WOME Intelligence Anti-Armour NATO Procurement

HEAT 758: Saab’s Non-Initiating Precursor Reshapes the Carl-Gustaf Anti-Armour Round

An 84 mm tandem round that perforates Explosive Reactive Armour without detonating it — combined with rocket-assisted reach to 600 m and Firebolt fire-control integration — gives the Carl-Gustaf M4 a credible answer to KONTAKT-5 and RELIKT-class threats.

Image: © Saab AB

Saab announced on 7 May 2026 the launch of HEAT 758, a new 84 mm tandem-warhead round for the Carl-Gustaf M4 recoilless weapon. The round was demonstrated at a live customer firing in May at the Bofors Test Center, Karlskoga. An undisclosed Carl-Gustaf customer has placed an order and Saab confirms production is underway.^[1]

For practitioners working on shoulder-launched anti-armour capability, HEAT 758 is more than a portfolio refresh. The round’s headline novelty is not the tandem geometry — that has been Carl-Gustaf doctrine since the HEAT 751 — but the precursor itself. Saab has implemented what its development partners describe as a Non-Initiating Precursor (NIP): a sub-calibre element that physically traverses the Explosive Reactive Armour (ERA) panel without detonating the brick, and that leaves a clean, residue-free channel for the main charge to follow.^[2]

The Technical Pivot: Non-Initiating Precursor

Conventional tandem anti-armour rounds defeat ERA by detonating the precursor charge against the bricks — the sympathetic detonation strips reactive material from the path of the main charge. The trade-off is well understood: the precursor blast disturbs the channel, can deflect the main charge jet, and leaves residual fragments that degrade penetrator performance.

Saab’s Non-Initiating Precursor approach reverses the design logic. Rather than detonating the ERA brick, the NIP physically perforates the casing and explosive layer at velocities and pressures below the brick’s initiation threshold. The mechanism has not been disclosed in open sources — commentators have inferred a low-density jet or kinetic-energy projectile — but the operational outcome is documented: a clean, residue-free channel with minimal hydrodynamic disturbance, allowing the main shaped-charge jet to form and penetrate at near-theoretical maximum efficiency against the primary armour array.^[2][3]

According to Saab’s development account, the NIP geometry was optimised using artificial intelligence and machine-learning tools, with more than 50,000 computer simulations evaluated to identify the configuration with the highest performance against all three generations of Russian reactive armour: KONTAKT-1, KONTAKT-5, and RELIKT.^[3] RELIKT in particular — a 2006-era double heavy-plate design fitted to T-90 and T-14 variants and roughly twice as effective as KONTAKT-5 against shaped-charge threats — has been the high-end ERA challenge for current-generation infantry anti-armour weapons; a credible answer at the 84 mm shoulder-launched tier is non-trivial.

The implication for ERA designers is asymmetric. Defeating a Non-Initiating Precursor requires brick architectures that initiate at lower threshold pressures, or multi-layer / redundant reactive arrays. Both add weight and complexity to the host platform, and both impose trade-offs that an integrator cannot solve in software. The 7 May demonstration at Karlskoga reportedly engaged a T-80 main battle tank target at 500 m in front of an international audience that included Ukrainian officers — a deliberate signal about the threat set the round was designed against.

Performance and Engagement Envelope

Saab declares main-charge penetration of up to 700 mm of Rolled Homogeneous Armour-equivalent behind ERA — a +200 mm (+40 %) uplift on the predecessor HEAT 751’s nominal 500 mm RHA-equivalent figure.^[4] At that level the round is credibly targeted at the heaviest current-generation main battle tanks, including those fielded with composite armour packages and supplementary reactive-armour suites.

Engagement range has also extended. HEAT 758 is a rocket-assisted projectile (RAP) in the FFV 551 / HEAT 751 lineage — the round leaves the muzzle at approximately 210 m/s under the recoilless gun’s charge, then ignites a sustainer rocket motor post-muzzle to accelerate to a flat-trajectory speed in the order of 330–340 m/s. That extends the maximum effective range to 600 m against point targets — a 100 m (+20 %) gain over the HEAT 751’s nominal 500 m envelope.^[2] For operators that translates into meaningful additional standoff in open or semi-open terrain where engaging an ERA-equipped vehicle is otherwise a high-risk encounter at sub-400 m ranges.

Crucially for fielded units, the round’s complete weight is approximately 3.7 kg — near-identical to the 3.8 kg HEAT 751 it succeeds. Form-factor parity matters: it minimises operator retraining, keeps existing magazine and load-out fittings valid, and allows mixed-round handling within the same Carl-Gustaf section without doctrinal change. A capability uplift that arrives without a logistics tail is the rare procurement combination.

Source: Saab press release (7 May 2026), Calibre Defence, Future Warfare Magazine, METIS Munition Database. Figures are vendor-declared or open-source consensus; not independently tested.

Firebolt Integration: Why Communication Matters

HEAT 758 is engineered around Saab’s Firebolt two-way communication interface, which means the round is not a passive cartridge but an active node in the fire-control loop. When chambered in a Firebolt-enabled Carl-Gustaf M4 fitted with the Fire Control Device 558 (FCD 558), HEAT 758 announces its identity to the sight, communicates propellant temperature, and accepts ballistic and (where applicable) fuze settings programmed by the gunner.^[5]

The first Firebolt-native round was the HE 448 high-explosive cartridge with selectable impact and airburst modes, fielded from late 2022. HEAT 758 extends Firebolt into the anti-armour role — but with a different value proposition. Where the HE 448 used Firebolt principally for fuze mode programming (impact vs airburst, with airburst-height selection), HEAT 758 is impact-fuzed and uses Firebolt principally for ballistic accuracy. Range-finding and ballistic-table selection — tasks that previously sat in the gunner’s head and on the back of the launch tube — are now handled in the FCD 558’s ballistic computer with sensor inputs for air pressure, propellant temperature, and operator-entered or laser-derived range. The FCD 558 fuses these inputs with stored ballistic tables and applies an automatic sight adjustment.

The result is a meaningful first-round hit-probability gain at the 400–600 m engagement band where the rocket-motor-assisted envelope is now decisive, and a corresponding reduction in gunner cognitive load. For a shoulder-launched system that is, by design, used in seconds-not-minutes engagements against ERA-equipped armour, accuracy at the new outer edge of the envelope is the dominant capability driver.

The Procurement Layer — Will HEAT 758 Land in the NSPA Framework?

Saab and the NATO Support and Procurement Agency (NSPA) signed a multi-year framework agreement for the Carl-Gustaf M4 family in March 2023, covering both weapon systems and ammunition. The framework is reported to run until 2027, and has already generated call-off orders worth approximately SEK 350 million with deliveries scheduled across 2023–2025.^[6][7] The Carl-Gustaf framework sits alongside Saab’s parallel AT4 framework with NSPA and is one of the access mechanisms by which NSPA Ammunition Support Partnership (ASP) participating nations consolidate demand — the ASP framework currently counts 26 NATO and partner nations.^[8]

Whether HEAT 758 is added as a callable line item under that framework is not yet a public decision. The framework structure is ammunition-portfolio-wide rather than round-specific, which means a new variant can in principle be incorporated as Saab catalogues it and as participating nations express requirement — but only after the round has cleared the relevant national qualification, in-service safety case, and any framework-level technical baseline review. Three indicators are worth tracking:

• Identity of the launch customer. Saab has confirmed an order from an undisclosed customer with production underway. If the launch customer is an NSPA ASP participant, the qualification path into the framework shortens materially.
• Framework re-baseline timing. With the existing agreement running to 2027, the realistic window for HEAT 758 inclusion is the next 12–18 months — either as a framework amendment or as a successor agreement covering 2027 onwards.
• Round-level safety qualification. Inclusion in any NATO-coordinated procurement requires evidence of qualification under STANAG 4170 (principles for selecting and qualifying explosives for military use) and the relevant ammunition-system safety case. Saab’s public communications indicate the round is in production; the in-service safety release status of each procuring nation will determine pace.

The structural answer is that the existing framework is designed to absorb new Carl-Gustaf variants, and HEAT 758’s capability profile against KONTAKT-5 and RELIKT-class threats is precisely the requirement that the eastern-flank NSPA participants are signalling. The procedural answer is that the round will move into framework call-off only after at least one ASP nation completes qualification — which is when ISC will be able to put a date on the answer rather than a probability.

What to Watch Over the Next Six Months

Three trackable signals will indicate whether HEAT 758 is becoming a NATO-baseline anti-armour round or remains a single-customer capability. (1) Qualification announcements — any of the eastern-flank NSPA ASP nations declaring HEAT 758 in-service. (2) Framework activity — an NSPA call-off explicitly naming HEAT 758, or an amendment notice to the 2023 Saab–NSPA framework. (3) Industrial signal — production capacity announcements at Karlskoga or at Saab’s new Indian production facility, since round-specific capacity is the leading indicator of order-book depth.

For the WOME and EOD community, the most consequential downstream item is the precursor energetic fill (if any) and the hazard classification of the round as a system. If the NIP mechanism uses a non-standard energetic, an unusual liner material, or a purely kinetic configuration, the round’s Net Explosive Quantity, hazard division, compatibility group, transport categorisation, storage Quantity-Distance envelopes, and disposal procedures will all diverge from the HEAT 751 baseline. EOD operators will need updated UN packaging codes and Material Safety Data Sheet equivalents before the round enters operational stockpiles. ISC will return to this when the technical data sheet is in the public domain.

This analysis is AI-assisted and based on open-source materials. It does not constitute investment, legal, procurement, or technical safety advice. Source evaluation follows NATO STANAG 2022 (Reliability A–F / Accuracy 1–6). Acronyms are expanded on first use.