The XM9 Rifle is the US Army's replacement for the abandoned XM8 rifle. Like the XM8, it is a modular weapon with four variants: a baseline carbine, a compact carbine, a sharpshooter, and a heavy-barreled automatic. There is also an optional XM322 grenade launcher that can be attached to the main weapon. The XM9 is used several times in the EndWar novel. It fires the standard 5.56x45mm NATO round used by the M16.
This contradicts the existence of the 6.8mm SCAR A1 as the new US Joint Strike Force service rifle. The XM9 was abandoned by the game's developers, who felt the XM8 had been "overused" in becoming the staple next-gen American rifle in fiction.
In the EndWar novel, Master Sgt. McAllen uses an XM9 with an XM322 underbarrel grenade launcher.
- The real life XM8 was turned down by the US Army for its high cost, bare minimum improvement over the M16A4 and the ineffectiveness of variants when compared with purpose-designed weapons in the same class.