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Carl-Gustaf M4

A battleground hero

Developed in the 1940s and as relevant in today’s technology-driven theatres of combat. A clever basic design that has been constantly innovated, and that is now used by more than 40 nations across the planet. The story of Saab’s Carl-Gustaf is the story of a Swedish battleground hero.

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Robust, smart and reliable - whenever deployed

In October 1993, Swedish Brigadier Ulf Henricsson led the first Nordic UN batallion in Vares in Bosnia, saving up to a thousand people’s lives when the village was under threat during the Balkan Wars.

"We succeeded because we had better equipment than they had. And they knew it.”
Ulf Henricsson, retired Brigadier in the Swedish Armed Forces

“Our success in large parts depended on the fact that we were well-equipped and dangerous” says Henricsson.“We showed them that we were ready to be very dangerous. The reason was that we really had better equipment than they had. And they knew it.”

Saab’s recoilless rifle Carl-Gustaf was part of the battalion’s arsenal, playing a vital part in scaring the attackers into submission.

“We didn’t need to shoot a single live round from it.”
Dismounted combat troops have one of the toughest jobs in the armed forces. They engage the enemy on an intimate basis, often operating just metres from their opponents in complex, noisy and rapidly evolving environments. To succeed – and survive –they need to be agile and to be able to respond rapidly.

Malcolm Arvidsson, Head of Product Management for Business Unit Ground Combat at Saab, explains that in such environments, weapon systems need to be reliable.

“You can’t have a weapon that’s too complex and that might let you down,” he says. “You need simple, robust systems that will work every time and when you really need them.”

Malcolm Arvidsson
Malcolm Arvidsson, Head of Product Management for Business Unit Ground Combat at Saab

Enter the Carl-Gustaf man-portable recoilless rifle system. Since being developed in the 1940s, the system has proved reliable in countless conflicts around the planet. Its simple, robust design and adaptability has made it the first-choice dismounted combat weapon for over 40 nations, including the United States and many European countries.

Wide range of rounds

From an initial offering of just two rounds, today’s Carl-Gustaf systems are compatible with 11 different rounds, allowing it to be tailored for use with any mission. Most commonly employed by a two-man team (a gunner and a loader carrying the ammunition), it is capable of anything from anti-tank strikes to bunker-busting to battlefield illumination.

“The Carl-Gustaf is a true multipurpose weapon. It has anti-armour and anti-structure capabilities, it can defeat soft targets in the open, and it also has support capabilities like smoke and illumination. Armed forces use the system everywhere from arctic environments, down to the tropics and in deserts.”
Malcolm Arvidsson, Head of Product Management

Designed for repeated use with a wide range of tailored rounds, the Carl-Gustaf system is also extremely light. Weighing less than 7 kilograms, the weapon can be easily slung over a soldier’s shoulder. With the 84mm rounds weighing between 2.6 and 4.8 kilograms, a two-person team of gunner and assistant gunner can easily transport an impressive support capability.

The first Carl-Gustaf weapons produced for the Swedish military in 1948 represented an impressive technological leap forward. Based on the barrel of an 84-calibre 19th-century canon, the rifled barrel and innovative recoilless firing system allowed the Carl-Gustaf to fire relatively large calibre rounds at much higher muzzle velocities than rival systems, resulting in greater lethality, accuracy and range.

Carl-Gustaf M2
Carl-Gustaf M4

While the overall design of the system has remained constant since then – a gunner from 1948 could fire today’s system without almost no training – there has been constant innovation around components.

Constant evolution

Saab has worked tirelessly to evolve the features of the weapon and its sights to ensure they meet the demands of modern troops. The release of the M4 saw the overall weight of the system reduced by more than three kilograms through the use of light-weight materials, such as titanium alloy, and an optimised design. Saab engineers also reduced the length of the weapon by 6cm and improved the overall ergonomics. “We recognised that the weapon should be as light and manoeuvrable as possible because light infantry are often operating in tight spaces and jumping in and out of vehicles and buildings” Malcolm Arvidsson says.

Another factor in the Carl-Gustaf’s ongoing popularity is the nature of warfare. While technology has removed the human factor from some theatres of conflict, it remains crucial in others.

“In many parts of the world, the threat environment is not symmetrical,” he says. “Over the past 20 years, there’s been a rise in conflicts where the enemy is inside buildings in an urban environment. Engaging the enemy threat requires boots on the ground, and the troops involved need a weapon to solve their challenges.”

The sights for the Carl-Gustaf system have also undergone significant innovation. “The M4 can be fitted with an intelligent sight that can communicate with the rounds to increase the probability of hit,” Arvidsson says. “The sight looks at factors like the temperature of the propellant to carry out more accurate ballistic calculations. The gunner can choose whether a round should airburst, explode on impact, or penetrate a wall.” Meanwhile, guided missile munitions are also under development that would potentially allow system users to guide a round once it has been fired.

Proudly Swedish

While the Carl-Gustaf system was initially produced for use by Sweden’s military, an extensive export business began in the 1960s to provide other nations' armed forces with the system. Arvidsson says while rival systems can offer some of the Carl-Gustaf’s features, none can offer all. “With the Carl-Gustaf system, the firing system is mechanical, so it works when you need it to. It’s light-weight, it’s versatile and it has a simple maintenance schedule. You would typically need two or even three other systems to solve all the challenges that Carl-Gustaf does.”

The system was born from Sweden’s desire in the 1930s and 40s to produce its own defence equipment and not be dependent on other nations. Arvidsson remarks that, as a result, it has certain Swedish characteristics. “It doesn’t overdo anything,” he says. “It’s built and designed for its purpose. It’s very robust, has a smart design and is extremely reliable. And the quality is high, which is something I think Sweden stands for.”

The evolution of a battleground hero

Carl-Gustaf M4

At just below 7 kilograms, the Carl-Gustaf has lost half its weight since the first version 70 years ago. Follow the evolution from 1948 until today.

It was after World War II that Swedish arms designers really got to grips with developing recoilless anti-tank launchers that could be fired from the shoulder of infantrymen. With the gradual disappearance of light tanks and introduction of infantry support vehicles with much thicker armour, a more effective anti-tank defence system with a better level of penetration than a regular projectile was required.

Carl-Gustaf M2

That’s when they came up with the concept of using shaped-charge high-explosive anti-tank (HEAT) warheads, which penetrate thick tank armour. Captain Harald Jentzen, Hugo Abramson and Sigfrid Akselson were behind the early construction and development of the Carl-Gustaf, eventually introducing the single-shot calibre 84mm grenade rifle (or “granatgevär” in Swedish) in 1948. Used by the Swedish Army, this early version was simply called the m/48 (the term M1 being coined later on for the overseas version).

Carl-Gustaf M4
Now, 70 years on, the Carl-Gustaf is much more than just an anti-tank grenade launcher. Its tactical role has been extended, and it can be loaded with a whole range of ammunition including high-explosive fragmentation rounds, shrapnel rounds, smoke and illumination.

Carl-Gustaf today

Being both lighter and shorter than its predecessors, today’s M4 has the same loading and firing system, with a two-man team comprising a gunner and a loader required for its efficient operation. The gunner takes up their position and the loader checks that the risk area behind the weapon is clear.

The locking lever, an inbuilt safety system, allows the M4 to be carried around while loaded. Clearly beneficial, this means that the gunner no longer needs to venture out unarmed into vulnerable terrain before loading the weapon.

The high-tech electronics on the M4 also set it apart from the purely mechanical nature of earlier Carl-Gustaf systems. It has a shot counter, which means that soldiers no longer need to make a note of the number of full calibre rounds they have fired. Secure in the knowledge that they have up to 1,000 live rounds to fire, they can be confident that the computer-connected system will monitor the weapon’s maintenance needs for them. The operator is also able to keep hold of the handle while using a joystick or fingering a touchpad on the side of the weapon to scan the menu of its capabilities: hence remaining in control of the system at all times.

While both the Carl-Gustaf and its ammunition are progressing with the times, the calibre of 84mm has been retained, which makes every version of Carl-Gustaf compatible with any ammunition. The Carl-Gustaf M4 is compatible with older ammunition dating back to the days of the M1.

The evolution of Carl-Gustaf over the past 70 years

1948

1948: The m/48 (it became known as the M1 elsewhere in the world) is introduced in Sweden – the rifle part is 1,130mm long, and the complete system including its stand and sight weights 14kg.

1958

The name Carl-Gustaf is introduced.

1964

The introduction of the M2. Made for export, it had a reinforced barrel capable of withstanding the pressure of a warmer climate in places like India and Australia. The same length and weight as M1, the M2 was classified by NATO.

1986

The arrival of the Carl-Gustaf M3 – 1,065mm long, with a lighter barrel made of a carbon-fibre-reinforced thin steel liner, which is 0.4mm thick at its thinnest point.

2014

The arrival of the current M4 version of the system, a future-proof digital weapon – with a steel-free titanium-lined barrel and titanium venturi, it is stronger than the M3, although it weighs under 7kg excluding the sight and stand, and is just 999mm long.

One rifle – eleven weapons

Compatible with 11 different rounds, the Carl-Gustaf system can be tailored for use with any mission or environment. It has anti-armour and anti-structure capabilities, it can defeat soft targets in the open, expose the enemy with illumination or provide concealment through smoke.

5A7360E4-CE78-4CA6-8E27-0AB6CF888C1C Created with sketchtool.

Saab produces four types of anti-armour rounds for the Carl-Gustaf, including one against reactive armour, two single-warhead, rocket-propelled rounds, and a confined space round with a different propulsion system for use inside buildings and in complex. Anti-structure rounds for the system include the ASM 509, which is designed for use against buildings, and the Multi-target round MT 756, featuring a tandem warhead which first punches a hole through a wall and then detonates behind the wall. Anti-personnel rounds include the Area Denial Munition round ADM 401, which is designed for defeating close-range soft targets like cars, and the High Explosive round HE 441 which features a time fuze, allowing for airbursts defeating targets behind cover.

Finally, support rounds include a parachute-suspended illumination round ILLUM 545C to expose enemy forces at night and a smoke round SMOKE 469C to provide concealment.

“It’s unlikely that you would need all 11 types of a single mission, and that is not the idea,” says Malcolm Arvidsson. “Instead, you would pick the rounds you need and shape the system to suit the mission.”

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“Working with the Carl-Gustaf system is special because of its history and that all the previous versions are still in use. Any new munition needs to be compatible with all the previous versions. We always need to consider the historical heritage.”
Åsa Windfäll Development, External ballistics

How the HEAT charge works

Inside the shaped high-explosive anti-tank (HEAT) charge, the kinetic energy released by an explosion is focused on a particular point, allowing it to pierce steel that is very thick. (In other words, the round does not heat or melt the metal it comes into contact with, despite the acronym HEAT.)

The shaped charge device comprises a hollow cylinder containing explosives that are placed behind a metal liner casing. A detonator located behind the explosives ignites them, releasing a high-velocity detonation wave and creating a high-pressure front which expands the metal casing, making it shoot forward in the form of a narrow jet. With its lance-like profile, this jet is able to penetrate reinforced structures including steel plate and concrete. The high velocity jet causes the target to undergo plastic deformation under the pressure of the jet.

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Firearms for the future

Cutting-edge capability, intelligent sights and programmable ammunition. The Carl-Gustaf system is all set for the integration of the enhanced rounds that the future will bring. Here’s a look at the road ahead.

Think of a round so accurately guided that it will smoothly find its own way to a target 2,000 metres away, minimizing the risk of collateral damage. That’s the future of ground warfare – at least when it comes to Saab’s proposed next-generation ammunition for the Carl-Gustaf system. Such next-generation rounds are currently being developed as part of Saab’s Guided Carl-Gustaf Munition (GCGM) programme, the aim being to ensure customers the highest level of accuracy at a long range – all from the weapon system that they already have in service.

Johan Ekeroot, Director Product Management, Programmes at Saab’s Business Unit Ground Combat says, “Using a guided ammunition we’re providing pinpoint accuracy even at ranges up to 2,000-metres with similar target capability as the regular rounds and with reduced risk for collateral damages. You just pull the trigger and the round will do the rest. I promise you that.”

The soldier simply aims at the target, locks the seeker to it and fires the round in the right general direction, then the round takes over. Launched at a relatively low velocity, it picks up speed along its path as the flight rocket motor is started, and proceeds to home in on it’s target. The seeker in such a round allows it to track stationary and moving, providing high success rates even at long range without increasing the workload required by the gunner.

High precision minimizes collateral damage

While some of today’s unguided rounds rely on the fragments they release to hit their targets, the guided round being designed for the Carl-Gustaf weapon system at Saab guarantees a precise hit and an high effect in the target with a reduced amount of fragments being released far from the point of impact. But to achieve this, there are plenty of elements that need to be fitted into the 84mm calibre barrel of the Carl-Gustaf M4, which is just under a metre long. And that, says Ekeroot, is quite a challenge. These elements include:

  • the seeker
  • the electronics section
  • the tandem warhead
  • deployable wings and fins
  • the ignition system and Safety Arming Device
  • the control activator system – a drive which executes the commands from the guidance system by controlling the fins
  • the two-stage rocket propulsion

It has to happen, says Ekeroot. “We’ve already given the world the M4: a lightweight, customisable weapon system with communications capability between the sight and the round. We can already fire a non-guided round at a target up to 1,500 metres away… With the guided round we will provide the ability to attack point targets with high accuracy at even longer ranges, both moving and stationary.”

Partners on the programme

Current phases of the GCGM programme is privately financed. Saab and US-based Raytheon are sharing the workload on developing this latest cutting-edge ammunition on a 50/50 basis. While Saab is providing the necessary warhead and propulsion capabilities, Raytheon has brought its seeker, guidance and control systems to the table.