Saab HEAT 758: Non-Initiating Precursor Architecture for ERA Defeat

Technical Summary

Saab AB has unveiled the HEAT 758, a new 84mm tandem High-Explosive Anti-Tank (HEAT) round for the Carl-Gustaf M4 (CGM4) recoilless rifle. The round is designed specifically to defeat Explosive Reactive Armour (ERA) tile arrays of the type fielded on contemporary Russian main battle tanks (T-72B3, T-80BVM, T-90M) and on a growing number of Soviet-legacy hulls retrofitted with Kontakt-5/Relikt panels. Reported main-charge performance is up to 700mm Rolled Homogeneous Armour (RHA) equivalent behind ERA. Effective range against point armoured targets is given as 600m. The round weighs approximately 3.7kg; the complete cartridge is reported at circa 7kg.

The headline design feature is a Non-Initiating Precursor (NIP). In conventional tandem HEAT geometries (for example AT4 CS-AT, RPG-29 PG-29V, Panzerfaust 3-T) the precursor is a small shaped-charge warhead that detonates the ERA tile to clear a path for the main charge. The NIP departs from this approach. Open reporting describes the precursor as physically traversing the reactive panel without initiating its flyer-plate sandwich, leaving a clean channel for the trailing main jet. The publicly reported mechanism is a low-density penetrator or jet that perforates the panel below the shock threshold required to detonate the sensitised explosive layer (typically PBX based on RDX or HMX in Russian ERA designs such as 4S22/4S23).

Analysis of Effects

If the NIP performs as advertised, the operational implication is significant. Conventional precursor detonation imposes a stand-off delay between precursor and main jet, during which the ERA sandwich’s flyer plate disrupts the incoming main jet by laterally displacing it. Defeating ERA without initiating it removes that disruption mechanism entirely. The main shaped charge then attacks the base armour through an undisturbed channel.

A reported 700mm RHA main-charge penetration value, achieved at 600m through ERA, places the HEAT 758 in the same penetration class as the RPG-29 PG-29V (~600–750mm behind ERA, per open Russian sources) and well above the legacy Carl-Gustaf HEAT 551 (~400mm RHA, no ERA defeat claim). The CGM4 platform’s muzzle velocity for HEAT rounds is in the 230–290 m/s band, consistent with the 255 m/s figure reported in some open accounts. This is a sub-sonic, fin-stabilised round — behaviour against cross-winds and through-foliage paths at the upper end of the engagement envelope will warrant operator characterisation. Firebolt fire-control integration with the Fire Control Device 558 should reduce gunner workload for the longer-range engagements.

For ammunition technicians the obvious questions are filler chemistry, hazard classification, and storage compatibility. Carl-Gustaf HEAT family rounds historically use Octol or RDX/Wax compositions for the main charge with sensitive booster trains; HEAT 758’s filler has not been disclosed. The round’s hazard classification is also undeclared in open source, but on type analogy with HEAT 551/HEAT 751 it will almost certainly be a UN Hazard Division (HD) 1.1 store with Compatibility Group (CG) E or F.

Personnel and Safety Considerations

Backblast and overpressure considerations for the CGM4 are not changed by the new natured round — the platform’s backblast danger zone remains as published in the CGM4 user manual. EOD and Ammunition Technician communities should expect: (1) updated In-Service Surveillance (ISS) protocols once the round enters NATO inventories; (2) revised Render-Safe Procedure (RSP) annexes covering the NIP precursor failure modes; (3) familiarisation training to distinguish HEAT 758 dud rounds from HEAT 551 and HEAT 751 visually and by radiographic signature, particularly relevant in coalition recovery operations where multiple Carl-Gustaf round naturals may be co-located. The dual-warhead geometry means a dud HEAT 758 contains two distinct energetic trains; RSP planning must address both.

Data Gaps

DATA GAP: filler composition and Net Explosive Quantity (NEQ) per round not disclosed; precursor mechanism described qualitatively only — no flyer-plate threshold data published; UN HD/CG and STANAG 4439 Insensitive Munitions (IM) classification undeclared; fuze designation and arming geometry not in open source; pricing per round and initial production quantities not announced; first NATO end-customer not identified at time of writing; live-fire validation against current-generation Russian ERA (Relikt, Malachit) reported by Saab but not independently verified.

AI-assisted technical assessment based on open-source material. Not a formal intelligence product. Source ratings (NATO STANAG 2022): Saab AB press release (B-2), Jane’s/EDR Magazine (B-2), Breaking Defense/Shephard (B-3). Where claims could not be independently verified they are reported as such.