The M40 is a bolt-action sniper rifle used by the USMC. It has had four variants — the M40, M40A1, M40A3, and M40A5. The M40 was introduced in 1966. The changeover to the A1 model was completed in the 1970s, the A3 in the 2000s, and the A5 in 2009.
Each M40 is built from a Remington 700 bolt-action rifle, and is modified by USMC 2112 (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 M40A5 will incorporate a detachable magazine and a threaded barrel to allow for the use of a sound suppressor or other muzzle device.
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 stocks made by McMillan, with new scopes.The trigger pull on both models (M40A1/A3) is 3 to 5 lb (2.3 kg).