Silencer

A suppressor, also known by the slang term silencer, is a device fixed on the end of a gun's barrel to reduce the weapon's perceptibility. In real life, suppressed weapons are generally still semi-loud, but they also bring advantages such as greatly reduced muzzle flash. Suppressors reduce the sound of gunfire by allowing the rapidly expanding gases from the firing of the bullet to be temporarily diverted or trapped in a series of hollow chambers, known as expansion chambers. The trapped gas expands and cools, and its pressure and velocity decrease as it exits the chambers. Suppressors can fire supersonic ammunition, but this wears out the suppressor very quickly, and is not as quiet as using subsonic ammunition.

Call of Duty: United Offensive
The first use of silencers 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 starts with. He can aquire weapons from dead German soldiers but the Silenced 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 Silenced Sten it returns for the next level. However, it is impossible to complete the mission with only the silenced 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, 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 your presence, they must either call a UAV or make a visual in order to locate you. Along with the reduced shot loudness, this makes it much more difficult to locate, and furthermore track, your 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 SMGs 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 SMGs 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 SMGs except the PPSh-41 can have suppressor attachments to them. Oddly, the Gewehr 43 with the suppressor attached 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 your exact position if you catch 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, pistols do not have suppressors and they cannot be unlocked.

Weapon Compatibility

 * Gewehr 43
 * Thompson
 * MP40
 * Type 100

Flash Hider
Flash Hiders are 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.

Interestingly enough, real flash hiders are actually intended to prevent the weapon's muzzle flash from obscuring the firer's view, and thus affecting their aim, when firing multiple shots. They do not make the flash any less visible to those downrange of the weapon.

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 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 silencer model. Silencers are unlocked via Marksman challenges.

Silencer-Radar glitch
In the Call of Duty: Modern Warfare 2 multiplayer mode, if the player puts a silencer on any of these weapons: The silencer will have no effect on the radar. In other terms, the user will show up on the radar with or without a silencer. However, the Stimulus Package update has patched this glitch.
 * M240
 * M9 (the m9 is still glitched)
 * MG4

Tips

 * When a Suppressor is attached to a weapon it also removes the flash produced when firing, making a player less visible to the naked eye when firing their weapon. This, in combination with a stealth class such as an SMG or Assault Rifle using Cold-Blooded and Ninja, can make a player using proper cover very difficult to pinpoint.
 * Suppressors are very effective in Hardcore modes because players have much less health. In Hardcore, most silenced weapons can still kill in one or two shots. Also, people who don't usually do hardcore game types may not notice that if someone shoots, without a suppressor, the enemy can simply press the pause button and view the map, seeing the red dots. This is used more in hardcore Search and Destroy, where the player has more time and reason to pause the game in a safe spot, tracking red dots on the radar.
 * While many people don't think that muzzle flash gives someone's position away, it's surprisingly obvious especially when firing out a window or on a night map.

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 game art featured in Official Xbox Magazine.