The Barrett .50cal is almost completely unchanged from Call of Duty 4, with the exceptions of new attachments, a redesigned scope, widened muzzle brake, and lack of back up front iron sight. The only notable change from Call of Duty 4 is that the Barrett .50cal, along with all the other sniper rifles, now have full mobility, as well as SMGs. In addition, it is the first sniper rifle available to the player, while in Call of Duty 4 it is the last.
Single player[]
The Barrett .50cal can be found three times in the single player campaign. It is found in the missions, "Of Their Own Accord" (although it is mounted with a thermal scope and variable zoom), "Contingency" and "Loose Ends." In Special Ops it is found in "Sniper Fi", "Estate Takedown" and "Armor Piercing". The only major differences from campaign to multiplayer are that the Barrett has a more realistic level of recoil, and a fairly low Firecap in the campaign. The Barrett .50cal is a good weapon to use against juggernauts, as it takes 3 headshots, or 6 chest shots to kill one.
Multiplayer[]
In Multiplayer, the Barrett .50cal is unlocked at Level 3 as part of the "Scout Sniper" default class. It is capable of firing faster than its sight can settle. Firing too quickly makes the Barrett .50cal difficult to use, due to the high recoil. However, the Barrett .50cal does have a recoil limit. This problem is easily mitigated by simply slowing the rate of fire and only firing when the recoil has settled. This requires great concentration, as inexperienced players tend to fire too fast. However, the ability to fire so fast can be an advantage in close quarters when there is no time to switch to a secondary and the player is forced to fire their sniper rifle from the hip. The Barrett .50cal is most praised for its ability to deliver one hit kills with a high rate of fire.
With Stopping Power, the weapon kills in one hit to the head, neck, chest and stomach. Without it, it loses the one shot kill to the stomach. Targets will require multiple hits when Painkiller, Last Stand or Final Stand is used. However, headshots cancel out Last and Final Stand.
One flaw of the Barrett is that its recoil kicks the gun up and to the right so much that the shooter momentarily loses sight of their target. Since the ACOG scope zooms in less when looking down the sight, it is easier to follow an enemy after firing with it than with a standard Sniper Scope, but in many situations the decreased zoom and inability to steady the scope makes it less than practical.
The Barrett is a relatively good candidate to use with a Silencer and Stopping Power, as the player can kill a target with a single shot to the chest, neck, or head. However, the Barrett's high recoil can make it difficult for the shooter to land a second shot if the first shot does not kill. Without Stopping Power, the Barrett is a less than ideal candidate for a silencer because all sniper rifles require two shots to kill when using a silencer without Stopping Power unless on Hardcore.