The M40 is a sniper rifle used by the United States Marine Corps. It has had three variants â€” the M40, the M40A1 and the M40A3. The M40 was introduced in 1966. The changeover to the A1 model was completed in the 1970s, and the A3 in the 2000s. The A3 model costs $3,200.

Each weapon begins life as a Remington 700, and is then extensively modified by hand by USMC armorers at Marine Corps Base Quantico, using components from a number of suppliers. New M40A3s are being built, and A1s are upgraded to A3s as they rotate into the armory for service and repair. The rifles have had many sub-variations in telescopic sights, and smaller user modifications.

The original M40 was a military type-classified version of the Remington 700; it was factory-made, and had a one-piece wooden stock. The M40A1 and A3 switched to fiberglass, with new scopes added as well. The scope itself costs $1000.

During the Vietnam War, the Marine Corps decided they needed a standard sniper rifle. After testing several possibilities, they ordered 700 Remington Model 40x rifles (target/varmint version of the Model 700 bolt-action rifle), and gave them the M40 designation. Most had a Redfield [1] 3â€“9 power Accurange variable scope mounted. With time, certain weaknesses, primarily warping of the all-wood stock, became apparent. Sometime in the early 1970s, the USMC armorers at MCB Quantico began rebuilding the original M40s into M40A1s. The process involved, among other improvements, replacing the original wood stocks with McMillan A1[2] fiberglass stocks, as well as replacing the original Redfield scopes with Unertl [3] scopes.

M40A3

In 1996 the USMC started on the design for the replacement of the M40A1, the result was the M40A3. It uses a Remington 700 short action, with a steel floorplate assembly and trigger guard built by D.D. Ross. The Unertl rings and bases have been replaced with D.D. Ross base and BADGER ORDNANCE Machine rings. The rifles also come with a Harris bipod and an accessory rail, built by G&G Machine. The stock is a new McMillan A4, with adjustable cheek and length of pull.

As the M40A1's rotate in for service and repair, they are replaced by M40A3's. All M40A3s are built by USMC Armorers at Quantico Virginia. The M40A3 is an outstanding replacement for the aging M40A1's. The rifles are extremely accurate, very rugged, and are designed from the ground up to be a superb sniper rifle. Combined with the new M118LR ammo, it makes a system that is ranked with the best in the world.