Silencer

The Silencer is a weapon attachment available in Call of Duty: United Offensive, Call of Duty 4: Modern Warfare, Call of Duty: World at War, Call of Duty: Modern Warfare 2, and Call of Duty: Modern Warfare 3. This attachment prevents gunfire from showing up on enemy minimaps and makes it harder to hear and locate the position of the shooter. It also somewhat reduces the muzzle flash of the weapon. As a disadvantage, the Silencer either reduces the range at which weapons do their maximum damage, reduces damage of the weapon as a whole, or decreases the damage done by the weapon at its longest range depending on what weapon the silencer is used with. Due to its low accuracy you'll have to get closer to get a kill.

Call of Duty: United Offensive
The first use of silencers in the Call of Duty franchise were in the Sicily levels of Call of Duty: United Offensive. A suppressed Sten was the only default weapon Sgt. Doyle started with. He can acquire weapons from dead German soldiers but the suppressed Sten is given so the player can get up to the fortifications without alerting any enemies present. Ironically, all fire from the German weapons do not alert any of the enemies, even though these arms do not use silencers.

If the player ends the first Sicily level with the suppressed Sten, it returns for the next level. However, it is impossible to complete the mission with only the suppressed Sten as the player cannot use the ammo from the MP40s, even though it is the same type. However, it can be kept as a secondary weapon, using any captured German gun as a primary.

Call of Duty 4: Modern Warfare
"Invisible on GPS when firing, reduced muzzle flash, but shorter range."

- Attachment description

Campaign
Silencers are attached to the USP .45 in "All Ghillied Up", "One Shot, One Kill", "Ultimatum", "All In", "No Fighting In The War Room", and "Mile High Club", the MP5 in "Crew Expendable", "Ultimatum" and "Mile High Club", the M4A1 SOPMOD in a majority of MacTavish's missions, the M21 in "Blackout" and "All Ghillied Up", and the P90 in "All Ghillied Up". In stealth-based missions, such as "All Ghillied Up" and the start of "Blackout", the silencer is necessary in order to kill with the player's gun. If using an unsilenced weapon, the enemies will be alerted, and at most, can lead to the player's failure of the mission.

Multiplayer
Silencers can be used on all pistols except the Desert Eagle, assault rifles except the MP44, and submachine guns. When a player fires a weapon without a silencer, they will temporarily appear as a red dot on the mini map to enemy players. Firing a suppressed weapon will not cause the player to appear on the mini map in this fashion. The silencer also reduces shot volume and muzzle flash. Note that a suppressed weapon grants no amnesty from the UAV Recon.

The "invisibility" afforded by the mini-map is invaluable for flanking or ambushing. Even when enemies are alerted to the player's presence, they must either call a UAV or make a visual in order to locate the player. Along with the reduced shot loudness, this makes it much more difficult to locate, and furthermore track, the player's movements.

The major disadvantage of the silencer is the reduction in damage over range. Damage over range is reduced to about 70% of its original value for submachine guns and pistols, and to less than 50% for assault rifles. It should be noted that at a 25m range and beyond, bullets from a suppressed assault rifle will be dealing their minimum damage, while an unsuppressed assault rifle will still be dealing maximum bullet damage. This emphasizes the use of silencers as a close to mid-range attachment.

Despite the range penalty, powerful and loud weapons such as the AK-47 or the M14 can become somewhat more manageable with a silencer in certain situations. Such weapons are often plagued with being a combat magnet from the range at which they can be heard firing. With a silencer, they become particularly devastating at mid range due to the stealth and sheer power.

As the only thing which can reveal a player on the radar while using suppressed weapons is a UAV, the UAV Jammer Perk is an obvious choice for those wishing to take the pure stealth option. A silencer + UAV Jammer class can easily cause chaos in the rear lines of the enemy ranks. Attaching a silencer without the UAV Jammer is more risky than choosing a UAV Jammer without a silencer, as if an enemy player acquires UAV Recon, the player using the silencer will suddenly be revealed, taking the stealth effect provided by the silencer away. Therefore, on larger matches, it's preferable to either take both or just the UAV Jammer, as a well-timed ambush can kill many enemies in a short space of time, negating the need for a silencer as the impending threat of the enemies is removed. As an alternative, a suppressed pistol can be used, acquiring kills without alerting the enemy team of the user's location.

Flanking the enemy may also be an effective technique, achieved by use of Extreme Conditioning. Dead Silence may also be an effective choice, particularly in Search and Destroy, where players often tend to listen carefully for enemy footsteps.

The Silencer attachment is unlocked for completing Marksman II for submachine guns and assault rifles. The attachment is automatically unlocked for pistols when the pistol itself is unlocked, excluding the Desert Eagle, which cannot accept a silencer.

Call of Duty: Modern Warfare 2
Silencers return in Call of Duty: Modern Warfare 2 as an attachment for Submachine Guns, Handguns, Assault Rifles, Shotguns, Sniper Rifles, Light Machine Guns, and Machine Pistols. Only launchers, the Riot Shield, high caliber pistols (.44 Magnum and Desert Eagle) and Akimbo-capable Shotguns (Ranger and Model 1887) cannot accept silencers.

SMGs, Pistols, and Machine Pistols suffer the least from equipping a silencer, as there is only a slight reduction in range with no reduction in base damage. Assault rifles suffer a considerable range reduction, but do not suffer a reduction in base damage. Silencers reduce Sniper Rifle base damage values from 70 to 50. Without Stopping Power, it will always require at least two shots to kill an enemy with any suppressed sniper rifle. Silencers also reduce base damage values by 10 points on Light Machine Guns. Shotguns suffer an extreme reduction in range when using silencers, and are considered unusable by most players. The one exception to this is the Striker, which suffers much less of a range reduction than other shotguns when equipped with a silencer. When combined with the perks Cold-Blooded and the pro version of Ninja, the silencer makes a player completely invisible to all forms of detection other than being seen or making noise by doing things like falling, switching weapons, defusing a bomb, activating a killstreak, or shooting, although shooting is obviously much less noticeable when using a silencer. Special consideration should be given to Killcam when operating such a class; precautions such staying in ADS for a few seconds after a kill can be essential in disguising the player's position. Strangely, all of the weapons seem to use the same silencer model. Using a silencer on these weapons in any version of Call of Duty: Modern Warfare 2 does not prevent the shooter from showing up on enemy radar:
 * M240
 * M9
 * MG4

Call of Duty: Modern Warfare 3
"Invisible on radar when firing."

- Attachment description

The silencer makes a return in Call of Duty: Modern Warfare 3 and was first spotted in the first reveal trailer being sported by several MP5 submachine guns.

Campaign and Special Ops
It can be seen on some AK-47s, with or without the ACOG Scope or Grenade Launcher. The silencer can also be found on other weapons in the campaign, as well as weapons that the player start off with. It can be found on starting weapons in missions such as Mind the Gap and Eye of the Storm.

The silencer is also found in Special Ops, but only in mission mode. There is basically no difference in gameplay with the attachment when in campaign or Special Ops. The silencer can be found in missions such as Resistance Movement and Invisible Threat.

Multiplayer
In multiplayer, it can be used on nearly all the weapons with exceptions being Launchers and certain pistols. It is unlocked at Weapon Proficiency Level 2 for Pistols and Machine Pistols, and Weapon Proficiency Level 5 for every other weapon. It behaves similarly to the previous variants, making the player not appear in the mini-map when firing, as well as dampening the muzzle flash and sound, but reducing the effective range of the weapon. The silencer, whilst also reducing the speed at which the round moves, also reduces the damage that each round can deal. Significant differences can be seen in weapons such as the MSR, going from one shot to two, and other assault rifles, especially low range and low damage variants.

Trivia

 * In Modern Warfare 3, often the same weapon when silenced has a different firing sound in Singleplayer than in Multiplayer.