M40A3

About the M40A3

The M40A3 is the third generation of the USMC's M40 sniper rifle series, developed from 1996 to 2001 and placed into service during Operation Enduring Freedom. Built on the Remington Model 700 short-action receiver, the M40A3 represented a significant modernization over the M40A1, featuring a McMillan A4 fiberglass stock with adjustable cheekpiece and spacers for customized length of pull, a 24-inch Schneider match-grade heavy stainless steel barrel, and a Picatinny rail for optics mounting. The rifle retained the proven 5-round internal box magazine and bolt-action operation that defined the M40 series. Like all M40 variants, each rifle was individually hand-built by USMC armorers at the Precision Weapons Section, Marine Corps Base Quantico, maintaining the tradition of custom-built sniper rifles that began with the original M40 in 1966.

The M40A3 saw its combat baptism during the opening stages of Operation Enduring Freedom in Afghanistan in 2001, and went on to serve through some of the most intense urban and desert combat of the Iraq War. USMC Scout Snipers armed with M40A3 rifles played a critical role during the Second Battle of Fallujah in 2004, where sniper teams provided overwatch during house-to-house clearing operations. The transition from the Unertl 10x fixed scope to the Schmidt & Bender variable-power scope gave Marine snipers significantly more versatility in close-quarters and long-range engagements.

M40A3 specifications

Development of the M40A3 began in 1996 under the direction of the Marine Corps Scout Sniper School and the Precision Weapons Section at Quantico. The primary improvements over the M40A1 were the McMillan A4 stock with adjustable cheekpiece (replacing the A1 stock), the Schneider match-grade barrel (replacing the Atkinson/Hart barrel), and the addition of a Picatinny rail (replacing the Unertl-specific scope mount). The standard optic was the Schmidt & Bender 3-12x50 PM II LP scope, replacing the Unertl 10x fixed-power scope that had served since the M40A1. The M40A3 served through the heaviest fighting in Iraq and Afghanistan before being replaced by the M40A5 beginning in 2009.