Silencer

The Suppressor 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: Black Ops. They prevent gunfire from showing up on enemy minimaps and make it harder to hear, but as a disadvantage, the suppressor 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.

Call of Duty: United Offensive
The first use of suppressors in the Call of Duty franchise was 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 Germans. Ironically all of the fire from the German weapons doesn't alert any of the others. 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
In Call of Duty 4: Modern Warfare, suppressors can be used on pistols (except the Desert Eagle), assault rifles, or submachine guns. When a player fires a weapon without a suppressor, 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 suppressor also reduces shot loudness, muzzle flash, and effective bullet range. 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 players 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 players movements.

The major disadvantage of the suppressor 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 (or 1000 inch) 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 suppressors 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 suppressor 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 suppressor, 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 suppressor + UAV Jammer class can easily sow chaos in the rear lines of the enemy ranks. Attaching a suppressor without the UAV Jammer is more risky than choosing a UAV Jammer without a suppressor, as if an enemy player acquires UAV Recon, the player using the suppressor will suddenly be revealed, taking the stealth effect provided by the suppressor 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 suppressor 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 suppressor attachment is unlocked at 75 kills (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 receives no attachments.

In singleplayer, it is 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.

Call of Duty: World at War
Working in the same fashion as their Call of Duty 4: Modern Warfare counterparts, the Gewehr 43, and all submachine guns except the PPSh-41 can have suppressor attachments to them. Oddly, the Gewehr 43 with the suppressor attachment will have the same reload animation for mid-magazine reloading as empty magazine reloading. The reload at partial magazine is hastened so that it takes the same amount of time as a normal mid-mag reload, but if the entire magazine is spent it will reload as slow as it normally would. Enemies will have difficultly finding he player's exact position if he catches him off guard. Missed shots are also less detrimental with the suppressor, as the enemy will have more difficulty telling where the shots came from, however they will still hear the crack of the bullets flying past them and see the tracer shots.

Unlike Call of Duty 4: Modern Warfare, pistols do not have suppressors and they cannot be unlocked.

Weapon Compatibility

 * Gewehr 43
 * Thompson
 * MP40
 * Type 100

Flash Hider
Flash Hiders are a different type of suppressor, found in Call of Duty: World at War. They are available for all non-bolt action rifles in the game, excluding the Gewehr 43, which has a Suppressor instead. It is unlocked for a weapon after completing that weapon's Marksman I challenge.

The flash hider greatly reduces muzzle flash, and makes the shooter invisible on radar, meaning it is effective for stealth classes. It does, however reduce range, which can make rifles less effective in sharpshooting (much to the same effect of a suppressor). However, it doesn't dampen the sound of the shot, so the shots will still be just as loud as usual.

Certain machine guns in World at War are pre-equipped with flash hiders, like the Type 99, MG-42, and DP-28, but they do nothing like the 'attachment' flash hiders and do not affect gameplay.

Weapon Compatibility

 * SVT-40
 * M1 Garand
 * STG-44
 * M1A1 Carbine

Call of Duty: Modern Warfare 2
Suppressors return in Call of Duty: Modern Warfare 2 as an attachment for submachine guns, pistols, assault rifles, shotguns, sniper rifles, light machine guns, and machine pistols. Launchers, Riot Shields, higher caliber pistols, and akimbo-capable shotguns are the only weapons that cannot accept suppressors. Submachine guns, pistols, and machine pistols suffer the least from equipping a suppressor, 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. Suppressors 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 a suppressed sniper rifle. Suppressors also reduce base damage values by 10 points on Light Machine Guns. Shotguns suffer an extreme reduction in range when using suppressors, 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 suppressor. When combined with the perks Cold-Blooded and the pro version of Ninja, the suppressor 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 suppressor. Strangely, all of the weapons seem to use the same suppressor model. Suppressors are unlocked via Marksman challenges.

Silencer-Radar glitch
Using a suppressor on these weapons in any version of Call of Duty: Modern Warfare 2 did not prevent the firer from showing up on enemy radar:

However, these glitches have been fixed on the Xbox 360 version of the game with the release of the Stimulus Package.
 * M240
 * M9
 * MG4

Call of Duty: Black Ops
Suppressors will return to the newest installment of the series, Call of Duty: Black Ops. In the teaser trailer for the game, a Suppressor is seen on an AUG. Another one is seen attached to a MAC-10. In a multiplayer teaser trailer, it was seen on the Commando (the Red Dot Sight was also on it) and a pickup icon for an "MP5K Suppressor" was shown.

Trivia

 * Flash hiders, in reality, are meant to prevent the muzzle flash from blocking the user's vision.
 * The name "silencer" is actually incorrect and is actually "suppressor" because it doesn't completely silence the sound of weapons firing.