B125 displaying HAFDASA Serial Number 9019 is preserved at the Imperial War Museum in Leeds, UK. A version of the Ballester–Molina chambered for .22 Long Rifle was manufactured for training purposes. This version

11110-436: The seal is broken and chamber starts to open. For obtaining a proper and safe functioning parameters bandwidth arms manufactures offer a variety of locking pieces with different mass and shoulder angles and cylindrical rollers with different diameters. The angles are critical and determine the unlock timing and gas pressure drop management as the locking piece acts in unison with the bolt head carrier. The bolt gap width determines

11220-623: The second hand market in France. In 2002 the publication nº150 of the Magnum Magazine written by Santiago P. Tavella Madariaga provides data on this topic. Manufacture of the British Contract Ballester Molina pistol started most likely in 1941 with deliveries ending in 1944. British contract Ballester–Molinas are identified by serial numbers ranging from 8900 to 22.000, marked with a "B" prefix ( i.e. B1633 ) on

11330-414: The use of more powerful ammunition in a lighter gun than would be achieved by using simple blowback, and the reduction of felt recoil results in further weight savings. The original Becker cannon, firing 20×70mmRB ammunition, was developed to be carried by World War I aircraft, and weighed only 30 kg. Oerlikon even produced an anti-tank rifle firing 20×110mmRB ammunition using the API blowback operation,

11440-659: Was first used in Mauser 's Gerät 06H prototype. Roller-delayed blowback operation differs from roller-locked recoil operation as seen in the MG 42 and gas operated roller locked, as seen in the Gerät 03 and Gerät 06 . Unlike the MG 42, in roller-delayed blowback the barrel is fixed and does not recoil, and unlike the Gerät 03 and Gerät 06 and StG 44, roller-delayed blowback systems lack

11550-489: Was followed by the modification of the especially contentious article 7, which denied the city its own, local police force, in 2007 - though the "Cafiero Law" otherwise remains in force. Efforts since 2007 by Mayor Mauricio Macri to declare it unconstitutional have thus far failed, and though the Mayor inaugurated a Metropolitan Police, issues of revenue sharing for its financing remain pending. The PFA, since 1974, maintains

11660-614: Was identical externally to the standard Ballester–Molina, except for slide markings indicating the caliber. However, the .22 caliber version is blowback operated to accommodate the less-powerful rimfire cartridge. This version was produced in much smaller numbers and is much rarer today. The Ballester–Molina pistol also came with an extended barrel and a wooden buttstock. Argentine Federal Police 34°36′47″S 58°23′17″W  /  34.61306°S 58.38806°W  / -34.61306; -58.38806 The Argentine Federal Police ( Spanish : Policía Federal Argentina or PFA )

11770-568: Was patented by Henry Bessemer . In 1856 a crank-operated cannon with a blowback-operated cocking mechanism was patented in the US by Charles E. Barnes. In 1876 a single-shot breech-loading rifle with an automatic breech-opening and cocking mechanism using a form of blowback was patented in Britain and America by the American Bernard Fasoldt. In 1883 Hiram Maxim patented a blowback-operated rifle. In 1884 he would also patent

11880-598: Was the February 7, 1944, assignment as the Presidential Guard of the Casa Rosada , and on March 10, the process of unifying the two forces was initiated by decree, concluding officially on January 1, 1945. The Federal Police changed slowly in its organizational structure in subsequent decades. Initially maintaining 45 precincts, it added five in 1946, two in 1976, and a 53rd in 1999. Its subordinate role to

11990-732: Was the Spanish CETME battle rifle , which was closely followed by the Swiss SIG SG 510 and the CETME Model B-based Heckler & Koch G3 . The G3 bolt features an anti-bounce mechanism that prevents the bolt from bouncing off the barrel's breech surface. The G3's "bolt head locking lever" is a spring-loaded claw mounted on the bolt carrier that grabs the bolt head as the bolt carrier group goes into battery. The lever essentially ratchets into place with friction, providing enough resistance to being re-opened that

12100-445: Was ultimately approved in 1884. Designed by Juan Antonio Buschiazzo , and engineered by Francesco Tamburini , the ornate headquarters is an eclectic structure with influences from Baroque architecture , and features a number of patios , notably the central, Palm Tree Patio. Argentine Passports were issued to local residents at this location until 1996. The organization of the PFA is as follows: Superintendencies are commanded by

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