M40A3

The M40A3 is a variant of the M40 bolt-action sniper rifle used by the United States Marine Corps. The M40 was introduced in 1966. The Marine Corps' transition to the M40A1 model was completed in the 1970s, and later adopted the M40A3 in 2001. The A3 model costs $3,200. Each M40 is a Remington Model 700 modified by USMC gunsmiths. As new M40A3s are built, M40A1s are upgraded to M40A3s when they are enter the armories for maintenance and repair.

The original M40 was a military type-classified version of the Model 700; it was factory-made, and had a one-piece wooden stock. The M40A1 and M40A3 switched to fiberglass, with new scopes added as well. The scope itself, the Schmidt & Bender 3–12 x 50 PM II Military, costs $1,000.

Call of Duty 4
The M40A3 is only available in Multiplayer. It is the first sniper rifle to be unlocked at rank 3, and is a favorite among the experienced and inexperienced alike. It is the most accurate of the sniper rifles. As with all sniper rifles, it is best used at long range, where it can be used to provide covering fire for allies.

The M40A3 is one of two bolt-action sniper rifles, the other one being the R700. It has low recoil, so it is easy to track your target if the first shot missed/did not kill the target. It has a 5 round magazine that is loaded one round at a time. The M40A3 has one huge disadvantage that other sniper rifles do not have: it is comparatively difficult to use without Stopping Power. Without Stopping Power, the M40A3 is a one-shot kill only to the head and neck, and its rate of fire is too low to reliably two-shot kill. This means that Stopping Power is practically a necessity. This also means that the M40A3 is less than ideal for killing Juggernauts even when it has Stopping Power equipped, as Juggernaut cancels out Stopping Power. However, with Stopping Power, the M40A3 is just as powerful as the R700 and Barrett .50 Cal against non-Juggernauts. That is the reason why it is so popular among players.

The M40A3 has one unique feature not seen with any other weapon. When it is equipped with the ACOG, its base damage is raised from 70 to 75. This means that, when combined with stopping power, it is a one-shot-kill anywhere on a non-Juggernaut, and is still a one-shot-kill on Juggernauts when the round impacts on the neck or head. It also makes it easier to use the M40A3 at closer ranges and facilitates quick-scoping, due to the ACOG's reduced magnification and aiming time compared to the rifle scope, respectively.

Overall, the M40A3 is a great sniper rifle to get accustomed to, and a great sniper rifle even at the later ranks.

Call of Duty 4 DS
The DS version is similar to the console version. It does a very high amount of damage, and the reloading process takes a while. The M40 in the DS version is black instead of green, has more recoil, and a lower rate of fire.

Trivia

 * The M40A3 in Call of Duty 4 uses the Unertl MST-100 10× fixed day scope, but the windage adjustment is on the wrong side. But the scope could be for a left-handed shooter.
 * Because the M40A3's default color is green, Digital Camouflage can be used as an alternative to Woodland Camouflage in grassy environments.
 * The M40A3 is seen as the favorite choice for "no-scope" snipers.