The U.S. Army is developing a “third arm” device that can be attached to a soldier’s protective vest to hold a weapon. The purpose of the device is to redirect all of the weight of a weapon to the soldier’s body and lessen the weight on the soldier’s arms, freeing up his or her hands for other tasks. The prototype of the third arm weighs less than four pounds thanks to the use of carbon fiber composites.

“We’re looking at a new way for the Soldier to interface with the weapon,” said Zac Wingard, a mechanical engineer for the Army Research Laboratory’s Weapons and Materials Research Directorate. “It is not a product; it is simply a way to study how far we can push the ballistic performance of future weapons without increasing Soldier burden.”

As the Army Research Laboratory explained, some soldiers are weighed down by combat gear heavier than 110 pounds. Those heavy loads may worsen as high energy weapons are developed for future warfare.

“You wind up pushing that Soldier’s combat load up beyond 120 pounds and they’re already overburdened,” Wingard said during the Association of the United States Army’s Global Force Symposium. “We have Soldiers in their late teens and early 20s and they’re getting broken sometimes in training before they see a day in combat.”

To test the device, researchers are conducting a test with a few Soldiers using the M4 carbine on a firing range at Aberdeen Proving Ground in Maryland. As part of the test, the soldiers wear special sensors on their arms and upper body to measure muscle activity to determine if there’s a change in fatigue when shooting with the device.  Researchers also score soldiers’ shots to see if there’s an improvement in marksmanship.

The third arm could also allow soldiers to use future weapons with more recoil. Additionally, researchers plan to examine the device’s potential applications for various fighting techniques, like shoot-on-the-move, close-quarters combat, or even shooting around corners with augmented reality displays.