The Army is moving forward with its “Third Arm” technology, which aims to relieve gear-heavy soldiers while improving accuracy.

Engineers at the Army Research Lab in Maryland developed a device designed to hold a soldier’s weapon while displacing the weight from the arms to the torso.

The Third Arm was unveiled at the AUSA conference last year in Huntsville, Alabama, and six soldiers tested it during a pilot study last summer.

These soldiers volunteered to wear electromyography sensors to measure muscle activity, according to the Army. The soldiers then fired weapons with and without the Third Arm.

The mechanical arm doesn’t fire the weapon itself, but it helps reduce the weight a soldier is carrying. Holding a weapon or shield for a long time causes the arm to shake, which can decrease shooter accuracy.

“We found that it reduced the fatigue and reduced the muscle activation for some soldiers,” Dan Baechle, a mechanical engineer at ARL, said in an Army news release.

However, Baechle said some soldiers had problems with the device, which caused the lab to build an improved second prototype.

These improvements included changing the mounting location from the front of the vest to the back and adding an extendable hinge plate to fit different sizes and body types.

Baechle said he wants feedback from more soldiers before the Army fields the system.

The second prototype of the system weighs 3.5 pounds and is set to be tested by at least 15 soldiers this spring.

The Third Arm can support such weapons as the M249 light machine gun, which weighs about 27 pounds, the release said.

Besides weapons, it can hold 20-pound shields with a mount that connects from the mechanical arm to the shield.

The idea of the Third Arm began in 2015 when ARL researchers were working on how to make dismounted soldiers more lethal. The first prototype was built in 2016 and was unveiled at AUSA in March 2017.

Future tests of the device will address moving targets, shooting on the move, unconventional firing and recoil mitigation.

Charlsy is a Reporter and Engagement Manager for Military Times. Email her at

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