M39 Enhanced Marksman Rifle

In November 1992, Marine Corps Systems Command drafted a mission needs statement for an enhanced sniper support team weapon (SSTW). The requirement called for a weapon to support the M40A1 sniper rifle within Scout Sniper teams during close-range engagements and to deliver rapid semi-automatic suppressive fire. The role was then filled by the M16A2, which could not mount optics or night vision sights and fired M855 5.56×45mm NATO ammunition considered too inaccurate for the task. The enhanced SSTW was required to engage targets out to 600 metres, use ammunition interchangeable with the M40A1, accept a sound suppressor and optics, and remain supportable within the Fleet Marine Forces logistics system. An earlier designated marksman effort had adapted the M14, but the resulting weapon was less accurate than bolt-action rifles and did not fit the existing logistics arrangements. Rifle builders continued refining the design and produced successive versions described as interim measures; these eventually became a programme in their own right and culminated in the M39 Enhanced Marksman Rifle. The rifle is manufactured by Sage International and maintained by the USMC Precision Weapons Section.

The M39 is a semi-automatic, gas-operated designated marksman rifle chambered for the 7.62×51mm NATO cartridge, built as a modified and accurized M14 and comparable to the Mk 14 Enhanced Battle Rifle. It derives from the Marine Corps Designated Marksman Rifle (DMR) and differs from it in several respects. The metal stock is adjustable for length and comb height to provide a more consistent cheek weld, and the pistol grip is reshaped. A Picatinny rail accepts any rail-compatible optic, including a range of military scopes and imaging devices; the M8541 Scout Sniper Day Scope, originally developed for the M40A3, is issued with the rifle as a set. Where the DMR used a Harris S-L bipod, the EMR uses a modified version intended to be more durable. The rifle is issued with match-grade M118LR 175-grain long-range ammunition.

The EMR is issued primarily to designated marksmen, providing precision fire for units that do not have scout snipers assigned. Replacing the DMR, it gives such units an accurate weapon firing a cartridge more powerful than the 5.56×45mm NATO round of the M16A4. Marine scout snipers also employ the rifle on missions requiring rapid accurate fire, as do Marine Corps explosive ordnance disposal teams. In early 2012, the Marine Corps began replacing the M39 on a one-for-one basis with the M110 Semi-Automatic Sniper System, originally developed for the U.S. Army and designated Mk 11 Mod 2 in Marine Corps service. The M110 was assessed as meeting the SSTW requirement more closely, being able to mount suppressors and night vision systems while retaining zero, and offering training and supply commonality with the M16.