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Next-Gen 40mm Airburst Ammo to Arm MK19 Grenade Launcher for Tactical Counter-Drone Defense.
The U.S. Army is moving to equip its MK19 40 mm automatic grenade launchers with programmable airburst counter-drone ammunition under a new Cornerstone Other Transaction initiative posted on SAM.gov. The effort would push dedicated, low-cost air defense against small unmanned aircraft down to squad and platoon level, tightening protection for vehicles, outposts, and maneuver units.
On 18 November 2025, the U.S. Department of War signaled a new phase in its fight against small unmanned aerial systems by preparing a 40 mm Counter Unmanned Aerial System (CUAS) capability for the MK19 automatic grenade launcher, as published on SAM.gov. Through a Special Notice issued under the Cornerstone Other Transaction Agreement, the Army outlines plans for programmable air-burst munitions designed specifically to defeat drones. The step reflects lessons from recent conflicts where commercial and military UAVs have become routine tools for surveillance and precision attack against ground forces and fixed sites. At the same time, allied nations report a steady rise in suspicious drone sightings over military and critical infrastructure in regions such as Europe, confirming that low-cost UAS are now a persistent security concern. For the U.S. Army, giving ground troops a dedicated CUAS ammunition family for a widely deployed weapon marks an attempt to push air defense capabilities down to the tactical edge.
In the picture, members of the 219th Security Forces Squadron from the 119th Wing, North Dakota Air National Guard, conduct live-fire training with the Mk 19 belt-fed 40 mm automatic grenade launcher at Camp Ripley, Minnesota. On 18 November 2025, the U.S. Department of War signaled a new phase in its counter-drone efforts by preparing a 40 mm Counter-Unmanned Aerial System capability for the Mk 19 (Picture source: 119th Wing ND Air National Guard)
The Special Notice describes how the U.S. Army Combat Capabilities Development Command – Chemical Biological Center (DEVCOM CBC), acting on behalf of the Office of the Secretary of Defense and the Assistant Secretary of Defense for Industrial Base Policy, intends to launch a competitive Cornerstone Initiative Request for a 40 mm CUAS solution. The objective is to integrate advanced proximity-sensing fuze technology into programmable 40×53 mm air-burst cartridges for the MK19, turning a long-serving grenade machine gun into a specialized counter-drone effector. This effort is framed as a complete system: not only a new cartridge, but also the required detection, tracking, targeting and defeat functions, with seamless integration into existing weapon platforms, fire-control systems and remote weapon stations. By insisting on compatibility with current MK19 mounts and remote stations, the Army aims to minimize the need for new hardware while enabling vehicles, perimeter towers and dismounted units already equipped with the weapon to adopt the CUAS role through an ammunition and software upgrade.
The MK19 offers a robust platform for this evolution. Introduced during the Vietnam War and fielded widely in the late 1960s and 1970s, the belt‑fed 40 mm automatic grenade launcher is a standard support weapon across U.S. services and numerous allied forces. Its 40×53 mm high‑velocity cartridges, sustained rate of fire, and effective engagement ranges, approximately 1.5 km against point targets and beyond 2 km against area targets, have established it as a reliable choice for convoy protection, base defense, and direct fire support. Recent industry trials with time‑programmed and air‑burst munitions have demonstrated that the launcher’s basic mechanism can accommodate more sophisticated fuze functions. The CUAS initiative advances this capability by specifying proximity‑sensing fuzes that detect an unmanned aerial system and detonate at an optimal distance, markedly improving the probability of defeat against small, agile targets without requiring a direct hit. This concept follows the precedent of adapting legacy munitions, such as guidance and fuze kits for Hydra 70 rockets, to create tailored counter‑drone effects.
From an operational standpoint, 40 mm counter-unmanned aerial system (CUAS) ammunition occupies a distinct role within layered air defense architectures. High-end gun systems such as 30 mm and 35 mm turrets with programmable rounds and missile-based solutions deliver superior range and hit probability, yet they remain costly, limited in availability, and typically confined to larger platforms. In contrast, the MK19 launcher is already integrated across a broad spectrum of light and armored vehicles, as well as employed on tripods for dismounted missions and on naval mounts. Outfitting these existing systems with programmable proximity-fuzed ammunition and the corresponding fire-control enhancements would provide platoons, company-level units, and base defense teams with an organic, high-capacity hard-kill capability against low, slow, and small drones within short-range engagements. The comparatively low cost of 40 mm ammunition relative to missile systems further positions it as an efficient option for countering frequent, low-value aerial threats such as commercial quadcopters used for reconnaissance or ordnance delivery. The primary constraint remains projectile velocity and flight trajectory; grenade rounds travel more slowly than cannon shells, limiting their effectiveness against fast or highly maneuverable targets and underscoring the need for precise sensor cueing and advanced fire control.
Routing this development effort through the Cornerstone Other Transaction Authority (OTA) reflects strategic intent beyond the immediate tactical advantage. The Cornerstone initiative was established to enhance the U.S. defense industrial base by fostering enduring partnerships between the government and a consortium of industry participants, and this CUAS program aligns directly with that objective. Leveraging this framework enables the Department of Defense not only to prototype a critical capability but also to cultivate an industrial ecosystem capable of sustaining the production of advanced 40 mm munitions and their supporting electronic components. The increased prevalence of drones in conflicts ranging from the Middle East to Eastern Europe, along with their growing appearance over domestic military sites, suggests that demand for anti-drone munitions will continue to rise. Tying the development of a new 40 mm CUAS round to the widely fielded MK19 therefore achieves dual goals: it delivers a practical counter-drone solution to front-line forces and embeds a new class of programmable munitions within a structured, resilient industrial base.
By turning a legacy grenade launcher into a dedicated counter-drone platform, the U.S. Army is responding to a clear operational trend: ground forces can no longer rely solely on high-end air defense units to deal with small unmanned aircraft. If the forthcoming Cornerstone Initiative Request leads to a successful prototype and follow-on production, MK19 crews could gain the ability to engage drones with tailored 40 mm air-burst rounds from positions and vehicles they already occupy. At a time when small UAS are proliferating over front lines, supply convoys and even training areas, the move to field 40 mm CUAS ammunition signals a broader shift toward making every echelon of ground troops part of an integrated counter-drone architecture, rather than leaving the mission to specialized systems alone.
Written by Teoman S. Nicanci – Defense Analyst, Army Recognition Group
Teoman S. Nicanci holds degrees in Political Science, Comparative and International Politics, and International Relations and Diplomacy from leading Belgian universities, with research focused on Russian strategic behavior, defense technology, and modern warfare. He is a defense analyst at Army Recognition, specializing in the global defense industry, military armament, and emerging defense technologies.