The first use of silencers in the Call of Duty franchise were in the Sicily levels of Call of Duty: United Offensive. A silenced Sten was the only default weapon Sgt. Doyle started with. He can acquire weapons from dead German soldiers, but the silenced 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 their 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 very difficult to complete the mission with only the silenced Sten as the player cannot use the ammo from the MP40s, even though they share the same ammo magazines. However, it can be kept as a secondary weapon, using any captured German gun as a primary.
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 JammerPerk is an obvious choice for those who wish to take the pure stealth option. A silencer with a 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 is 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.
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.
Working in the same fashion as their Call of Duty 4: Modern Warfare counterparts, the suppressor can be attached to the Gewehr 43 and all submachine guns except the PPSh-41. All the other rifles can attach a Flash Hider, which performs similarly to the suppressor. 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 mid-magazine is hastened so that it takes the same amount of time as a normal mid-magazine reload, but if the entire magazine is spent, it will reload as slow as it normally would. Enemies will have difficulty finding the 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.
Submachine Guns, 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, so this attachment is highly recommended. 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 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 penalty than other shotguns when equipped with a silencer.
Due to a glitch, the silencer does not properly work on MG4, M240 and M9, as firing will still result in radar detection. However, it still affects noise and muzzle flash, but given it reduces the damage for MG4 and M240 and range for M9, its usage is questionable.
The suppressor appears on the AUG and the M1911 (if switched, before being replaced by the Crossbow later on) in the mission "WMD". It also appears on an FAL and a Skorpion in the mission "Operation 40", as well as being used by Carlos on his M16 when on the plane.
The Suppressor affects the range of weapons with this attachment rather than the damage, except for the SPAS-12, which has no downsides to having a Suppressor attached as its range and damage are not reduced. In addition, sniper rifles get their damage reduced. The sounds made while firing are the same for most suppressed guns. However, the Commando, Galil, AK47, FN FAL, M14 and M16 do have a unique firing sound when a Suppressor is equipped.
Following the title update for Call of Duty: Black Ops, damage multipliers were increased for headshots on all sniper rifles that have an attached suppressor, making one shot kill headshots possible in all Core playlists. Prior to the 1.06 patch, however, players using Warlord as their Tier 2 perk and attached both a Suppressor and another attachment, the headshot multipliers did not take effect.
In the Nintendo Wii version of Call of Duty: Black Ops, the Enfield, Galil, AK47, and Commando have their fire rate reduced from 750 RPM to 625 RPM when equipped with a suppressor.
Suppressors are first seen on two weapons, the M14 and the Hush Puppy, though it is also available for the Dragunov, the PPSh-41, the Makarov PM, the M40 and the M10, and integrated into the Mk. 22 Mod. 0. It will prevent enemies from reacting to the player's shots, and keeps the player off the radar in multiplayer when shooting.
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".
In multiplayer, it can be used on nearly all the weapons with the exceptions of Launchers, the Model 1887, revolvers, and the Desert Eagle. 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 versions, making the player not appear in the mini-map when firing, reducing the muzzle flash, sound and reducing the minimum and maximum range of the weapon by 25%. Suppressed sniper rifles have their base damage reduced at all ranges as in previous games. Silenced Light Machine Guns are still able to kill in three hits or less under normal circumstances, causing little detriment other than the opportunity cost of not using another attachment.
Like in previous games, when the player fires a weapon with a Suppressor, they do not appear on the mini-map as a red dot, giving a stealth advantage. In addition, the shots are quieter and the weapon's muzzle flash is removed; however, using the Suppressor results in a loss of range. This is not the case for sniper rifles; instead their damage multipliers are modified, meaning fewer one-shot-kill areas. It also reduces center speed by 2%, resulting in a very slight recoil increase. To prevent compensation for the range loss, Long Barrel is not available when using a Suppressor.
The Suppressor appears in Zombies with a limited role: it can be obtained on the DSR 50 as one of the attachments gained when repeatedly Pack-a-Punching the weapon. It is also acquired on the Mauser C96 when Pack-a-Punched. Unlike in multiplayer, the attachment gives no stealth bonus at all, other than the reduced muzzle flash (which is arguably not a notable trait due to muzzle flash not showing when scoped in) and instead occupies one of the possible attachment slots, making it a rather bad final attachment choice.
"Invisible on radar when firing and reduces muzzle flash. Shortens effective damage range."
— In-game description
The silencer returns in Call of Duty: Ghosts. It prevents the player showing up as a red dot on the radar when firing, and reducing noise and muzzle flash of the gun in exchange for reducing range by 25% (or multipliers on Sniper Rifles). An interesting thing in the game code is that every weapon class has a separate code where it says the percentage of range lost. This means that in the future Infinity Ward will be able to change the effect of the silencer separately for each weapon class. The silencer has a different effect on sniper rifles; the multipliers of the weapon are changed so that the player gets fewer one shot kills to certain parts on the body. The Honey Badger, K7, and VKS have an integral suppressor, meaning that those weapons have the effects of the silencer as default instead of an extra attachment option.
In the campaign mission "Aftermath", the suppressor on the Bal-27 is equipped with an integrated flashlight.
In Exo Survival, on the map Riot, the suppressor can be seen in the ending cutscene, as well as the Outbreak map opening in Exo Zombies. After an update, it is now also used by enemy Cloaked soldiers after the map is flipped.