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M67

Anti-tank recoilless rifle

M67 recoilless rifle

The M67 was short-lived in front-line service during the Cold War, but has returned from the armories to fight once again

 
 
Country of origin United States
Entered service 1963
Caliber 90 mm
Cartridge weight 3.08 or 4.2 kg
Weight (unloaded) 17 kg
Weight (loaded) 21.2 kg
Length (stock extended) 1.35 m
Muzzle velocity 213 m/s (318 m/s for M590 anti-personnel cartridge)
Sighting range 800 m
Range of effective fire (against stationary tank) 300 m
Range of effective fire (against moving tank) 200 m
Armor penetration 350 mm
Concrete penetration 800 mm
Packed sand penetration 1 100 mm

 

   The M67 is a US man-portable recoilless rifle first fielded in the early 1960s. Though it was officially retired from US service in 1975, it has been returned to active service by the on many occasions, and remains in the US inventory even now in 2019. The M67 has also been referred to as the MAW (Medium Anti-tank Weapon).

   The origins of the M67 are rooted in a late 1940s evaluation of the personal anti-tank weapons then operational in the US Army, which found the existing weapons wanting against current and near-future armored threats. It was determined that a 90 mm recoilless rifle was needed for the job, with a weight of 30 lbs (13.6 kg), an effective range of 500 yds (457 m), and a fin-stabilized projectile capable of penetrating 6 inches (152 mm) of steel armor at a 60 degree obliquity. This finding was made into a formal requirement for such a weapon, dubbed "PAT" (Platoon Anti-Tank), with a contract awarded to Arthur D. Little, Inc. to develop it. The resulting Arthur D. Little design was finalized by 1951, and was designated T149 by the Army.

   The US Army soon after decided it was prudent to fund a competing design as well, in order to widen their options. This contract went to the Midwest Research Institute (MRI) in December of 1951, whose resulting design was designated as the T184. The program soon changed radically however, due to a major restructuring of the PAT program by the Army's Office of the Chief of Ordnance that also changed the weapon's specifications. This also inverted the hierarchy of the two designs, as the T184 was easily changed to conform to the requirement (it was still in the design phase, while prototypes of the T149 had already been completed), and ammunition had not yet been produced for live fire testing of the T149. Thus, the T184 became the preferred design overnight, while the T149 had become the "backup" design.

   While the T184's design was found to meet or exceed all requirements, this was ironically its own undoing --- the Army's zeal for a 90 mm man-portable recoilless rifle that was as light and compact as possible had been poorly thought-out from the beginning, and live fire tests soon proved that the T184 was "too light to fight". Specifically, MRI had reduced the weight to 25 lbs (11.3 kg), but they also had to weaken the projectile's payload and ballistics to compensate, and the recoil had *still* proven too strong. Changes were made to the ammunition to compensate further (notably by incorporating rocket assistance into the projectiles; a measure which foreshadowed ammunition design trends in the SAAB-Bofors Carl Gustaf and AT-4 recoilless rifles), but the resulting projectiles had insufficient firepower to meet the PAT requirement.

   The requirements were changed to allow for a 30 lb (13.6 kg) weapon, and the T184 was redesigned into the much sturdier T219. This improved weapon also added a strengthened chamber, allowing for the use of the heavier and more powerful ammunition that Arthur D. Little had designed for the T149. Further refinement of the design produced the T219E1, which was finally deemed satisfactory for operational service in 1959, and it was formally type-classified as the M67 in August of that year. The US Army only reluctantly approved the M67 for service however, as its full weight had grown to 35 lbs (15.8 kg), and it still had unresolved cold weather reliability issues. The Army also gambled on introducing the M67 into service without the XM14 spotting rifle that was designed for it (which was ultimately never issued at all), and further delays in the production phase pushed-back the M67's achievement of operational status into 1963. All told, the M67's development had been much like its product; long, ponderous, and awkward, but ultimately effective.

   The layout of the M67 is typical of anti-tank weapons of its day, with a relatively straight, nondescript tube, and four brackets; a muzzle bracket, a foregrip bracket, a bipod bracket, and a breech bracket. The muzzle bracket helps maintain the tube's structural integrity, and is also typically wrapped with a hard rubber washer that serves as a simple shock absorber. The foregrip and bipod brackets are joined by a single assembly, which has the pistol grip and trigger group, a front monopod, and the sight assembly around the forward bracket, while the rear bracket only holds a bipod. Due to the monopod's placement on the bottom of the weapon, the pistol grip is located on the right side of the weapon, and the sight is canted to the left side; as a result, the M67 may only be operated from the left side. The bipod may be folded forward onto the bottom of the weapon and used as a simple shoulder rest, due to its distinctive pointed "P" shape. The breech bracket holds the propellant ignition assembly and a flared, shallow conical venturi with two slots. The venturi's hinge and the ignition assembly are both located on the right side of the breech bracket, while the lever used to open and close the breech is located on the left side. There is a cable to the breech assembly, which is used to activate the firing pin when the weapon is cocked and the trigger is pulled. When resting atop the bipod and monopod, the M67 sits 423 mm above the ground. US-operated M67s are typically olive drab in color, although they have sometimes been repainted in other colors and camouflage patterns.

   The weapon's tube, breech, venturi, pistol grip, monopod, brackets, and sight mounts are all made of steel. The bipod's composition is unclear, but appears to be made of an aluminum alloy. Conventional groove-and-land rifling is used in the M67, with has a right-hand twist, although the twist is extraordinarily long compared to the rifling typical of most small arms, with a turn in 18 m. The tube is air-cooled, with an interrupted thread breech, and has a lifespan of 2 000 rounds fired before the tube is expended.

   The M103 telescopic sight has a ladder-style reticule, with a sighting range of up to 800 m, in 100 m increments. It has a 10-degree field of view, a 3x magnification, and stadia lines also allow for lead at all ranges. The M103 is a day sight without any image intensification capabilities. No night sights were ever fielded for the M67, but the T25 Instrument Light device built into the M103 illuminates the sight reticule when activated. It is possible to use the M67 for indirect fire, but the M103 sight is only usable for direct fire engagements. Some M67s were fitted with the M103 sight, which included modifications to the stadia lines that allowed for aiming the XM591 round, but the XM591 was ultimately never issued.

   The M67 may be fired from a pintle or tripod (by attaching the weapon to one via the monopod), from the ground via the monopod and bipod, or from atop the gunner's shoulder. Much like a general-purpose machine gun, a crew of 3 is required to operate the M67; a gunner, an assistant gunner (typically called an "A-gunner"), and an ammunition bearer. The A-gunner also serves as the loader and the spotter, once the weapon is in position. When the weapon, gunner, and assistant gunner are all in position, the ammunition bearer provides security for the firing position. The M67 may also be fired from the gunner's shoulder in a standing, kneeling, or prone position, with increasing degrees of stability and accuracy from the former to the latter. In the prone position, the gunner and assistant gunner must lie in an orientation canted 60 degrees away from the axis of the weapon, as injuries may occur if their legs are inside the backblast area.

   To operate the M67, the weapon must first be emplaced or shouldered, the breech opened by turning the lockring clockwise until it unlocks the breech, and the safety near the pistol grip must be set from "fire" to "safe", if it hasn't been already. The breech is then swung-open laterally on its hinge, which also cocks the weapon, and a round is loaded into the breech. The breech is then swung shut and locked by turning the lockring counterclockwise, and when the assistant gunner is clear of the breech and backblast area, the safety is set from "safe" to "fire". Pulling the trigger engages the cable, which in turn activates the hammer in the venturi, striking the percussion cap in the round via the firing pin and firing the round. After the M67 is fired, the spent casing must be manually extracted.

   If the round does not fire, the gunner calls "Misfire", the assistant gunner repeats "Misfire", and the crew waits 1 minute before taking any action (in some instances, the percussion cap has ignited the propellant charge, but it doesn't combust instantly, and the round may cook-off or suddenly fire while the charge is burning; personnel thus must not open the breech until they are certain the round is a dud). The weapon is then safed, the breech is then locked and relocked, and the weapon is unsafed and the gunner again attempts to fire it. If another misfire occurs, the crew again waits 1 minute before taking any action, and this time the unfired round is unloaded and carefully discarded.

   The M67 is capable of burst fire at a rate of fire equivalent to 10 rounds/minute, but only until 5 rounds have been fired, after which the weapon must be allowed to cool before firing any additional projectiles. It is officially rated for an indefinitely sustained rate of fire of 1 round/minute, though combat experience has shown that 2 rounds/minute may be achieved without ill effect.

   The M67's effective range against stationary targets is 300 m, and its effective range against moving targets is 200 m. Beyond these ranges, the probability of a direct hit is less than 50%. The maximum range at 45 degrees of elevation is 2 300 m, though the odds of success even for saturation fire against area targets are quite low at this range.

   As with all US recoilless rifles, the M67's ammunition is "fixed", with the projectile and the propellant charge joined by a casing, forming a unitary cartridge. It fires the M112 cartridge, which is produced in 90x714 mm and 90x487 mm versions. Only three rounds were fielded by the US military; the M371 Taqrget Practice (TP), the M371A1 High Explosive Anti-Tank (HEAT), and the M590 Anti-Personnel (APERS). Of these, only the M590 uses the shorter casing. All of these rounds are fired via percussion cap in the base of the casing, which is ignited by the weapon's firing pin. The casings for the M67's ammunition are made of an aluminum alloy.

   The M371 TP is used as a target practice round for the M371A1 HEAT round, and has an inert warhead. It has the same weight, shape, and balance as the M371A1 HEAT round, so its ballistics are identical. The warhead of the M371 creates a puff of opaque smoke, and is detonated on impact by the Point Initiated, Base Detonated (PIBD) M530A1 fuse.

   The M371A1 HEAT round is rated to penetrate 350 mm of steel, 800 mm of reinforced concrete, or 1100 m of packed earth. It is effective against light armor and most 1960s-era main battle tanks, but the frontal armor of most main battle tanks introduced since 1970 is too strong for the M371A1 to penetrate. Moreover, the addition of reactive armor to many tanks with otherwise vulnerable armor has enormously reduced the effectiveness of the M371A1. It is also effective against unarmored vehicles, small structures, and enemy personnel in the open, but not nearly as effective as a generic high explosive round. As with the M371 TP round, the M371A1 HEAT is detonated on impact by the PIBD M530A1 fuse.

   The M590 APERS round is effectively a giant shotgun shell, filled with 2 400 nail-like flechettes. Commonly nicknamed the "Beehive", the M590 fires these projectiles in a wide fan, out to an effective range of 300 m. The flechettes are lethal at well beyond that distance, but the dispersion is too thin to reliably saturate a small group if enemy personnel beyond that distance (of course, human wave attacks are another matter). It is also very effective against lightly-built structures, unarmored vehicles, and helicopters, though the short range of this munition makes it less than ideal to attack these targets. Low-flying aircraft are also theoretically vulnerable to the M590, but the odds of actually hitting one are slim.

   The backblast of the M67 is quite spectacular --- and dangerous. It has an exceptionally broad 120-degree angle over a chevron-shaped area, with a 180 m wide diameter. The danger area extends from the breech to 28 m behind the firing position, while the caution area extends from 28 m to 43 m behind the firing position. The danger area must be totally free of personnel, loose debris, fragile materials, unsecure objects, and so on. Any personnel in this area are certain to receive severe injuries, and fatalities from the heat, gasses, and shockwave in this area are very likely. Personnel may safely remain in the caution area while the M67 is fired, though only with adequate precautions for eye and ear protection, and if cover is available against small flying debris.

    There was also a subcaliber training device developed for the M67, in the form of the M49A1. It is loaded and unloaded just like a regular round, but fires a special 7.62 mm tracer round with the same trajectory as the M371 and M371A1. The M49A1 thus allows M67 crews to practice with real weapons firing projectiles on the same ballistic trajectories as their "war shots", but without causing any tube wear.

   The M67 was first used in combat during the Vietnam War, and also during the US intervention into El Salvador in 1965. It was used heavily against personnel on the defense and fortifications on the offense during both of these conflicts, but it is unknown if M67s were used to engage armored vehicles in these conflicts. The Salvadorian military also used M67s in combat during the decade-long Salvadorian Civil War, though the rebel forces they fought had little in the way of armored vehicles, and no tanks. Thus, it is unknown if the M67 was ever fired in anger at a hostile armored vehicle.

    The introduction of the M47 Dragon anti-tank guided missile in the early 1970s saw the still relatively new M67 rapidly removed from the front lines, and by 1975, the US military officially retired the M67 entirely. However, for a "retired" weapon, the M67 was conspicuously busy in a number of crises during the Cold War. It remained in many US Army armories in West Germany until the end of that era, and the 6th Light Infantry Division in Alaska was still issuing M67s until at least 1988. The 4th, 5th and 6th Battalions of the 502nd Infantry Regiment, Berlin Brigade continued to operate M67s into 1992, out of concern that newer weapons were inadequate for the anticipating urban warfare that was expected to occur there in the event of a war with the Warsaw Pact, and two M67s were issued to C Co 5/87th (Lt Infantry) 193rd Infantry Brigade during Operation Just Cause, along with M590 APERS rounds. Combat engineer units continued to list the M67 as an essential component of their Modified Table Of Organization & Equipment as late as 1990, while the US Army Rangers also continued to use the M67 into the 1990s, not relinquishing them until an adequate replacement (the M3 MAAWS) was already in service. At some point in the 1990s, the US military finally relinquished all of their remaining M67s to the warehouses, but even that isn't the end of the story.

   Not only have foreign users of this weapon continued to employ it into the present day, but in 2011, M67s again returned to the battlefield. Still having large stocks of M67s, the US military found themselves in dire need of such a weapon during Operation Enduring Freedom, and following nearly a decade of intense pressure from the rank-and-file, the public, and Congress (and fierce resistance by the US military's leadership through this entire conflict), the US military finally re-issued M67s to the front lines in Afghanistan. In the Afghan War, they were quickly put to use for base defense, giving US troops an equalizer against the many RPG-series anti-tank rockets launchers and recoilless rifles used by the Taliban, as well as against attempted raids on forward operating bases. The Afghan Army was also supplied with M67s during this time, and by 2016, both Afghan and US troops were still using this elderly weapon in combat.

   The M67's Afghan adventure will likely be its "last hurrah" however, as its mission is increasingly being taken-over by the M3 MAAWS, and the M67's 90 mm ammunition isn't getting any younger or fresher over time. That, and it has still never knocked-out a tank in combat.

   Known operators of the M67 include Afghanistan, El Salvador, Greece, New Zealand, the Philippines, South Korea, the US, and Vietnam. The unit cost of the M67 and its ammunition are unknown, though production of both ceased long ago.

 

Similar weapons

 

   Carl Gustaf M2: This Swedish 84 mm recoilless rifle is very similar in design to the M67, though it is lighter and more compact. The Carl Gustaf was also operational for more than a decade prior to the M67's introduction, so it inevitably dominated the market. Interestingly, a variant of the following M3 model (the M3 MAAWS) became the successor of the M67 in US service.

   Ordnance, RCL, 3.45": British 3.45" (88 mm) recoilless rifle developed during World War 2, but not finally fielded until after the war ended. It can be fired from the gunner's shoulder, but is even more unwieldy than the M67. This weapon is most notable for its unique (and sublimely bizarre) employment of *four* conical venturis on its breech.

   LCD-APX: French 80 mm recoilless rifle similar to the M67. It was rejected by the French armed forces in favor of the LRAC F1 rocket launcher, and did not enter production.

 

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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M67 recoilless rifle

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