Five units will soon deploy with the new M27 infantry automatic rifle, a 5.56mm weapon that may one day replace the M249 squad automatic weapon. A total of 458 rifles will be delivered by the gun’s maker, Heckler and Koch, and meted out to five battalions working up for deployments to Afghanistan.
The 5.56mm weapon that might replace the M249 squad automatic weapon, depending on its initial effectiveness for an initial five battalions in Afghanistan. It's made by Hecker and Koch.
More details @ Marine Corps Times