The M40 is a bolt action sniper rifle used by the US Marines. It has four variants: the M40, the M40A1 , the M40A3 and the M40A5. It was introduced in 1966. The change to the A1 model was completed in the 1970s, the A3 and A5 in 2000 in 2009.
Each M40 is built around a Remington 700 hunting rifle, which is modified by the USMC 2112 unit of the Quantico Marine Corps Base, using parts supplied by various suppliers. New M40A3 rifles are being built, while A1s are upgraded to A3 standard because they enter and leave the arsenal for maintenance and repairs. The M40A5 will incorporate a removable charger and a threaded barrel to allow the use of a muffler or other device that mates in the muzzle.
The original M40 was a military version of the Remington 700; Was produced in series and had a stock of solid wood. The M40A1 and A3 went on to have fiberglass culverts made by McMillan, as well as new telescopic sights. The trigger in both models (M40A1 and A3) is adjustable from 1.36 to 2.26 kg (3-5 lb).