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Soldier with Carl-Gustaf M4 and FCD 558 and thermal sight.

The power of communication

5 min read + Video

Developed with the help of customer feedback, Saab’s HE 448 round and FCD 558 fire control device for the Carl-Gustaf® system combine to solve even more battlefield challenges.

The nature of modern warfare is constantly evolving. To remain competitive, armed forces need to evolve, too, embracing new technologies and strategies.

At Saab, we have long understood that the same applies to the weapons that troops use. The most effective weapons are those that evolve to meet new challenges while still remaining simple enough to be easily used in the heat of battle.

It’s this kind of approach that has led to the creation of the latest additions to the Carl-Gustaf system. Developed through discussions with users, the HE 448 high-explosive round and FCD 558 fire control device take the Carl-Gustaf user experience to a new level, providing troops with solutions to common battlefield challenges.

Soldier with Carl-Gustaf M4 and FCD 558
Soldier with Carl-Gustaf M4 and FCD 558

The successor to the HE 441, the HE 448 is a powerful high-explosive round designed for use against unprotected troops, troops in defilade, and soft skin targets including vehicles. An interface in the round allows it to communicate with the new fire control device (FCD), greatly enhancing accuracy. Meanwhile, reduced weight and modifications to the composition help increase the  range, fragment distribution and lethality of the round. A fuze allows the HE 448 to be used in both direct attack and air burst mode.

“Through discussions with users, we discovered a need for an even more effective HE round,” says Saab Customer Service Representative Petter Grabbe. “However, our challenge was make improvements without adding any complexity for the soldier. Instead, we actually wanted to make it even easier to use.”

So, how do the HE 448 and FCD 558 combine to solve battlefield problems? And what key advantages do they bring to troops in the field?

More effective against body armour

According to Petter Grabbe, a common request among users has been for an HE round with better ability to defeat body armour. Such armour is increasingly being worn by hostile forces and can limit the effectiveness of fragmentation rounds.

Our designers addressed this challenge in several ways. One was to replace the mechanical fuze of the HE 441 with a much smaller electro-mechanical in the HE 448. At the same time, the 800 steel balls in the HE 441 have been replaced with 4,000 tungsten pellets in the HE 448, increasing fragment density and the overall probability of striking vulnerable areas on the enemy combatant.

Even greater range

Meanwhile, while our legacy FCD and HE round allowed the engagement of targets at up to 1300 metres, users looked for even longer range.

Our engineers listened and responded by reducing the overall weight of the HE 448 by 500 grams compared to the HE 441, down to a lean 2.7 kilogram. The reduced weight gives higher muzzle velocity and ability to cover more ground. At the same time, advances in ballistics (see below) ensure that not only does the HE 448 fly further, it is able to maintain outstanding levels of accuracy over that distance.

Increased accuracy in all conditions

A key concern for every fire team is first-round hits. Once you fire on the enemy, you make your own position known and become a clear target.

Special Forces with Carl-Gustaf M4 and 558
Soldier with Carl-Gustaf M4 with FCD 558
Carl-Gustaf ammunition High Explosive round HE 448
HE 448
Fire Control Device 558 for Carl-Gustaf M4
FCD 558

Petter explains that Saab engineers addressed the request for better accuracy by creating an interface between the round and the fire control device that allows for even more precise ballistic calculations. Via a protocol known as ‘Firebolt’, the round provides the FCD with exact information on the temperature of its propellant. This is a key factor in ballistics, as rounds with cooler propellant will generally travel slightly slower, while warmer propellant causes a round to travel slightly faster. The ballistic computer in the FCD 558 uses this information on propellant temperate to slightly adjust the round’s exit trajectory, greatly enhancing the chance of a first-round hit. This is particularly helpful for air burst mode where the round is set to detonate in the air just above the target.

Even simpler user experience

The Carl-Gustaf system is known around the world for its simplicity and durability. Hard work during the design process for the HE 448 and FCD 558 means its now simpler than ever to use the weapon.

For example, while the fuze of the legacy HE 441 round needs to be set manually prior to loading to enable air burst mode, the procedure for the HE 448 is far simpler. The gunner simply uses a toggle on the FCD to select the correct mode.

 

Similarly, while the legacy fire control system required different range knobs to be fitted depending on the round used, the digital interface on the FCD 558 removes this need. When a Firebolt-compatible round is chambered, the FCD is immediately able to identify the round type. Once the gunner inputs the range, the ballistic computer in the FCD uses the range, round type, attack mode along with propellant and ambient temperature to calculate the best trajectory for a successful hit. While the previous fire control system relied on mechanical adjustments to the achieve the trajectory, this is achieved electro-mechanically in the FCD 558. It is fully compatible with standard optical sights via a picatinny rail.

Meanwhile, a reduction in weight for both the fire control device and round reduces the burden that fire teams are required to carry.

Compatibility with legacy products

Finally, while the HE 448 and FCD 558 produce optimal results when used together, they are both compatible with legacy Carl-Gustaf systems. A legacy round will not be able to communicate its type and propellant temperature to the FCD 558. However, the gunner can simply enter the round type via a toggle to enable the ballistics computer to choose the correct trajectory.    

Meanwhile, the HE 448 can be fired using the legacy Carl-Gustaf fire control device, although only in direct attack mode.