US Army Precision Grenadier Counter-Drone Ammunition

Technical Summary

On 6 April 2026, the US Army published a solicitation for the Precision Grenadier System (PGS), a next-generation man-portable grenade launcher and integrated fire control system intended to replace or supplement the legacy Mk 19 Mod 3 40 mm automatic grenade launcher and M320 single-shot grenade launcher at the squad level. The solicitation calls for 16 prototype weapons, associated fire control systems, and approximately 25,000 rounds of ammunition across four natures: counter-defilade, counter-UAS, close quarters battle (CQB), and training.

The PGS programme aims to field two grenade launchers per rifle squad, providing organic capability against personnel in defilade, in structures, and — critically — against small Unmanned Aerial Systems (sUAS). The counter-UAS ammunition nature represents the most technically demanding requirement: a 40 mm round with a proximity fuze capable of detecting, tracking, and detonating within the lethal radius of a drone-class target without requiring external radar cueing or network connectivity.

The Army plans to award two Other Transaction Agreements (OTAs) for prototype development, with responses due by 11 May 2026. This procurement pathway allows rapid prototyping outside traditional Federal Acquisition Regulation (FAR) contracting timelines.

Analysis of Effects

The counter-UAS 40 mm airburst round must solve a specific terminal effects problem: generating a sufficient fragmentation density at an appropriate distance from the target to defeat a sUAS with a typical cross-sectional area of 0.05–0.5 m² and constructed primarily from plastic, carbon fibre, and lightweight electronics. This contrasts with the legacy M430A1 High-Explosive Dual Purpose (HEDP) round designed for point-detonation against materiel and personnel, which has a NEQ of approximately 32 g of Composition A5 (RDX-based).

An effective counter-UAS round would require a proximity fuze — likely employing either Doppler radar or laser rangefinding — programmed to detonate at optimal distance from the target, generating pre-formed fragmentation (tungsten or steel) in a controlled pattern. The airburst mechanism must discriminate between a sUAS and environmental clutter (birds, debris, rain) to minimise false detonations and fratricide risk.

The technical challenge is not the explosive effect but the fuze: a miniaturised proximity sensor reliable enough for squad-level employment without external sensor cueing.

The legacy Mk 19 Mod 3 fires 40 mm × 53 mm linked ammunition at a cyclic rate of 325–375 rounds per minute with a Maximum Effective Range (MER) against area targets of approximately 1,500 m and against point targets of approximately 1,500 m. The M320 fires 40 mm × 46 mm low-velocity grenades to a maximum effective range of approximately 350 m against point targets. The PGS solicitation does not specify which cartridge family the new system will use, raising the question of whether a new intermediate-velocity 40 mm cartridge or a completely new calibre is under consideration.

Hazard Division and Compatibility Group classification for the described ammunition natures would depend on the fuze type and packaging configuration per STANAG 4123 / AASTP-3. A proximity-fuzed 40 mm round with electronic initiation would likely be classified HD 1.1 or HD 1.2 depending on whether the fuze meets 2 independent safety systems per STANAG 4187. Classification depends on packaging configuration and fuze safety system status.

Personnel and Safety Considerations

The integration of proximity-fuzed airburst ammunition at squad level introduces safety considerations not present with legacy point-detonating 40 mm natures. Premature fuze activation, electromagnetic interference (EMI) susceptibility, and minimum arming distance are critical parameters that must be validated before operational fielding. The proximity fuze must incorporate mandatory safety features including a minimum safe separation distance and an electronic self-destruct or self-neutralise function to prevent unexploded ordnance (UXO) hazards.

Insensitive Munitions (IM) compliance under STANAG 4439 will apply to any new ammunition nature entering US service. The IM threat tests — Slow Cook-Off (SCO), Fast Cook-Off (FCO), bullet impact, fragment impact, shaped charge jet, and sympathetic reaction — must be completed during qualification. The electronic proximity fuze adds complexity to IM assessment, particularly under the bullet impact and fragment impact scenarios where electronic component damage could cause unintended initiation.

For ammunition technicians and WOME safety practitioners, the PGS programme signals a broader shift: the integration of “smart” fuzing technology into small-calibre ammunition previously considered low-complexity from a safety management perspective. This requires updated competences in electronic ordnance safety, EMI testing, and software-defined fuze assurance — areas covered under the UK Explosives Safety Authority National Occupational Standards (ESA NOS) Key Role 4 (Test and Evaluation) and Key Role 5 (Design and Engineering).

Data Gaps

DATA GAP: Cartridge calibre and velocity class — the solicitation does not confirm whether PGS uses existing 40 mm × 46 mm (low velocity), 40 mm × 53 mm (high velocity), or a new cartridge.

DATA GAP: Proximity fuze technology — whether Doppler radar, laser, or acoustic sensing is specified for the counter-UAS round is not disclosed in the public solicitation summary.

DATA GAP: Explosive fill and NEQ per round — the specific energetic material and Net Explosive Quantity for each ammunition nature are not stated in open sources.

DATA GAP: Minimum arming distance and self-destruct parameters — critical safety specifications for a proximity-fuzed airburst round employed at squad ranges.

Authoritative References & Evidential Record

Army Times — “US Army wants new grenade launcher, ammunition to be able to destroy drones” — 6 April 2026. [B/2]
Primary reporting on PGS solicitation with direct quotes from Army documentation. Established US military affairs publication.
Stars and Stripes — “Army seeks bursting ammunition for automatic grenade launchers to counter drone threat” — 3 December 2025. [B/2]
Prior reporting on the earlier Mk 19 counter-drone ammunition programme, providing developmental context for PGS.
The Defense Post — “US Army to Equip MK19 Grenade Launcher With Counter-Drone Capability” — 25 November 2025. [C/2]
Background on the Northrop Grumman M1167 proximity-fuzed 40 mm round development.
STANAG 4439 / AOP-39 — Insensitive Munitions Assessment Guidance. [A/1]
Reference standard for IM qualification of new ammunition natures.
STANAG 4123 / AASTP-3 — NATO Ammunition Classification and Hazard Assessment. [A/1]
Reference standard for HD/CG classification of proximity-fuzed ammunition.
STANAG 4187 — Fuzing Systems Safety Design Requirements. [A/1]
2 independent safety systems requirement applicable to new fuze designs.

Corrections & Updates
Corrections and updates welcome. If you hold open-source data that refines or corrects any parameter in this article, please contact [email protected] citing the specific claim and your source. Verified corrections will be incorporated and credited in the revision history.