The United States Army believes it may have found the sweet spot for rifle ammunition caliber, but the specific round has never been tested on a battlefield by US forces, the Army Times reported Monday.

The army is looking for a round with the positive characteristics of the 7.62mm round's increased lethality and accuracy, but, ideally, is a little bit lighter, which allows a soldier to carry more rounds.

According to Army Lt. Col. Andrew Lunoff, a 6.8mm round is under consideration to become the preferred round for use in squad weapons. The Army has a requirement for its crew served weapons to produce a whole new cartridge, including the projectile or bullet per se as well as the casing around it.

"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 colonel told the Army Times.

The 6.8mm round is 10 percent lighter than the 7.62mm, which is fired by the iconic Kalashnikov AK-47.

The cartridge is modelled from a.30 Remington cartridge. The 6.8mm round is viewed by weapons experts as a midway compromise between the 5.56mm cartridge that's standard across M4 rifles and NATO rifles and the 7.62mm round.