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An M40 recoilless rifle on its M79 "wheelbarrow" tripod
Diagram of the operation of a recoilless rifle using a vented case

A recoilless rifle (rifled), recoilless launcher (smoothbore), recoilless rocket launcher,[1] or simply recoilless gun, sometimes abbreviated to "rr" or "RCL" (for ReCoilLess)[2] 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.[3]

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 Such large systems have been replaced by guided anti-tank missiles in many armies.

History

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Jonga, mounted with 105 mm RCL gun which destroyed most of the tanks during the 1971 Indo-Pakistani war
1.57-inch Davis recoilless gun mounted in the nose of an F5L flying boat, with a parallel Lewis machine gun. Photo circa 1918.

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.[4] 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.[5]

The first recoilless gun known to have 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/100 bomber and intended to be installed on other aircraft.[6]

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 305 mm (1.5 to 12.0 in). 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 76 mm 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 75 mm smoothbore recoilless gun developed to give German airborne troops artillery and anti-tank support that could be parachuted into battle. The 7.5 cm 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 88 mm 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 (355.6 mm) weapon designed to be mounted under the fuselage of a Dornier Do 217. None of these systems proceeded beyond the prototype stage.[7]

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 (this was not the case for the US where no anti-tank rifle was adopted on a large scale).

During World War II, the Swedish military developed a shoulder-fired 20 mm device, the Pansarvärnsgevär m/42 (20 mm 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.

M67 recoilless rifle

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 57 mm M18 and the tripod-mounted 75 mm M20, later followed by the 105 mm M27: the latter proved unreliable, too heavy, and too hard to aim.[8] Newer models replacing these were the 90 mm M67 and 106 mm M40 (which was actually 105 mm 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 73 mm SPG-9, 82 mm B-10 and 107 mm 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.

Polish soldiers operating an SPG-9M in the 1970s

The British, whose efforts were led by Charles Dennistoun Burney, inventor of the Wallbuster HESH 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 11 lb (5 kg) wallbuster shell to 1,000 yards. The larger Ordnance RCL. 3.7in fired a 22.2 lb (10 kg) wallbuster to 2,000 yd (1.8 km). Postwar work developed and deployed the BAT (Battalion, Anti Tank) series of recoilless rifles, culminating in the 120 mm 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, SACLOS wire-guided missiles began to supplant recoilless rifles in the anti-tank role. While recoilless rifles and their ammunition retain several advantages such as being cheaper and easier to produce and maintain, as well 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 (8.2 t; 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.

Front-line recoilless weapons in the armies of modern industrialized nations are mostly man-portable devices such as the Carl Gustav, an 84 mm 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.

Design

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Firing of a Carl Gustaf 8.4cm recoilless rifle, showing the propellant gas backblast

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.

Civilian use

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United States Forest Service team using a 105 mm M27 Recoilless Rifle for avalanche control at Mammoth Mountain in the Inyo National Forest in 1981.

Obsolete 75 mm M20 and 105 mm 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 U.S. military's inventory of surplus ammunition for these weapons was exhausted in the 1990s. They were then replaced with M40 106 mm 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 105 mm howitzers.[9]

See also

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References

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Recoilless rifle

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from Grokipedia
A recoilless rifle is a lightweight, direct-fire weapon that eliminates by venting a portion of the gases rearward through a or venturi at the breech end, thereby counteracting the forward of the . This principle of operation allows the weapon to be man-portable or vehicle-mounted without requiring heavy mitigation structures, enabling units to employ larger-caliber rounds for anti-tank, anti-fortification, or general support roles. Typically operated by one or two personnel, recoilless rifles bridge the gap between and conventional , offering high-velocity projectiles with effective ranges up to several kilometers while maintaining mobility. The origins of the recoilless rifle trace back to early 20th-century innovations aimed at reducing in constrained platforms, such as aircraft. In 1911, U.S. Navy Cleland Davis applied for a for a recoilless designed to overcome the severe forces of mounted on early airplanes, marking one of the first practical applications of the concept. Development accelerated during , when the need for portable anti-tank weapons prompted rapid prototyping across major powers; the U.S. Army adopted the 57mm in 1944 as a shoulder-fired system firing (HEAT) rounds at velocities around 1,200 feet per second. Postwar advancements refined the technology, leading to models like the 75mm M20 and 106mm M40, which incorporated improved nozzles for better gas ejection efficiency and were widely used in the Korean and Wars for their versatility against armored vehicles and bunkers. In modern military applications, recoilless rifles remain relevant due to their adaptability and low logistical footprint, often serving as multi-role systems capable of firing high-explosive, anti-armor, or illumination rounds. The Swedish Carl-Gustaf M4, introduced in the , exemplifies contemporary design with its 84mm , reusable launcher, and compatibility with programmable munitions, allowing dismounted soldiers to engage targets at ranges exceeding 1,000 meters. Despite advantages in portability and firepower, recoilless rifles produce significant backblast hazards, requiring open space for safe firing, and their unguided nature limits precision compared to missile systems. Ongoing evolutions focus on integrating smart fuzes and reduced backblast features to enhance survivability in urban and confined environments.

History

Early inventions

The concept of a recoilless firearm emerged in the late 19th century amid efforts to develop lightweight artillery that could operate without heavy recoil-mitigating structures, particularly for naval and aerial applications. An early concept appeared in a 1879 French patent filed by Alfred Krupp for a recoilless gun, though not constructed. In the United States, pre-World War I experiments focused on mounting guns on early aircraft, where traditional recoil would destabilize flight. Commander Cleland Davis of the U.S. Navy addressed this challenge by inventing the Davis gun in 1911, the first recoilless weapon to be constructed and tested. This design employed a dual-barrel system in which a main forward-firing projectile was balanced by a simultaneous rearward discharge of a lighter blank cartridge or shot, effectively canceling recoil through opposing momentum. The gun received U.S. patents in 1914 and was intended for use on seaplanes for anti-submarine and anti-aircraft roles, allowing for lighter mounting systems without bulky recoil absorbers. Initial prototypes of the , including 30-pounder and 6-pounder variants, underwent testing at the Naval in , starting in October 1912. These early models demonstrated effective recoil neutralization, enabling stable firing from airborne platforms, but faced practical limitations such as the need for synchronized firing mechanisms and the reduced effectiveness of the rearward blank in varying conditions. British trials during further highlighted issues with reliability, including occasional misfires and the complexity of reloading in flight, leading to limited despite its innovative approach. In , parallel pre-war efforts explored lightweight anti-aircraft weapons to counter emerging aerial threats, though specific recoilless prototypes remained conceptual until wartime pressures accelerated development. These attempts emphasized portability for and mobile units, foreshadowing broader in later conflicts. By the mid-1910s, the Davis gun's counter-projectile principle influenced further experimentation, but challenges like incomplete balancing in prototypes contributed to high failure rates in sustained testing. German engineers, inspired by similar lightweight needs, pursued analogous designs for anti-aircraft roles, though documentation of pre-1918 prototypes is sparse and often tied to broader innovations rather than fully realized recoilless systems.

adoption

The accelerated the development of recoilless rifles during to provide with lightweight anti-tank capabilities superior to the in range and projectile power. The 57 mm , initiated as freelance engineering research in 1943, entered limited production by late 1944 after rapid testing and refinement, with over 2,000 units ordered by early 1945 alongside hundreds of thousands of rounds. Designed as a shoulder-fired or tripod-mounted weapon weighing about 47 pounds, the M18 was integrated into U.S. battalions as a crew-served , replacing heavier towed in mobile operations and allowing squads to engage armored targets at effective ranges up to 500 yards (maximum range of 4,000 yards). Concurrently, the 75 mm was developed in parallel starting in 1943, achieving operational status by March 1945 with a weight of around 114 pounds; it was assigned to units for support, emphasizing its role in providing high-explosive and anti-personnel effects without the need for large-caliber management systems. Britain introduced the PIAT (Projector, Infantry, Anti-Tank) in 1943 as a man-portable anti-tank weapon, a spigot mortar using a spring-loaded to achieve low without propellant gas venting. First deployed with Commonwealth forces during the in late 1942–early 1943, the PIAT saw extensive use in against Axis armor, proving effective at close ranges up to 100 yards despite its 37-pound weight and manual cocking mechanism. By mid-1943, it was standard issue for British infantry in and the Italian campaign, and later in Northwest Europe following the in 1944, where its ability to fire from enclosed positions without significant backblast enhanced urban combat utility. Approximately 115,000 units were produced by war's end, underscoring its tactical value in suppressing bunkers and light vehicles. Germany fielded the 7.5 cm Leichtgeschütz 40 (Le.G. 40) as its primary recoilless rifle starting in , a 75 mm weapon weighing 140 pounds that was towed or man-portable for support. Approximately 650 units were produced, with deployment in and for anti-tank roles, where its 3,280-yard range allowed adjustments not feasible with rigid rocket launchers. Larger variants like the 10.5 cm Leichtgeschütz 43 followed in 1943, but production remained limited to a few dozen due to resource constraints; these were used in defensive positions rather than naval applications. No widespread adoption of recoilless systems occurred, though experimental ship-mounted adaptations were considered for but not fielded at scale. Soviet efforts focused on early recoilless concepts from the 1920s and 1930s, such as the 76 mm DRP Model 1935, but wartime priorities emphasized mass-produced anti-tank rifles and guns over recoilless designs, resulting in no standardized infantry models by 1945. Prototypes like vehicle-mounted 37 mm and 45 mm systems were tested but abandoned due to reliability issues in extreme conditions. Japanese developments included adaptations of the Type 97 20 mm automatic cannon, a gas-operated anti-tank weapon introduced in 1937 that weighed 52 pounds and fired armor-piercing rounds at 750 m/s, but it was not truly recoilless and suffered severe recoil, limiting crew effectiveness. In humid Pacific environments, the Type 97's ammunition and mechanisms prone to corrosion reduced operational readiness, confining its use to defensive roles in China and early island campaigns before being overshadowed by lighter alternatives. Recoilless rifles offered key tactical advantages in II's confined battles, enabling to employ heavier calibers from portable platforms without heavy mounts, ideal for urban assaults where traditional risked structural collapse. In , their light weight facilitated rapid deployment through dense terrain, providing against fortifications without exposing crews to recoil-induced instability on uneven ground. In late-war European operations, U.S. forces leveraged recoilless rifles to neutralize German armor in close-quarters fighting, contributing to breakthroughs by allowing safe firing from foxholes and buildings despite backblast hazards. These weapons shifted tactics toward squad-level , reducing reliance on vulnerable towed guns in fluid fronts.

Post-war evolution and modern use

Following , the development of recoilless rifles advanced significantly, with the Swedish Carl Gustaf 8.4 cm series emerging as a cornerstone. Initiated in 1946 by the Swedish arms manufacturer Gevärsfaktori (later part of Saab), the original M1 model built on wartime concepts to create a man-portable, multi-role weapon capable of firing , and illumination rounds. Subsequent iterations, including the in 1964 for improved durability and the M3 in the 1980s for reduced weight, evolved into the lightweight M4 variant introduced in the 2010s, which incorporates programmable ammunition for enhanced precision. In the United States, the M67 90 mm recoilless rifle was adopted in the early for infantry anti-tank roles, seeing extensive use during the for its simplicity and effectiveness against bunkers and light armor. By the late , U.S. Army Rangers began transitioning to the Carl Gustaf M3 as a lighter alternative, with the upgraded M3E1 variant—featuring a body reducing weight by about 6 pounds—entering service for Forces around 2014 to provide greater versatility in urban and confined environments. This shift reflected broader Cold War-era refinements, where recoilless rifles proliferated through , such as India's adoption of the Carl Gustaf system in 1976 for its armed forces, enabling local manufacturing and integration into non-NATO inventories. Recoilless rifles maintained relevance in post-Cold War conflicts despite competition from guided missiles, which offered superior range and accuracy starting in the , leading to reduced demand for unguided systems in many Western militaries. In the War (2001–2021), U.S. and allied forces employed the Carl Gustaf for bunker-busting operations, valuing its reloadable design for sustained fire in mountainous terrain. Similarly, in the ongoing Russia- conflict since 2022, Ukraine received over 100 Carl Gustaf M2 units as part of international aid, using them alongside systems like the for anti-tank engagements against Russian armor. Proliferation continued to non-NATO nations, though guided missile advancements—such as the and TOW—challenged recoilless rifles' dominance by minimizing exposure risks for operators. Modern enhancements have revitalized recoilless rifles for 21st-century warfare, addressing key limitations like backblast hazards and guidance. The Carl Gustaf M4, for instance, features a softer-launch mechanism that reduces backblast danger, allowing safer use in enclosed spaces, while 2020s developments include laser-guided rounds like the (GMM) that extend effective range to over 1,000 meters without altering the weapon's compatibility with legacy ammunition. These upgrades, including programmable fuzes for airburst effects, ensure recoilless systems remain cost-effective for infantry against evolving threats like drones and fortified positions.

Operating principles

Recoil cancellation physics

The recoilless rifle achieves recoil cancellation through the application of Newton's third law of motion, which states that the forward force propelling the generates an equal and opposite reaction force. In conventional firearms, this reaction manifests as imparted to the weapon itself, but recoilless designs redirect the reaction by expelling propellant gases rearward with precisely balanced . This balances the system's forces without transmitting significant net impulse to the rifle, enabling lightweight construction suitable for portable use. The underlying principle is the conservation of linear for an , where the total before firing is zero and remains zero afterward. The forward of the is thus counteracted by the rearward of the expelled gases, expressed by the equation: mpvp+mgvg=0m_p v_p + m_g v_g = 0 Here, mpm_p is the projectile mass, vpv_p its (positive forward), mgm_g the mass of the expelled gases, and vgv_g the rearward velocity of the gases (negative). To derive this from the impulse- theorem, consider that the generates an impulse J=∫F dtJ = \int F \, dt on the , changing its from zero to mpvpm_p v_p. In a , this impulse would equally accelerate the rearward, but the open breech vents the gases, transferring the counter-impulse to them instead, resulting in near-zero net change for the when mgvg=−mpvpm_g v_g = -m_p v_p. The rearward gas velocity vgv_g is enhanced by a venturi-shaped nozzle at the breech, which constricts the flow path to accelerate the gases via the —reducing pressure and increasing speed as the gases pass through the narrow throat before expanding. This design ensures the lighter gas mass achieves the high velocity needed to match the projectile's , with optimized geometry and burn characteristics enabling effective momentum transfer. In contrast to traditional recoiling systems, where the recoil force F=ΔpΔtF = \frac{\Delta p}{\Delta t} (change in over firing time) must be absorbed by the or mount, recoilless rifles eliminate this force on the launcher by equalizing forward and rearward impulses over the same timeframe, permitting shoulder-fired operation without heavy recoil mitigation hardware. Early prototypes often failed due to practical limitations in balancing, as seen in the of 1911, where backblast hazards from rearward counter-projectiles resulted in residual risks and unreliable performance during trials.

Gas dynamics and backblast effects

In recoilless rifles, the propellant gases generated upon firing undergo rapid high-pressure expansion through the open breech and rear , initiating a supersonic flow with Mach numbers exceeding 1 that produces a hazardous rearward plume of hot, high-velocity exhaust. This flow is facilitated by convergent-divergent designs, which accelerate the gases to supersonic speeds to efficiently vent them rearward, creating a that propagates outward from the at the onset of venting. The supersonic nature of this expansion results in a highly directional and energetic plume, capable of causing severe burns, injuries, and debris projection in the immediate vicinity behind the weapon. The backblast forms a characteristic cone-shaped danger zone, typically spanning a 90-degree arc from the rear of the and extending 20-50 meters, within which overpressures can reach up to 30-40 psi close to the nozzle—levels sufficient to cause lethal injuries such as eardrum rupture, damage, or traumatic within 5 meters. This zone's intensity diminishes with distance but remains hazardous due to the plume's thermal and , which can ignite vegetation, damage equipment, or injure unprotected personnel even at the outer limits. The underlying momentum conservation principle ensures that the rearward gas ejection counters the projectile's forward motion, but the resulting backblast's scale directly correlates with the weapon's and propellant charge. To mitigate these hazards, crew positioning protocols require a clear , with assistants positioned at least 15-20 meters to the side and no personnel or obstacles within the cone to prevent reflection or deflection of the blast. Deflector screens or blast attenuators, such as perforated plates or venturi extensions, have been standardized in firing doctrines since the 1950s to redirect or diffuse the plume, reducing overpressure by up to 50% in tested configurations. These measures, first incorporated into U.S. recoilless rifle training manuals in the early era, emphasize pre-fire announcements like "backblast clear" to ensure safety during operations. Environmental factors, particularly wind, can deflect the backblast plume unpredictably, potentially directing hazards toward friendly forces and increasing risks of or secondary injuries; this was notably problematic in dense jungle environments during engagements with weapons like the , where gusts exacerbated plume dispersion and contributed to operational accidents. Efficiency trade-offs arise from optimizing gas velocity: higher velocities enhance recoil cancellation by requiring less vented mass for balance, but they intensify backblast hazards through greater plume energy and wider dispersion angles.

Design and components

Barrel and mounting systems

The barrel of a recoilless rifle is engineered with thin-walled construction using high-strength materials to reduce weight while withstanding the internal pressures and thermal stresses of firing. Common materials include steel liners, often overwrapped with composite jackets for enhanced durability and lightness; for example, the Carl Gustaf M4 employs a thin steel liner reinforced by a carbon fiber epoxy matrix. Barrel lengths are optimized for portability and ballistic efficiency, typically spanning 10 to 20 calibers in man-portable designs. The Carl Gustaf M3 measures 1.1 meters overall for its 84 mm bore, equating to about 13 calibers, while the M67 90 mm model extends 1.346 meters, roughly 15 calibers. At the rear, a venturi facilitates recoil cancellation by channeling gases rearward, with designs featuring conical or Laval profiles to accelerate and expand the gases efficiently. In the Carl Gustaf series, the venturi adopts a hinged conical shape integrated into the breech, allowing breech access while directing gas flow to counter momentum and manage backblast. The throat is generally sized near the bore diameter for optimal pressure balance, flaring outward to achieve supersonic gas velocities without excessive material stress. Mounting systems emphasize mobility for use, incorporating lightweight supports like bipods, , and shoulder stocks. The M67 90 mm recoilless rifle, for instance, uses a front and rear bipod for prone ground firing, supplemented by a and padded shoulder stock for unsupported shoulder shots, folding the bipod as a handle. Heavier variants, such as the M40 106 mm, rely on tripods for stability or mounts on vehicles like jeeps, adapting the same barrel to non-portable roles. Weight considerations drive design toward man-portable configurations, with unloaded masses of 5 to 15 kg to support individual carry or integration onto light platforms. The Carl Gustaf M4 achieves approximately 7 kg through its composite-overlaid barrel, permitting single-soldier transport and attachment to light trucks or door mounts. The M67, at 17 kg including sights, remains feasible for two-person teams while enabling mounting on lightweight vehicles. Barrel durability is constrained by exposure to high-velocity hot gases, causing progressive that degrades accuracy and . Service life typically spans several hundred rounds, after which barrels require replacement; for the M67, this is assessed via post-firing checks for velocity drop and dispersion widening. involves bore swabbing after every 10 rounds to remove residue and periodic inspections for , often using replaceable nozzle vents to extend tube usability before full barrel overhaul.

Ammunition types and loading mechanisms

Recoilless rifles utilize specialized ammunition tailored to their open-breech design, which vents propellant gases rearward to counter recoil. High-explosive anti-tank (HEAT) rounds form the core of anti-armor capabilities, employing shaped charge warheads that focus explosive energy into a high-velocity jet capable of penetrating 300-800 mm of rolled homogeneous armor (RHA), depending on the specific variant and target conditions. These projectiles are fin-stabilized for flight stability, with representative examples like the 84 mm FFV551 for the Carl Gustav system achieving penetration up to 400 mm RHA at a muzzle velocity of 255 m/s and an effective range of 700 m. Tandem-warhead variants, such as the FFV751, enhance performance against reactive armor, penetrating over 500 mm RHA at ranges up to 500 m. Beyond anti-tank roles, recoilless rifle includes high-explosive (HE), illumination, and rounds, which provide support and battlefield effects. These munitions operate at lower muzzle velocities of 200-300 m/s, reflecting the low-pressure propulsion necessary for effective cancellation without compromising the weapon's lightweight structure. For instance, HE rounds like the 84 mm HE 441 deliver fragmentation and blast effects for personnel targets, while illumination rounds deploy flares for night operations up to 2,000 m altitude, and rounds generate obscuring screens for cover or marking. Such versatility stems from the modular cartridge design, where warheads are interchangeable within the fixed casing. Loading mechanisms emphasize rapid cycling to support sustained engagement, typically involving breech-loading via a hinged block or sliding tray that opens the rear of the barrel for cartridge insertion. This allows a trained two-person to reload in approximately 10-15 seconds, far quicker than muzzle-loading alternatives, while ensuring the venturi nozzle remains unobstructed for gas escape. Fixed-round cartridges integrate the , , and casing into a single unit, simplifying handling and reducing misfires. Propellant systems in these fixed rounds rely on black powder for early designs or nitrocellulose-based smokeless powders in modern iterations, producing chamber pressures of 5,000-10,000 psi to propel the forward while directing an equal rearward gas impulse for neutralization. This controlled low-pressure regime—exemplified by 6,500 psi in developmental 57 systems—minimizes barrel stress and enables the use of lightweight materials. compatibility ensures safe gas venting through the open breech, preventing during firing. Modern advancements include guided munitions, such as the Saab/ (GMM) for the Carl Gustav, which incorporates to achieve effective ranges exceeding 1,000 m with programmable warheads for anti-armor, anti-personnel, or wall-breaching effects. Although 1980s developments like the FFV551 focused on unguided rocket-assisted trajectories, subsequent integrations of semi-active homing have enhanced precision without altering the core loading and propellant principles.

Military applications

Infantry and light artillery roles

Recoilless rifles have been integrated into squads as versatile crew-served weapons, typically operated by two-man teams consisting of a gunner and a loader, to deliver support against enemy positions and personnel. Systems like the 84mm Carl Gustaf, adopted by the U.S. Army as the M3/M4, enable squads to engage soft targets at effective ranges up to 1,000 meters for high-explosive rounds, enhancing maneuverability in close-quarters combat without the need for heavier crew-served systems. This squad-level employment allows for rapid deployment and repositioning, providing that complements and machine guns during assaults. In light artillery roles, recoilless rifles have served as battalion-level assets, offering indirect and direct suppression of enemy positions in lieu of more cumbersome howitzers. During and the , weapons such as the 75mm M20 provided mobile for advances, while the 105mm M27 recoilless rifle, introduced in the early , was employed to bombard fortified hills and bunkers without requiring extensive logistical support. In the , the 106mm fulfilled similar functions at the battalion level, delivering high-explosive rounds to neutralize enemy strongpoints and troop concentrations in dense terrain, often towed or man-portable for quick setup. The portability of recoilless rifle designs has proven particularly advantageous in rough terrain, facilitating deployment by airborne and marine units during operations like the Korean War's hill assaults, where lightweight systems could be manhandled up steep slopes to provide overhead fire. U.S. Army training doctrines, as outlined in FM 3-06.11 Combined Arms Operations in Urban Terrain, emphasize the use of recoilless rifles such as the Carl Gustaf for tasks including urban breaching, where crews are trained to employ high-explosive rounds to create entry points in walls and structures while minimizing exposure to return fire. Despite their effectiveness, recoilless rifles face limitations due to their reloadable but single-shot-per-round mechanism, which sustains practical rates of fire of 1 to 6 rounds per minute depending on the model and crew configuration, demanding frequent resupply during prolonged engagements.

Anti-tank and vehicle-mounted variants

Recoilless rifles have been specialized for anti-tank roles through the use of (HEAT) warheads, which employ mechanics to focus energy into a high-velocity jet capable of penetrating armored vehicles. The 106mm , introduced in the , exemplifies early adaptations, with its standard HEAT round achieving penetration of over 400mm of rolled homogeneous armor (RHA), sufficient against contemporary armor. In modern variants, such as the Saab Carl-Gustaf M4's HEAT 751 tandem warhead, the design incorporates a precursor charge to defeat (ERA) on tanks, followed by a main charge penetrating up to 500mm of RHA behind the ERA layer. These warheads briefly reference types optimized for armor defeat, prioritizing jet formation stability over . Vehicle-mounted variants enhance mobility and firepower for anti-tank operations, integrating recoilless rifles onto light platforms like jeeps or tracked vehicles. The , a U.S. Marine Corps deployed in the , mounted six 106mm M40 recoilless rifles in a traversable turret, allowing rapid salvos against armored targets while maintaining air-transportable weight under 10 tons. This configuration provided suppressive anti-tank capability in close support roles, though reloading required exposure outside the vehicle. Similar integrations on Humvees or jeeps extended the weapon's reach in units. Post-World War II evolution saw recoilless rifles adapt to multi-role anti-tank applications, including hybrid designs blending direct-fire precision with indirect support. During the 1973 Yom Kippur War, the Israel Defense Forces employed jeep-mounted 106mm recoilless rifles, locally manufactured variants of the M40, for tank hunting on dynamic fronts like the Golan Heights, where they complemented towed anti-tank guns in infantry brigades. These systems offered versatile fire support against Syrian T-55 and T-62 tanks, evolving from pure anti-armor tools to integrated brigade assets. In contemporary conflicts, recoilless rifles maintain anti-tank relevance through integration with unmanned aerial vehicles (UAVs) for target spotting, extending engagement beyond line-of-sight. Since 2022 in the , and continuing as of 2025, Ukrainian forces have paired systems like the Soviet-era 73mm recoilless rifle with FPV drones for reconnaissance and precision strikes on Russian armor, enabling adjustments for terrain-obscured targets up to 1,300 meters. Despite these advantages, vehicle-mounted and man-portable recoilless rifles exhibit drawbacks, particularly vulnerability to counterfire from their prominent backblast signature, which reveals firing positions through visible exhaust and . The backblast creates a hazardous zone up to 20 meters rearward, capable of causing severe injuries or fatalities to nearby personnel, as documented in training and combat incidents with weapons like the Carl-Gustaf. In urban ambushes during the (2003-2011), this signature contributed to elevated casualty risks for operators, with insurgents exploiting the telltale plume to direct return fire on exposed teams.

Civilian and non-military uses

Sporting and recreational applications

Recoilless rifles are classified as destructive devices under the (NFA) in the United States, requiring federal registration, a $200 tax stamp, and a thorough for civilian ownership. Ownership is permitted in states that allow NFA items. In sporting and recreational contexts, deactivated or modified recoilless rifles appear in historical reenactments, where groups simulate and scenarios using inert or low-power variants for authenticity. Organizations focused on historical firearms demonstrations occasionally adapt these weapons for educational events, emphasizing their portability for field setups. Availability of WWII-era surplus models, often deactivated for display, is limited to collectors' markets and auctions, with prices ranging from $5,000 to $20,000 in the 2020s depending on condition and functionality. Safety considerations for recreational use include employing reduced-charge ammunition to lessen backblast hazards, ensuring compliance with ATF regulations for destructive devices. Globally, civilian possession is heavily restricted; the prohibits such weapons for private individuals under Directive 2021/555, which bans category A firearms including destructive devices since the revisions.

Law enforcement and training purposes

Recoilless rifles have found limited application in contexts, primarily in specialized units where their anti-material capabilities support tactical operations. In training purposes, recoilless rifles are replicated through inert and laser-guided simulators to familiarize operators with handling, sighting, and backblast safety protocols without expending live . These trainers, modeled after systems like the Carl Gustav, are utilized to enhance proficiency in joint military- simulations. Non-lethal ammunition adaptations for recoilless rifles remain rare in police operations. Regulatory frameworks in the United States govern recoilless rifle acquisition for through the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), classifying them as destructive devices under the , requiring federal approval and registration, in contrast to prohibitive civilian ownership without special licensing. Adoption remains constrained by high costs, exceeding $10,000 per unit for systems like the Carl Gustav M4, coupled with a post-2010 shift toward dedicated less-lethal alternatives such as 40mm launchers and conducted energy devices for routine policing. In non-military contexts, demilitarized recoilless rifles have been used in and displays, such as modified versions for in movies, provided they comply with federal regulations like ATF approval for non-functional replicas.

References

  1. https://www.globalsecurity.org/military/world/artillery-rcl.htm
  2. https://armamentresearch.com/recoilless-weapons-in-confined-spaces/
  3. https://www.history.navy.mil/content/history/museums/nnam/explore/exhibits/permanent-exhibits/south-wing/davis-recoilless-gun.html
  4. https://www.lonesentry.com/manuals/recoilless-weapons/index.html
  5. https://www.saab.com/products/carl-gustaf-m4
  6. https://www.smallarmssurvey.org/sites/default/files/resources/SAS-Research-Note-55.pdf
  7. https://www.usni.org/magazines/naval-history-magazine/2018/april/armaments-innovation-davis-gun
  8. https://www.usni.org/magazines/naval-history-magazine/1989/april/technical-report-davis-gun-u-s-navy-first
  9. https://www.thearmorylife.com/history-of-recoilless-rifles/
  10. https://smallarmsreview.com/the-57mm-recoilless-rifle-from-both-sides-of-the-fence/
  11. https://www.tanks-encyclopedia.com/ww2/g/the-projector-infantry-anti-tank-p-i-a-t/
  12. http://ww2f.com/threads/recoilless-rifle-in-wwii.15059/
  13. https://www.militaryfactory.com/smallarms/detail.php?smallarms_id=241
  14. https://taskandpurpose.com/military-life/history-carl-gustaf-modern-warfare/
  15. https://newatlas.com/carl-gustav-recoilless-rifle-60-years/11503/
  16. https://combatoperators.com/weapons/anti-tank/carl-gustaf-m4/
  17. https://www.19fortyfive.com/2024/12/the-carl-gustaf-84mm-recoilless-rifle-is-the-real-deal-bazooka/
  18. https://taskandpurpose.com/news/army-m3e1-carl-gustaf-bazooka/
  19. https://www.saab.com/markets/india/stories/2024/three-things-to-know-about-saabs-carl-gustaf-manufacturing-facility-in-india
  20. https://www.twz.com/15629/the-army-rushes-a-1000-recoilless-rifles-to-troops-but-whats-a-carl-gustaf-anyway
  21. https://www.popularmechanics.com/military/weapons/a39281936/weapons-europe-is-sending-to-ukraine/
  22. https://www.popularmechanics.com/military/weapons/a23708392/army-recoilless-rifle-carl-gustav-laser-guided-warheads/
  23. https://www.twz.com/30786/guided-rounds-will-turn-the-beloved-carl-gustaf-recoilless-rifle-into-a-precision-weapon
  24. https://apps.dtic.mil/sti/tr/pdf/ADA023513.pdf
  25. https://patents.google.com/patent/US3026775A/en
  26. https://apps.dtic.mil/sti/tr/pdf/AD0785704.pdf
  27. https://arc.aiaa.org/doi/pdfplus/10.2514/6.2007-5160
  28. https://apps.dtic.mil/sti/tr/pdf/ADA149426.pdf
  29. https://www.globalsecurity.org/military/library/policy/army/fm/23-25/FM232_9.htm
  30. https://www.thearmorylife.com/m50-ontos/
  31. https://sadefensejournal.com/innovative-nammos-new-m72-ffe-an-achievement-in-perfect-countermass-balance/
  32. https://www.globalsecurity.org/military/world/europe/carl-gustaf.htm
  33. https://www.nzdf.mil.nz/nzdf/our-equipment/firepower/carl-gustaf-m3/
  34. https://weaponsystems.net/system/1569-90mm%2BM67%2BRecoilless%2BRifle
  35. https://odin.tradoc.army.mil/WEG/Asset/03fcd69335b928c4346b5ffc7219bffc
  36. https://www.globalsecurity.org/military/library/policy/army/fm/23-11/Ch2.htm
  37. https://apps.dtic.mil/sti/tr/pdf/ADA131239.pdf
  38. https://www.globalsecurity.org/military/world/europe/carl-gustaf-specs.htm
  39. https://strathconas.ca/carl-gustav-medium-range-anti-armour-weapon
  40. https://www.20thcenturyplatoons.com/articles/CarlGustaf1973.html
  41. https://www.army.mil/article/72402/carl_gustaf_weapon_extends_soldiers_lethal_reach
  42. https://www.army.mil/article/286735/light_infantry_lethality_understanding_the_power_of_the_goose
  43. https://www.globalsecurity.org/military/systems/ground/m27rclr.htm
  44. http://www.avalanchepress.com/CounterAttackUSMC.php
  45. https://www.globalsecurity.org/military/library/policy/army/fm/3-06-11/ch7.htm
  46. https://www.globalsecurity.org/military/systems/ground/m40rclr.htm
  47. https://www.saab.com/globalassets/event/aeroindia/84-mm-heat-751.pdf
  48. http://kampfgruppewillow.blogspot.com/2021/06/israeli-idf-artillery-and-at-guns-1973.html
  49. https://www.uasvision.com/2023/04/26/drones-help-ukraine-do-more-damage/
  50. https://pmc.ncbi.nlm.nih.gov/articles/PMC7578127/
  51. https://www.atf.gov/firearms/docs/guide/atf-national-firearms-act-handbook-atf-p-53208/download
  52. https://collectorssource.ca/product/us-m20-75mm-recoilless-rifle/
  53. https://www.atf.gov/firearms/qa/which-firearms-are-regulated-under-nfa
  54. https://home-affairs.ec.europa.eu/policies/internal-security/organised-crime/trafficking-firearms/eu-legislation-civilian-firearms_en
  55. https://thedefensepost.com/2024/03/06/saab-carl-gustaf-poland/
  56. https://www.twz.com/the-carl-gustaf-recoilless-rifle-confiscated-by-tsa-was-all-legal
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