An M40 recoilless rifle on its M79 "wheelbarrow" tripodDiagram of the operation of a recoilless rifle using a vented case
A recoilless rifle (rifled), recoilless launcher (smoothbore), or simply recoilless gun, sometimes abbreviated to "RR" or "RCL" (for ReCoilLess)[1] is a type of lightweight artillery system or man-portable launcher that is designed to eject some form of countermass such as propellant gas from the rear of the weapon at the moment of firing, creating forward thrust that counteracts most of the weapon's recoil. This allows for the elimination of much of the heavy and bulky recoil-counteracting equipment of a conventional cannon as well as a thinner-walled barrel, and thus the launch of a relatively large projectile from a platform that would not be capable of handling the weight or recoil of a conventional gun of the same size. Technically, only devices that use spin-stabilized projectiles fired from a rifled barrel are recoilless rifles, while smoothbore variants (which can be fin-stabilized or unstabilized) are recoilless guns. This distinction is often lost, and both are often called recoilless rifles.[2]
Though similar in appearance to a tube-based rocket launcher (since these also operate on a recoilless launch principle), the key difference is that recoilless weapons fire shells using a conventional smokeless propellant. While there are rocket-assisted rounds for recoilless weapons, they are still ejected from the barrel by the deflagration of a conventional propelling charge.
Because some projectile velocity is inevitably lost to the recoil compensation, recoilless rifles tend to have inferior range to traditional cannon, although with a far greater ease of transport, making them popular with paratroop, mountain warfare and special forces units, where portability is of particular concern, as well as with some light infantry and infantry fire support units. The greatly diminished recoil allows for devices that can be carried by individual infantrymen: heavier recoilless rifles are mounted on light tripods, wheeled light carriages, or small vehicles, and intended to be carried by crew of two to five. The largest versions retain enough bulk and recoil to be restricted to a towed mount or relatively heavy vehicle, but are still much lighter and more portable than cannon of the same scale. Such large systems have been replaced by guided anti-tank missiles in many armies.
The earliest known example of a design for a gun based on recoilless principles was created by Leonardo da Vinci in the 15th or early 16th century.[3] This design was of a gun which fired projectiles in opposite directions, but there is no evidence any physical firearm based on the design was constructed at the time.
In 1879, a French patent was filed by Alfred Krupp for a recoilless gun.[4]
The first recoilless gun known to have actually been constructed was developed by Commander Cleland Davis of the US Navy, just prior to World War I. His design, named the Davis gun, connected two guns back-to-back, with the backwards-facing gun loaded with lead balls and grease of the same weight as the shell in the other gun. His idea was used experimentally by the British as an anti-Zeppelin and anti-submarine weapon mounted on a Handley Page O/100bomber and intended to be installed on other aircraft.[5]
In the Soviet Union, the development of recoilless weapons ("Dinamo-Reaktivnaya Pushka" (DRP), roughly "dynamic reaction cannon") began in 1923. In the 1930s, many different types of weapons were built and tested with configurations ranging from 37 to 305mm (1.5 to 12.0in). Some of the smaller examples were tested in aircraft (Grigorovich I-Z and Tupolev I-12) and saw some limited production and service, but development was abandoned around 1938. The best-known of these early recoilless rifles was the Model 1935 76mm DRP designed by Leonid Kurchevsky. A small number of these mounted on trucks saw combat in the Winter War. Two were captured by the Finns and tested; one example was given to the Germans in 1940.
The first recoilless gun to enter service in Germany was the 7.5 cm Leichtgeschütz 40 ("light gun" '40), a simple 75mm smoothbore recoilless gun developed to give German airborne troops artillery and anti-tank support that could be parachuted into battle. The 7.5cm LG 40 was found to be so useful during the invasion of Crete that Krupp and Rheinmetall set to work creating more powerful versions, respectively the 10.5 cm Leichtgeschütz 40 and 10.5 cm Leichtgeschütz 42. These weapons were loosely copied by the US Army. The Luftwaffe also showed great interest in aircraft-mounted recoilless weapons to allow their planes to attack tanks, fortified structures and ships. These included the unusual Düsenkanone 88, an 88mm recoilless rifle fed by a 10-round rotary cylinder and with the exhaust vent angled upwards at 51 degrees to the barrel so it could pass through the host aircraft's fuselage rather than risking a rear-vented backblast damaging the tail, and the Sondergerät SG104 "Münchhausen", a gargantuan 14-inch (355.6mm) weapon designed to be mounted under the fuselage of a Dornier Do 217. None of these systems proceeded beyond the prototype stage.[6]
The US did have a development program, and it is not clear to what extent the German designs were copied. These weapons remained fairly rare during the war, although the American M20 became increasingly common in 1945. Postwar saw a great deal of interest in recoilless systems, as they potentially offered an effective replacement for the obsolete anti-tank rifle in infantry units.
During World War II, the Swedish military developed a shoulder-fired 20mm device, the Pansarvärnsgevär m/42 (20mm m/42); the British expressed their interest in it, but by that point the weapon, patterned after obsolete anti-tank rifles, was too weak to be effective against period tank armor. This system would form the basis of the much more successful Carl Gustav recoilless rifle postwar.
By the time of the Korean War, recoilless rifles were found throughout the US forces. The earliest American infantry recoilless rifles were the shoulder-fired 57mm M18 and the tripod-mounted 75mm M20, later followed by the 105mm M27: the latter proved unreliable, too heavy, and too hard to aim.[7] Newer models replacing these were the 90mm M67 and 106mm M40 (which was actually 105mm caliber, but designated otherwise to prevent accidental issue of incompatible M27 ammunition). In addition, the Davy Crockett, a muzzle-loaded recoilless launch system for tactical nuclear warheads intended to counteract Soviet tank units, was developed in the 1960s and deployed to American units in Germany.
The Soviet Union adopted a series of crew-served smoothbore recoilless guns in the 1950s and 1960s, specifically the 73mm SPG-9, 82mm B-10 and 107mm B-11. All are found quite commonly around the world in the inventories of former Soviet client states, where they are usually used as anti-tank guns.
The British, whose efforts were led by Charles Dennistoun Burney, inventor of the WallbusterHESH round, also developed recoilless designs. Burney demonstrated the technique with a recoilless 4-gauge shotgun. His "Burney Gun" was developed to fire the Wallbuster shell against the Atlantic Wall defences, but was not required in the D-Day landings of 1944. He went on to produce further designs, with two in particular created as anti-tank weapons. The Ordnance, RCL, 3.45 in could be fired off a man's shoulder or from a light tripod, and fired an 11lb (5kg) wallbuster shell to 1,000 yards. The larger Ordnance RCL. 3.7in fired a 22.2lb (10kg) wallbuster to 2,000yd (1.8km). Postwar work developed and deployed the BAT (Battalion, Anti Tank) series of recoilless rifles, culminating in the 120mm L6 WOMBAT. This was too large to be transported by infantry and was usually towed by jeep. The weapon was aimed via a spotting rifle, a modified Bren Gun on the MOBAT and an American M8C spotting rifle on the WOMBAT: the latter fired a .50 BAT (12.7x77mm) point-detonating incendiary tracer round whose trajectory matched that of the main weapon. When tracer rounds hits were observed, the main gun was fired.
During the late 1960s and early 1970s, SACLOSwire-guided missiles began to supplant recoilless rifles in the anti-tank role. While recoilless rifles retain several advantages such as being able to be employed at extremely close range, as a guided missile typically has a significant deadzone before it can arm and begin to seek its target, missile systems tend to be lighter and more accurate, and are better suited to deployment of hollow-charge warheads. The large crew-served recoilless rifle started to disappear from first-rate armed forces, except in areas such as the Arctic, where thermal batteries used to provide after-launch power to wire-guided missiles like M47 Dragon and BGM-71 TOW would fail due to extremely low temperatures. The former 6th Light Infantry Division in Alaska used the M67 in its special weapons platoons, as did the Ranger Battalions and the US Army's Berlin Brigade. The last major use was the M50 Ontos, which mounted six M40 rifles on a light (9 short tons (8.2t; 8.0 long tons)) tracked chassis. They were largely used in an anti-personnel role firing "beehive" flechette rounds. In 1970, the Ontos was removed from service and most were broken up. The M40, usually mounted on a jeep or technical, is still very common in conflict zones throughout the world, where it is used as a hard-hitting strike weapon in support of infantry, with the M40-armed technical fulfilling a similar combat role to an attack helicopter.
Front-line recoilless weapons in the armies of modern industrialized nations are mostly man-portable devices such as the Carl Gustav, an 84mm weapon. First introduced in 1948 and exported extensively since 1964, it is still in widespread use throughout the world today: a huge selection of special-purpose rounds are available for the system, and the current variant, known as the M4 or M3E1, is designed to be compatible with computerized optics and future "smart" ammunition. Many nations also use a weapon derived from the Carl Gustav, the one-shot AT4, which was originally developed in 1984 to fulfil an urgent requirement for an effective replacement for the M72 LAW after the failure of the FGR-17 Viper program the previous year. The ubiquitous RPG-7 is also technically a recoilless gun, since its rocket-powered projectile is launched using an explosive booster charge (even more so when firing the OG-7V anti-personnel round, which has no rocket motor), though it is usually not classified as one.
There are a number of principles under which a recoilless gun can operate, all involving the ejection of some kind of counter-mass from the rear of the gun tube to offset the force of the projectile being fired forward. The most basic method, and the first to be employed, is simply making a double-ended gun with a conventional sealed breech, which fires identical projectiles forwards and backwards. Such a system places enormous stress on its midpoint, is extremely cumbersome to reload, and has the highly undesirable effect of launching a projectile potentially just as deadly as the one launched at the enemy at a point behind the shooter where their allies may well be.
The most common system involves venting some portion of the weapon's propellant gas to the rear of the tube, in the same fashion as a rocket launcher. This creates a forward directed momentum which is nearly equal to the rearward momentum (recoil) imparted to the system by accelerating the projectile. The balance thus created does not leave much momentum to be imparted to the weapon's mounting or the gunner in the form of felt recoil. Since recoil has been mostly negated, a heavy and complex recoil damping mechanism is not necessary. Despite the name, it is rare for the forces to completely balance, and real-world recoilless rifles do recoil noticeably (with varying degrees of severity). Recoilless rifles will not function correctly if the venting system is damaged, blocked, or poorly maintained: in this state, the recoil-damping effect can be reduced or lost altogether, leading to dangerously powerful recoil. Conversely, if a projectile becomes lodged in the barrel for any reason, the entire weapon will be forced forward.
M40 Recoilless Rifle ammunition, showing the perforated casing
Recoilless rifle rounds for breech-loading reloadable systems resemble conventional cased ammunition, using a driving band to engage the rifled gun tube and spin-stabilize the projectile. The casing of a recoilless rifle round is often perforated to vent the propellant gases, which are then directed to the rear by an expansion chamber surrounding the weapon's breech. In the case of single-shot recoilless weapons such as the Panzerfaust or AT4, the device is externally almost identical in design to a single-shot rocket launcher: the key difference is that the launch tube is a gun that launches the projectile using a pre-loaded powder charge, not a hollow tube. Weapons of this type can either encase their projectile inside the disposable gun tube, or mount it on the muzzle: the latter allows the launching of an above-caliber projectile. Like single shot rocket launchers, the need to only survive a single firing means that single-shot recoilless weapons can be made from relatively flimsy and therefore very light materials, such as fiberglass. Recoilless gun launch systems are often used to provide the initial thrust for man-portable weapons firing rocket-powered projectiles: examples include the RPG-7, Panzerfaust 3 and MATADOR.
Since venting propellant gases to the rear can be dangerous in confined spaces, some recoilless guns use a combination of a countershot and captive piston propelling cartridge design to avoid both recoil and backblast. The Armbrust "cartridge," for example, contains the propellant charge inside a double-ended piston assembly, with the projectile in front, and an equal countermass of shredded plastic to the rear. On firing, the propellant expands rapidly, pushing the pistons outward. This pushes the projectile forwards towards the target and the countermass backwards providing the recoilless effect. The shredded plastic countermass is quickly slowed by air resistance and is harmless at a distance more than a few feet from the rear of the barrel. The two ends of the piston assembly are captured at the ends of the barrel, by which point the propellant gas has expanded and cooled enough that there is no threat of explosion. Other countermass materials that have been used include inert powders and liquids.
Obsolete 75mm M20 and 105mm M27 recoilless rifles were used by the U.S. National Park Service and the U.S. Forest Service as a system for triggering controlled avalanches at a safe distance, from the early 1950s until the US Military's inventory of surplus ammunition for these weapons was exhausted in the 1990s. They were then replaced with M40 106mm recoilless rifles, but following a catastrophic in-bore ammunition explosion that killed one of the five-man gun crew at Alpine Meadows Ski Resort, California, in 1995 and two further in-bore explosions at Mammoth Mountain, California, within thirteen days of each other in December 2002, all such guns were removed from use and replaced with surplus 105mm howitzers.[8]
A grenade launcher is a weapon that fires a specially designed, large-caliber projectile, often with an explosive, smoke, or gas warhead. Today, the term generally refers to a class of dedicated firearms firing unitary grenade cartridges. The most common type are man-portable, shoulder-fired weapons issued to individuals, although larger crew-served launchers are issued at higher levels of organization by military forces.
A mortar is usually a simple, lightweight, man-portable, muzzle-loaded weapon, consisting of a smooth-bore metal tube fixed to a base plate with a lightweight bipod mount and a sight. They launch explosive shells in high-arcing ballistic trajectories. Mortars are typically used as indirect fire weapons for close fire support with a variety of ammunition.
Shoulder-fired missile, shoulder-launched missile or man-portable missile, among other variants, are common slang-terms to describe high-caliber shoulder-mounted weapons systems – that is: weapons firing large heavy projectiles ("missiles"), typically using the backblast principle, which are small enough to be carried by a single person and fired while held on one's shoulder. The word "missile" in this context is used in its original broad sense of a heavy projectile, and encompasses all shells and rockets, guided or unguided. A more formal variant is simply shoulder-fired weapons system and the like.
An anti-tank rifle is an anti-materiel rifle designed to penetrate the armor of armored fighting vehicles, most commonly tanks, armored personnel carriers, and infantry fighting vehicles. The term is usually used for weapons that can be carried and used by one person, but is sometimes used for larger weapons. The usefulness of rifles for this purpose ran from the introduction of tanks in World War I until the Korean War. While medium and heavy tank armor became too thick to be penetrated by rigid projectiles from rifles that could be carried by a single soldier, anti-tank rifles continued to be used against other "soft" targets, though recoilless rifles and rocket-propelled grenades such as the bazooka were also introduced for infantry close-layer defense against tanks.
The Carl Gustaf 8.4 cm recoilless rifle is a Swedish developed 84 mm (3.3 in) caliber man-portable shoulder-fired recoilless rifle, initially developed by the Royal Swedish Army Materiel Administration during the second half of the 1940s as a close-range anti-tank and support weapon for infantry, which has seen great export success around the globe and is today a popular multi-purpose support weapon in use by many nations. The Carl Gustaf 84 mm recoilless rifle is a lightweight, low-cost weapon that uses a wide range of ammunition, which makes it extremely flexible and suitable for a wide variety of roles.
Caseless ammunition (CL), or caseless cartridge, is a configuration of weapon-cartridge that eliminates the cartridge case that typically holds the primer, propellant and projectile together as a unit. Instead, the propellant and primer are fitted to the projectile in another way so that a cartridge case is not needed, for example inside or outside the projectile depending on configuration.
The Steyr IWS 2000 is an Austrian single-shot bolt-action anti-materiel rifle produced by Steyr Mannlicher. IWS stands for Infantry Weapon System. Unlike other anti-tank rifle designs, it has a smoothbore barrel. This facilitates higher projectile velocities and allows a longer barrel service life, but the lack of gyroscopic spin-stabilization requires the projectile to have aerodynamic stabilizing fins instead. The IWS is chambered in a 15.2×169 mm armor-piercing fin-stabilized discarding-sabot cartridge, and is the first man-portable rifle to use this type of ammunition.
An anti-tank gun is a form of artillery designed to destroy tanks and other armoured fighting vehicles, normally from a static defensive position. The development of specialized anti-tank munitions and anti-tank guns was prompted by the appearance of tanks during World War I. To destroy hostile tanks, artillerymen often used field guns depressed to fire directly at their targets, but this practice expended too much valuable ammunition and was of increasingly limited effectiveness as tank armor became thicker. The first dedicated anti-tank artillery began appearing in the 1920s, and by World War II was a common appearance in many European armies. To penetrate armor, they fired specialized ammunition from longer barrels to achieve a higher muzzle velocity than field guns. Most anti-tank guns were developed in the 1930s as improvements in tanks were noted, and nearly every major arms manufacturer produced one type or another.
A tank gun is the main armament of a tank. Modern tank guns are high-velocity, large-caliber artilleries capable of firing kinetic energy penetrators, high-explosive anti-tank, and cannon-launched guided projectiles. Anti-aircraft guns can also be mounted to tanks.
The 3.45 inch RCL was an 88mm British recoilless weapon, designed by Sir Dennis Burney during the Second World War. Delayed by problems due to breach wear because of gas erosion upon firing, it did not see action, as was hoped, in the Far East, particularly Burma. However, it did lead to the post-war Mobat and Wombat recoilless rifles.
The M40 recoilless rifle is a portable, crew-served 105 mm recoilless rifle made in the United States. Intended primarily as an anti-tank weapon, it could also be employed in an antipersonnel role with the use of an antipersonnel-tracer flechette round. The bore was commonly described as being 106 mm caliber but is in fact 105 mm; the 106 mm designation was intended to prevent confusion with incompatible 105 mm ammunition from the failed M27. The air-cooled, breech-loaded, single-shot rifle fired fixed ammunition and was used primarily from a wheeled ground mount. It was designed for direct firing only, and sighting equipment for this purpose was furnished with each weapon, including an affixed spotting rifle.
The M20 recoilless rifle is a U.S. 75 mm caliber recoilless rifle T21E12 that was used during the last months of the Second World War and extensively during the Korean War. It could be fired from an M1917A1 .30 caliber machine gun tripod, or from a vehicle mount, typically a Jeep. Its shaped charge warhead, also known as HEAT, was capable of penetrating 100 mm of armor. Although the weapon proved ineffective against the T-34 tank during the Korean War and most other tanks, it was used primarily as a close infantry support weapon to engage all types of targets including infantry and lightly armored vehicles. The M20 proved useful against pillboxes and other types of field fortifications.
A spotting rifle or ranging gun is a small-calibre rifle used as a sighting device for artillery. The ballistics of the spotting rifle are matched to those of the artillery piece, so that if a shot from the spotting rifle lands on the target, it may be assumed that the main weapon will also do so.
The M18 recoilless rifle is a 57 mm shoulder-fired, anti-tank recoilless rifle that was used by the U.S. Army in World War II and the Korean War. Recoilless rifles are capable of firing artillery-type shells at reduced velocities comparable to those of standard cannon, but with greater accuracy than anti-tank weapons that used unguided rockets, and almost entirely without recoil. The M18 was a breech-loaded, single-shot, man-portable, crew-served weapon. It could be used in both anti-tank and anti-personnel roles. The weapon could be both shoulder fired or fired from a prone position. The T3 front grip doubled as an adjustable monopod and the two-piece padded T3 shoulder cradle could swing down and to the rear as a bipod for the gunner. The most stable firing position was from the tripod developed for the water-cooled Browning M1917 machine gun.
The high–low system is a design of cannon and anti-tank warfare launcher using a smaller high-pressure chamber to store propellant. It allows a much larger projectile to be launched without the heavy equipment usually needed for large caliber weapons. When the propellant is ignited, the higher pressure gases are bled out through vents at reduced pressure to a much larger low pressure chamber to push a projectile forward. The high-low system allows the weight of the weapon and its ammunition to be reduced significantly. Production cost and time are drastically lower than for standard cannon or other small-arm weapon systems firing a projectile of the same size and weight. It has a far more efficient use of the propellant, unlike earlier recoilless weapons, where most of the propellant is expended to the rear of the weapon to counter the recoil of the projectile being fired.
The AT4 is a Swedish 84 mm (3.31 in) unguided, man-portable, disposable, shoulder-fired recoilless anti-tank weapon manufactured by Saab Bofors Dynamics. The AT4 is not a rocket launcher strictly speaking, because the explosive warhead is not propelled by a rocket motor. Rather, it is a smooth-bore recoilless gun. Saab has had considerable sales success with the AT4, making it one of the most common light anti-tank weapons in the world. The M136 AT4 is a variant used by the United States Army.
Man-portable anti-tank systems are traditionally portable shoulder-launched projectile systems firing heavy shell-type projectiles, typically designed to combat protected targets, such as armoured vehicles, field fortifications and at times even low-flying aircraft.
The Carl Gustaf 20 mm recoilless rifle, service name 20 mm pansarvärnsgevär m/42, meaning "20 mm antitank rifle model 1942", was the first recoilless rifle produced by Carl Gustafs Stads Gevärsfaktori. The weapon had a penetration of just over 4 cm RHA with its standard solid shot armour piercing projectile and quickly became obsolete against modern armour, leading to the development of higher caliber recoilless guns, eventually resulting in the Carl Gustaf 84 mm recoilless rifle in 1948.
References
↑ "Recoilless Weapons"(PDF). Small Arms Survey Research Notes. Vol.55. December 2015. pp.1–4. Archived from the original(PDF) on 2016-03-14. Retrieved 2018-04-02.
↑ Julio, S. (April 1953), Las Armas Modernas de Infantería
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