Pvt. Michael Rojas fires an M249 light machine gun during small arms training in Arta, Djibouti. The Army is looking to replace the M249 light machine gun he is using with what it is calling the Next Generation Squad Automatic Rifle.

The U.S. Army has plans for a new squad automatic rifle, and it’s going to fire ammunition that uses a casings and bullets that have never been used on the battlefield.

According to this story from armytimes.com, Army Lt. Col. Andrew Lunoff, product manager for the branch’s small caliber ammunition program, said that the round currently under consideration is a 6.8mm round.

He says its the offspring of a project formally known as the Enhanced Rifle Cartridge Program that combined Special Operations Command, the Army Marksmanship Unit, and Remington Arms to create an alternative to the 5.56mm round currently in use.

The 6.8mm falls in the sweet spot that the Army is looking for—with all the positive aspects of the 7.62mm NATO round, but with more lethality and accuracy. The new ammo also saves about 10 percent in weight—an important consideration for a combat load.

But, as usual, the Army reserves the right to change its mind. From the story:

“But work doesn’t end with the projectile, which hasn’t been officially named as the caliber but is the basis for much of current testing.” “Lt. Col. Loyd Beal III, product manager for the Army’s crew served weapons program, said the requirements to lighten the load will mean not just a new projectile for increased lethality, but a new case to carry that bullet.”

“‘The requirement is going to drive us to a new type of ammunition,” Beal said. “It’s going to have to be lighter. You can’t just go out and get a brass type, which pushes us to a polymer or some type of steel or something I don’t even know about yet.’”

The development of this new intermediate-caliber ammo is happening in tandem with the Army’s plan to make a replacement for the Squad Automatic Weapon, known as the Next Generation Squad Automatic Rifle, the story says.

The story says the NGSAR program will inform not only a new machine gun, but will soon follow with a new carbine for individual soldiers.

Prototypes for the NGSAR program are expected to be ready for testing by late next year or early 2020, with the rifle being field tested by 2021.