The things they carry: weapons experts working to lighten troops' small arms load.

• Author: Jean, Grace V.
• Position: Technology

Efforts to lighten soldiers' loads have focused on reducing the weight of body armor and shrinking the size of batteries and other equipment that they carry into combat. But for machine gunners, the bulk of the weight--about 40 pounds--is in the weapon and ammunition that they lug.

Technologists are working to cut small arms weight in half without compromising firepower, and so far prototypes of a redesigned machine gun and ammunition are demonstrating the art of the possible. Engineers are applying those lessons to build a lighter assault rifle that would help decrease the average soldier's combat load, too.

"We've really proved the feasibility of reducing the weight," says Kori Phillips, project management engineer for the joint service small arms program office at the Army's Armament Research, Development and Engineering Center at Picatinny Arsenal in New Jersey.

A team of contractors led by AM Corp. has developed a weapon system that reduces by 43 percent a soldier's combat load. "That's a big deal to a guy carrying this stuff up in the mountains of Afghanistan," Phillips says.

Using the M249 squad automatic weapon and the M855 5.56mm ammunition as baseline references, the team was able to develop prototypes that reduce the weight of the machine gun by 45 percent and the weight of ammunition by as much as 50 percent.

Unlike previous efforts to lighten the load by substituting metal components in existing weapons with different materials, the team has taken a "dean-slate" approach in developing the new technologies from scratch. The only requirements were that engineers had to design the weapon around the existing 5.56mm bullet while also preserving the muzzle velocity, lethality and accuracy of existing firearms and maintaining similar price points for affordability.

"We've basically redesigned the weapon and the amino together so that we could address those issues," says AAI's Paul Shipley, program manager for the lightweight small arms technologies program. "That's the breakthrough, in that you have to treat it as an entire weapon system."

To make the ammunition lighter, engineers honed in on the bullet and redesigned the cartridge so that it incorporated polymers. The revision yielded two technolo gies: a cased telescoped ammunition round, which resembles an old-fashioned spyglass folded up; and a caseless telescoped ammunition round.

In the cased ammunition variant, a plastic shell arrangement replaces the traditional brass found in...