Extended Mags

= Call of Duty: World at War = The Large Magazine is an attachment available for the MP40, Thompson, Type 100, M1 Carbine, and the PPSh-41 in Call of Duty: World at War multiplayer. The attachment doubles the ammunition capacity of a given weapon.

The exact name depends on the weapon, for the Thompson and the PPSh-41, it is called Round Drum, for the MP40 it is Dual Magazines, and for the Type 100 and the M1 Carbine it is called Box Magazine (though strangely if you have not unlocked the Box Magazine for the Type 100, the Marksman challenge will describe it as an "Extended Clip" instead).

Whatever the name, the attachment is unlocked when the Marksman III, or for the M1 Carbine, the Marksman IV, challenge is completed, or for the PPSh-41, when the Marksman II challenge is completed.

Multiplayer Tactics
What makes the extended magazines effective for SMGs is that it decreases the likelihood of being caught reloading. Having Bandolier further increases the ammo storage. It is often used in conjunction with the Thompson for its low 20-bullet magazine, and for the PPSh-41 as the small magazine will be eaten up too fast by the gun's extremely high rate of fire. Also, MP40 users can use round drums to spray-and-pray, since the drum gives them half a minute of supressing fire. This attachment allows SMGs to constantly fire on a target; often the user will "spray and pray" in a battle since they have more bullets to spend and less frequent reloading to do, which is a tactic that is frowned upon by more experienced players.

This attachment can greatly increase its user's ability to remain mobile and engage numerous targets. It is extremely useful for rushers. The larger ammo capacity is also invaluable to players using Double Tap, as the extreme fire rates would quickly diminish the standard magazines; it is very common to see double-tappers using extended magazines.

= Call of Duty: Modern Warfare 2 =

A similar attachment exists in Call of Duty: Modern Warfare 2. It is unlocked by getting 40 bullet penetration kills while using Full Metal Jacket rounds, or it is obtained by getting the last marksman challenge for a sidearm or shotgun. It is compatible with all guns in the game except for: the launchers, Desert Eagle, .44 Magnum, Ranger and the Model 1887. The amount of ammo in a magazine that it increases is dependent on the gun. Generally, It increases magazine size by 50%, but with some guns it can double the magazine size of a gun (such as the RPD and AA-12),

Obtaining

 * An easy way to attain the Extended Magazines in Modern Warfare 2 is to crouch behind thin cover (i.e. cubicles, drums, etc) in the 3rd person game-type and then spray them with hip-fire, as you can see over the cover.
 * Alternatively, Highrise is a good map for getting penetration kills, as opponents' heads are often visible above cubicles but their bodies can be shot through thin cubicle walls.
 * Alternatively, on Terminal you can hide behind the counter at the check-in, then shoot people who exit the place through the counter that is located mid-way between the two points. This is only advisable in Hardcore mode.
 * Favela is also filled with thin walls that are easy to penetrate with the FMJ attachment.
 * Sniper rifles by far are the easiest to get the extended magazine on as they can get a 1 shot kill through glass which counts towards the penetration kills that the gun needs. Also, collateral damage kills do appear to count as "penetration" kills, another reason for the ease of getting extended mags with a sniper.
 * However, some cover, such as walls, are thicker than others, like sheet metal, and some sniper shots don't get a one hit kill, and makes the target get to better cover. This makes it easier for other weapons as automatic fire makes it harder for the opponent to escape.

Tactics
The Extended magazines are used best with guns with small magazines to start out with and guns with a high rate of fire, and is recommended to use with Bling unless you like the iron sights of the weapon.

Trivia

 * Although Extended Magazines increase the capacity of your magazine, it doesn't increase your starting ammo count. For example, if starting with the SCAR-H, you have one 20 round magazine in your gun and two spares. With Extended Magazines (and without Scavenger Pro), you start off with one 30-rd magazine in your gun and only one spare (Both loadouts starting with 60 bullets each). With the RPD and Extended Magazine all of the player's ammo is loaded into one very large magazine.
 * The Extended Magazine attachment has no cosmetic effect on the magazine.
 * Unlike in World at War, in Modern Warfare 2 having an extended mag does not increase reload time.