Army Wants an Air-Bursting 40mm Grenade

U.S. Army weapons engineers are developing a new 40mm grenade that is designed to explode over enemy fighters hiding behind cover.

The Small Arms Grenade Munitions, or SAGM, will be twice as lethal as the current 40mm grenade against targets in defilade, according to Steven Gilbert, project officer with the Armament Research, Development and Engineering Center.

Gilbert, and a team of about 10 engineers within the Joint Service Small Arms Program, is trying to replace the standard 40mm grenade with an airburst model to be used against enemy in defilade positions.

“Warfighters currently lack the ability to achieve desired accuracy and incapacitating effects against personnel targets in defilade at ranges from 51 to 500 meters,” Gilbert said in a recent Army press release.

The new SAGM round is being designed for use in the M320 and older M203 grenade launchers.

Gilbert described the round as being complementary to the XM25 – the Army’s 25mm Counter Defilade Target Engagement System.

The 14-pound XM25 features a target acquisition system that calculates the target range with a push of a button, and transfers the data to the electronic fuse built into the 25mm round. When fired, the projectile is designed to explode directly above targets out to 600 meters, peppering enemy fighters with shrapnel.

Army officials halted operational testing in of the shoulder-fired, 25mm airburst weapon in February 2013 after a soldier suffered minor injuries when the weapon “malfunctioned” in Afghanistan. The weapon experienced a double feed and an “unintentional primer ignition” of one round, Army officials maintain.

Despite the setback, infantrymen who have fired the XM25 in combat say it’s effective at engaging enemy forces hiding behind the short mud walls commonplace across Afghanistan.

“SAGM is complimentary to that; we are not competing against it,” Gilbert explained. “The XM25 provides direct fire, SAGM is indirect.”

The SAGM project began in 2011, and the solution it seeks is not expected to be in the hands of Project Manager Ammunition Systems until July 2015.

The first phase of the project entailed making the fuze component smaller while maintaining the same functionality. The second phase was making the fuze smart by including sensors. The round detonates will detonate over and past defilade obstacles that are detected by the sensor.

During this phase, engineers worked to integrate sensors and logic devices to scan and filter the environment and autonomously airburst the fuze in the ideal spot, Army officials maintain.

With this new capability, which is fully autonomous on-board smart sensors, much like a smartphone, the grenade can perform a task without being told to do so by the user. It is designed so that, when fired, it will recognize its surroundings and can detonate over an obstacle that might conceal the enemy.

SAGM will have three firing modes, Gilbert said.

“Airburst after detecting defilade is the first,” he said. “The default is point detonation or when it hits the target. Lastly there is a self-destruct feature which decreases collateral damage and reduces unexploded ordnance left on the battlefield or training ranges.”

In addition to improved firepower, the SAGM round does not require the user to carry any extra gear or weapon accessories, advancing the goal of reducing soldier load, Army officials maintain.

Army engineers successfully demonstrated the Phase 2 sensor technology at Redstone Arsenal, Ala., in November 2013, Gilbert said.

“This capability will inflict maximum lethality to any enemy personnel seeking cover behind defilade,” he said.