Direct proof of use
U.S. Army and DVIDS sources document M14-family rifles in U.S. hands during the 2003 Iraq War. A Combat Studies Institute account of fighting in Hawijah on 7 April 2004 describes a U.S. sniper engaging an RPG gunner with an M14 sniper rifle from the roof of a municipal building.
DVIDS reporting from Forward Operating Base Speicher, near Tikrit, said the 4-101 Pathfinders were using M14 rifles in Iraq as medium-range weapons, with one soldier carrying a sniper-mission version. DVIDS imagery from Diyala province in December 2007 separately identifies a 4th Stryker Brigade Combat Team sniper providing security with an M14 Sniper Rifle during Operation Able Nightrain.
Sources: Between the Rivers, The M-14, Operation Able Nightrain M14
Timeline
The clearest dated combat-use account is Hawijah on 7 April 2004, where the M14 appears as a sniper rifle in an urban fight involving U.S. forces and Iraqi insurgents.
By late 2005, DVIDS described the M14 as a medium-range weapon in the 4-101 Pathfinders' arsenal in Iraq. In December 2007, DVIDS photographed an M14 sniper rifle in a security role during a Diyala clearing operation.
Sources: Between the Rivers, The M-14, Operation Able Nightrain M14
Role in Iraq
The Iraq evidence points to a limited, specialist role rather than general service-rifle issue. The documented uses center on a 7.62 mm rifle filling gaps between standard infantry carbines or rifles and heavier crew-served weapons: rooftop sniper engagement, medium-range coverage, and security overwatch during clearing operations.
The sources identify U.S. Army users, including the 4-101 Pathfinders and a sniper from Headquarters and Headquarters Company, 4th Battalion, 9th Infantry Regiment, 4th Stryker Brigade Combat Team, 2nd Infantry Division. The available sources do not establish Iraqi government or insurgent M14 use in this conflict entry.
Sources: The M-14, Operation Able Nightrain M14, Between the Rivers