Staff Writer (Updated: 4/15/2016):
With its origin in check, the newer M39 shares much of the same qualities of the M14 before it including its gas-operated, semi-automatic firing action as well as being chambered for the 7.62x51mm NATO standard cartridge. The M39 is, in essence, a further evolution of the M14 series itself, extending the operational life of the decades-old platform for the requirements of the new battlefield. The designator of "Enhanced Marksman Rifle" indicates its primary use by "non-sniper" elements, operators more akin to the "designated marksman" in the US military (also known as "sharpshooters" elsewhere) - a battlefield element tied to a long range, repeat-fire weapon intended to serve as an integrated part of the infantry squad. The M39 EMR was developed for use by the United States Marine Corps (USMC) and replaced the M14 Designated Marksman Rifle (M14 DMR) in the same role beginning in 2008. The M14 DMR itself served from 2001 to 2010 and saw combat action in the 2001 American invasion of Afghanistan and the 2003 American invasion of Iraq.
The designated marksman role falls upon an operator to provide accurized ranged repeat firepower at the squad level. This differs from the traditional dedicated sniper element for the DM is not officially rated a sniper per se ("Scout Sniper" in USMC nomenclature). As such, the designated marksman is provided slightly different tools for the role - a weapon developed more to fill the void within the squad that is already stocked with automatic assault rifles and squad assault weapons (SAW). In the case of the M39 EMR, the DM is given a proven combat rifle firing a full-power rifle cartridge - a quality the American assault rifle lacks (this being chambered for the 5.56mm cartridge). Optics allow for the precision required of long-range engagement.