Photo By Daniel Marble | Capt. Eston Smith demonstrates a M240 coax ammo feeder prototype at a Maneuver...... read more read more
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FORT BENNING, Ga. – A persistent issue plagues Abrams tank crews during training exercises and at the gunnery range: ammunition jams on the M240 coaxial weapon system. The scenario is all too familiar: the loader fills the ammo box—sometimes using makeshift false bottoms like MRE boxes or ammo can lids—and charges the weapon. The gunner fires a few rounds, only to be interrupted by the unmistakable “clink!” of a jam.
These jams disrupt training and operations, consume valuable time, and divert the crew’s focus from the mission.
Understanding the challenge
Sgt. Major Vincent Behan, operations sergeant major for the 3rd Squadron, 16th Cavalry Regiment at Fort Benning, and a former senior instructor at the Abrams Master Gunner Course, has firsthand experience with this problem.
“The M240 coax, specifically on the Abrams V2 platform, consistently jams up due to ammo weight. It’s a well-known thing and an Army-wide issue,” Behan explains.
When the Abrams’ M240 coax is engaged, its ammunition must follow a complex feeding path: it travels up and out of the ammo box, across the box face, makes a 90-degree turn over the main gun, and descends toward the weapon before it can fire. This long and intricate journey, combined with the weight of the ammunition, increases friction and slows the feeding mechanism, leading to frequent jams.
“Even when you have a master gunner perfectly align everything, you’ll still go downrange and have failure to fire because the weight of the rounds is just too much for the gun to overcome,” Behan says.
“In a firefight, you don’t have time to build a false bottom or troubleshoot. A jammed M240 potentially removes thousands of rounds from the fight. It’s a dangerous operational vulnerability. So, when the (Maneuver Innovation Lab) opened, I thought, ‘Hey, I have this problem. Let’s see what they can do about it.’”
The DIRT Lab: inspiring Soldier-led solutions
In February 2025, Behan attended the grand opening of the MIL and discovered the Design, Innovation, Research, and Technology (DIRT) Lab. This space empowers Soldiers to submit unit-level problems through a QR code system, after which project managers collaborate with them to refine the issue and prototype a solution using the lab’s cutting-edge tools.
Curious about the process, Behan scanned the QR code and submitted his M240 coax problem on the spot. “Honestly, I just wanted to see how the submission system worked,” he admits. “If there’s something new I think could benefit my Soldiers, I’ll try it before suggesting it to them.”
Within days, the DIRT Lab team visited Behan’s unit to gather measurements and details about the M240 coax ammo box. Together, they began developing a solution to eliminate frequent jams and improve the weapon’s reliability.
Iterative design leads to an affordable, lethal solution
The DIRT lab team initially explored a follower-style mechanism, like those found in ammo magazines, to push rounds upward from the bottom of the box. However, as Behan recalls, “None of those configurations were really working out. It was taking up too much space and wasn’t as efficient as it could be.”
After further experimentation, the team shifted to a motorized roller prototype. They started by 3D printing a rolling sprocket that could pull rounds up and out of the ammo box, countering the downward force of the ammo belt. Next, they designed a housing for the sprocket, adding a small electric motor to assist in lifting the rounds, which reduced friction and strain on the weapon.
The motor is designed to draw power from the Abrams’ existing 24V system, seamlessly integrating with the M240 coax’s solenoid, an electromagnetic switch that controls the weapon’s firing sequence. When the gunner fires, power is simultaneously supplied to both the weapon system and the motorized feeder. The motor consumes less than 1 AMP of power, preserving energy for other critical systems on the tank.
To ensure reliability, the DIRT lab incorporated a one-way gear bearing for unidirectional feeding, allowing the gun to fire even if the motor fails. They also added a manual override, enabling the roller to function freely in case of a malfunction. The latest version of the feeder includes a guiding face on the sprocket housing, ensuring each round is correctly seated and ready to fire as it feeds into the M240 coax.
Importantly, the new feeder is designed to attach to the existing roller mount with no modifications to the ammo box. It secures with just two bolts, providing a straightforward and cost-effective solution. “We’re able to prototype these in-house for $30 a piece,” explains Capt. Eston Smith, the robotics liaison to the MIL for the U.S. Army Armor School. “It’s a straightforward solution to an Army-wide problem.”
Smith, along with other Armor Soldiers assigned to the MIL, assisted with the design and prototyping of the ammo feeder using the DIRT Lab’s manufacturing tools. He describes the design process in more detail in the included video.
Testing plans and future use
Preliminary tests of the motorized feeder using blank rounds have shown that the new system significantly improves M240 coax reliability by reducing the strain on the gun’s feeding mechanism by eliminating the weight of the ammunition in the ammo box. Additional features, such as a guiding face that realigns misaligned links, further enhance performance.
The DIRT Lab team plans to test the motorized feeder at a gunnery range later this year, with Behan serving as their master gunner during the test. This evaluation will allow them to assess the prototype in a real training environment, beyond lab conditions.
Smith estimates, “If our assumptions are right, this prototype will make the Abrams far more lethal as it should extend the capacity of the M240 coax from 400-600 rounds to its full 2,800-round capacity. It also makes the coax far more reliable, allowing the loader to focus strictly on loading the main gun and other critical tasks instead of worrying about the weapon system feeding properly.
With the ability to be 3D printed or assembled at any military innovation lab, the new ammo feeder can be rapidly deployed across the Army. Once finalized, blueprints and dimensions will be added to an Army-wide repository, making the design easily accessible for replication.
Reflecting on the project, Behan shares, “Changes don’t have to be huge to make an impact. They can come from any level, any echelon, and that’s where the MIL comes in—it’s local, accessible, and the team there wants to help.”
The MIL: driving the future of military innovation
“What started as a test of a new idea submission into our system has evolved into a tangible, impactful solution that could change Abrams training and operations across the force,” says Kyle Feger, interim director of the Maneuver Battle Lab, the organization that oversees the MIL.
“That’s the essence of the DIRT Lab: by tapping into the firsthand expertise of our Soldiers, we can generate innovative ideas and solutions that enhance the capabilities of the entire Army.”
Since its opening in February 2025, the MIL has become a hub for collaboration, uniting Soldiers, academics, and industry leaders to solve real-world challenges. A partnership between the Maneuver Center of Excellence’s Maneuver Battle Lab, the U.S. Army Combat Capabilities Development Command (DEVCOM), the Civil-Military Innovation Institute, Columbus State University, and Auburn University, the lab fosters creativity and problem-solving through access to state-of-the-art equipment, facilities, and expertise.
By prioritizing continuous improvement, the MIL enhances operational readiness and ensures the Army remains adaptable for future challenges.
For more information on the MIL or its DIRT Lab, please contact the Fort Benning Public Affairs Office.
| Date Taken: | 06.25.2025 |
| Date Posted: | 06.26.2025 09:56 |
| Story ID: | 501477 |
| Location: | FORT BENNING, GEORGIA, US |
| Web Views: | 85 |
| Downloads: | 0 |
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