Marines and Soldiers carry enough stuff already and welcome any chance to go lighter.

That even includes lighter ammo -- so long as the round remains as effective as what they're shooting now -- and to get there AAI Corp. is testing rounds without brass casings. One, which promises to be 35 percent lighter than the standard 5.56-mm bullet, has a polymer casing. The other, for all intents and purposes, does not have a casing -- the round is embedded in a high-temperature ignition propellant that, when fired, is vaporized.

It was last December the company picked up a three-year, $5.8 million contract from the Army's Joint Service Small Arms Program Office to continue work on its light-weight weapon and ammo. Total funding under the contract could reach $28 million, according to the company.

The contact calls for AAI to continue work on its 5.56-mm machine gun and two types of light-weight ammo -- the cased and caseless rounds the company had on display this week at Modern Day Marine at Quantico.

The goal of the Lightweight Small Arms Technologies program is to reduce the weight and size of the small arms and ammo used by Marines and Soldiers.

"We've got a polymer-cased ammunition," said David A. Phillips, vice president for Business Development and Advanced Systems at AAI. "It has a telescoped configuration and uses the same ball propellant as the standard 5.56-mm round."

The company is working specifically on 5.56-caliber, he said, but has been asked by the Marine Corps and the Army to work everything scalable to be 5.56- and the 7.62-caliber used by NATO.

The 5.56 round on display constituted about a 35 percent weight reduction from the standard brass-cased round, he said. The caseless round is about 50 percent lighter than the standard round, he said.

According to another of the AAI officials taking part at Modern Day Marine, Marines who stop by and learn they might eventually be toting ammo that's up to 50 percent lighter than what they use now have a typical response.

"Hey, now I can carry more ammo."

- Bryant Jordan