C4

Composition 4, also known as C4, is an explosive featured in Call of Duty 4: Modern Warfare, Call of Duty 4: Modern Warfare (Nintendo DS), Call of Duty 4: Modern Warfare (Mobile), Call of Duty: Modern Warfare 2, Call of Duty: Black Ops ,Call of Duty: Modern Warfare 3, Call of Duty: Black Ops II, Call of Duty: Black Ops Declassified and Call of Duty: Ghosts. It is thrown into place and detonated with an M57 Firing Device, also known as a "clacker".

Campaign
The C4 is constantly seen in the campaign as the primary tool to destroy key objectives, where the player would have to arm the explosive and travel to a safe distance before detonating it. An example of this would be in the level "The Bog", where the objective is to destroy the ZPU-4 in order for a friendly helicopter to pass by. The player also destroys an electric tower with C4 in the level "Ultimatum".

Multiplayer
The C4 is a first tier perk and the player will get two when it is used, it has a higher damage and splash damage than the Claymore. When the perk is used, press left on the D-Pad and a detonation trigger will be pulled out, then by pressing the special grenade button (L2 on PS3, Left Bumper on Xbox 360) (ADS button in PC version) the C4 will be thrown, which will stick to walls, cars, etc. Pressing the equipment button (R2 on PS3, Right Trigger on Xbox 360) (attack button in PC version) will then detonate the C4, albeit with a .83 second delay. Alternatively, C4 can be detonated by double tapping the reload button (use button in PC version) while the player's main weapon is out.

The C4 is a questionable choice in multiplayer modes due to the necessary remote detonation of the C4, which may prove troublesome for snipers and is commonly used by those who wait for someone to walk into the C4 then detonate it. The Claymore is a preferable weapon for Sniper players who rely on actually sniping, negating the need to an eye on the C4. They often have no time to detonate the C4, whereas the Claymore detonates automatically when an enemy walks in front of it.

Call of Duty 4: Modern Warfare (Nintendo DS)
C4 appears in Call of Duty 4: Modern Warfare (Nintendo DS).

Call of Duty 4: Modern Warfare (Mobile)
The C4 used in Call of Duty 4: Modern Warfare (Mobile) is used to take down radio towers in the level, "Civilian Town". Instead of it being thrown and remotely detonated, it is placed and ticks down for some time before exploding.

Campaign
C4 appears in Call of Duty: Modern Warfare 2 as an explosive used by Task Force 141 and by the U.S. Army Rangers. It appears in three campaign missions, "Of Their Own Accord", "Cliffhanger" and "The Only Easy Day... Was Yesterday".

In Spec Ops, C4 appears in the missions, "Acceptable Losses", "Wreckage", "Hidden", "Suspension", and "High Explosive".

Multiplayer
C4 returns in Call of Duty: Modern Warfare 2, this time in the equipment slot instead of via perk. Another change is players are given only one C4. However, the throwing range of C4 is very low, requiring deliberate placement rather than throwing. Also, because it is in the equipment slot, it can be placed with a single button. This is noticeably faster than Call of Duty 4: Modern Warfare's method, which required switching to C4 as a weapon via the directional pad and then throwing it. But detonating is slower, since there's an animation of pulling out the detonator and activating it, in contrast with having the detonator already equipped in Call of Duty 4: Modern Warfare. Campaign retains the method of assigning C4 to a directional pad button. However, C4 will detonate instantly if reload (use on PC) is pressed twice, essentially negating such disadvantages.

As with the previous game it is useful to place it on objectives (I.E. Domination flags, Sabotage targets, etc.) and use it as a mine whenever an enemy nears it. This tactic is particularly useful in Domination, as the announcer will comment on when an enemy nears an objective, making it possible to get defensive kills without having to watch the flag.

It can be used as a rudimentary grenade, but cannot be thrown as far and must be detonated by the player. However, unlike fragmentation and Semtex grenades, there is no warning indicator for a nearby C4 satchel. It also has a larger lethal radius than its grenade counterparts.

C4 will detonate if the player presses reload twice very quickly, (Except on the PC, where the player must tap the "Use" key twice), which can be useful if the player has C4 previously set that needs to be detonated, but already has C4 in inventory from Scavenger or One Man Army. In this case, pressing the equipment button will not detonate the C4, it will simply cause the player to throw another C4.

There is a glitch that causes a detonated C4 pack to do no damage to an opponent whatsoever (no hit marker appears) no matter how close the enemy is to the C4 pack, or whether Danger Close is equipped or not. This glitch is currently active, though it may just be due to lag. This may be connected to another glitch that causes the C4 to show the explode animation but cause no damage. If any players walk into the explosion spot after a time of around 5 seconds, they will die (tested on PC in a private match via shared LAN connection).

A tactic used with C4 is to plant C4 in front of a Claymore, so when an enemy activates the Claymore it will set off the C4. The best perks to use for this tactics are One Man Army and Danger Close.

Call of Duty: Black Ops
"Two plastic explosives devices that are detonated remotely with the clacker or by double-tapping "use" button"

- Create-a-Class 2.0 description

Campaign
C4 is first seen in the level "Executive Order," where Mason uses it to blow up a wall to access the controls to the Soyuz 2. It is later seen in "The Defector," where Mason uses it to blow up the ceiling beneath a ZPU-4. It's final use in the level "Victor Charlie", where the player is tasked with covertly planting C4 in a Vietnamese village and running to a safe spot. The player then detonates the C4 to ambush Viet Cong. The only time when the player can use it at will is in "The Defector", when at the end of the mission where the player has to defend the docks. C4 can be found on a crate (like the claymores) and used normally to help defending.

Multiplayer
C4 is available in multiplayer for. It can be bought after Create-a-Class is unlocked at level 4. The C4 in Black Ops is almost exactly the same as the Call of Duty 4: Modern Warfare and Call of Duty: Modern Warfare 2 versions (featuring nearly the same skin, but lacking the flashing red light), but the player is armed with two C4s that can be placed and picked up after being deployed, unlike in Call of Duty: Modern Warfare 2. They are deployed via the "aim" button, and can be detonated by either quickly double-tapping the reload button (use key on PC) or using the detonator. The C4 can be thrown much further than in previous games.

Campaign
C4 was used by John Price and Yuri during their infiltration of Makarov's castle, as well as to cover their escape. Yuri had planted one packet on a bridge column, another on a bottom of a platform, and Price planted one packet on the bottom of an enemy transport truck. It is later used to breach the room where the Russian President was being held captive in the form of C4 belts.

Multiplayer
C4 is unlocked at General III (Level 69) in Call of Duty: Modern Warfare 3 ' s multiplayer. It is similar to the Call of Duty: Modern Warfare 2 version, as it can be thrown with only a single button, but has a much higher throwing range. Also, detonation without double-tapping reload or use is faster; tapping the equipment button once deploys the explosive, while pressing the button anytime later will immediately pull out the detonator, click it, and quickly put it away; this takes about as much time to complete as calling in a Spy Plane or Counter-Spy Plane in Call of Duty: Black Ops.

Survival Mode
C4 was first seen in Call of Duty: Modern Warfare 3 ' s Special Ops Survival Mode trailer. It can be purchased in this mode in increments of five for $1500.The player can have up to ten at once and can buy more after placing them. However, only twenty can be placed at once; if another is placed, all previous ones are automatically detonated. C4 is a very effective weapon to use against Juggernauts. Up to wave 25, placing five or more blocks of C4 at the site where the Juggernauts are deployed or a spot you lead them to after landing will instantly kill them.

Call of Duty: Black Ops II
"A plastic explosive device that is detonated remotely with the clacker or by double tapping 'the use button.'"

- Create-A-Class Description.

C4 returns in Call of Duty: Black Ops II. It is fairly popular, especially when combined with Scavenger and / or Fast Hands. This combination is surprisingly potent, allowing for kills over walls and around corners with ease, as well as a backup weapon if a player would normally need to reload while under fire. C4 also carries the benefit of destoying enemy equipment without exposing the player, which is especially useful against  Sentry Guns, Guardians and enemies using Assault Shields. Furthermore, it maintains the tactical use as a triggered explosive, when a player is expecting an enemy to appear around a corner.

It is worth noting that hacking the C4 with a Black Hat PDA will steal control of the explosive on the ground, but if hacked in mid air, the explosive will remain in possession of the hacker until it hits the ground, at which point it returns to the thrower.

Call of Duty: Ghosts
C4 returns in Call of Duty: Ghosts. It performs identically to its counterparts in previous games. The detonator and C4 charge from Modern Warfare 3 is reused for breaching on the multiplayer maps Warhawk, Octane, Fog and Containment. To breach a wall, hold the use button near the wall. The player will place a C4 charge on the wall and then it will detonate a few moments later. An exclamation point will appear on the map when someone does this.

General

 * C4 can tend to bounce off of moving enemies when it hits them on the head or in certain areas of the character model at certain angles, such as the foot when it moves forward, making it seem like the enemy "kicked" the C4. By the time the user clicks the firing device as quickly as he threw it, it would have bounced back to them and will explode in front of them, causing an accidental suicide.

Call of Duty 4: Modern Warfare

 * In Call of Duty 4: Modern Warfare, when the player sprints, a package of C4 explosive can be seen in his left hand, even after he has no more C4 packs left.
 * The C4 makes an appearance in the extended level of "F.N.G.", where Newcastle teaches the player how to arm and detonate C4. He says "Looks like my ex-wife was kind enough to donate her car to further your education Soap." Watch this video.
 * If one places C4 on the window of a car then knifes the window, the C4 will drop between the car seat and the door, rendering the C4 invisible to enemies without the right perks. This makes an effective bomb, especially deadly to anyone taking cover behind the vehicle.

Call of Duty: Modern Warfare 2

 * If C4 is stuck to a pane of glass and the glass is subsequently broken, the C4 will appear to be floating in midair as if still stuck on the glass.
 * In third person mode, when the equipment button is pressed the player's character will hold the C4 and throw it, even if there is no C4 left.
 * C4 is affected by Flash and Stun grenades, being unable to detonate until the effect wears off, similar to the Claymore.
 * If C4 is thrown on a Riot Shield, it will bounce off instead of sticking to it.

Call of Duty: Black Ops

 * In Call of Duty: Black Ops, C4 cannot be destroyed by the Ballistic Knife, or any Grenade Launcher.
 * Placing C4 on an enemy RC-XD will cause it to explode. However, if placed on a friendly RC-XD, it will not do any harm.
 * In the Wii version of Call of Duty: Black Ops, detonating C4 on the right place when it is placed on the rocket in Launch causes hitmarkers to appear.
 * If a player throws C4 just as they die it will create a "fake" enemy C4 charge being unable to detonate and will stay wherever it was placed until the game ends. This C4 will have a red light and is not even affected by gunfire or killstreaks.
 * A fake charge of C4 can be found on the RC-XD that is included in the Call of Duty: Black Ops Prestige Edition.

Call of Duty: Modern Warfare 3

 * When having a C4 firing device or a Claymore in Survival Mode, the damage of a knife attack is roughly doubled.
 * The C4 used in the Dead Man's Hand deathstreak produces a much larger explosion than a normal C4, comparable to that of a javelin rocket explosion.
 * If C4 is caught in the blast range of a flashbang while in mid-air, the air where it was will spark for some time.
 * When using an assault rifle, LMG, SMG, Shotgun or Sniper Rifle, along with a Machine Pistol, putting away the firing device is normally slow, where the player will turn off the firing device, then put it away, but if using a pistol, the player automatically switches to the pistol, and then the clicking of the firing device being disabled is heard.
 * It is possible to detonate C4 while controlling a Pointstreak (e.g. Predator Missile), by double tapping the "Use" key.
 * The C4 used in custom default classes has a slightly different sound than it's create-a-class variant.

Call of Duty: Black Ops II

 * When bots use C4, they will detonate it when an enemy is near the C4, regardless of whether or not they can see the enemy, essentially making the C4 a proximity mine.
 * A popular tactic that players use with the C4 is to place a Shock Charge on the C4, or near it. When an enemy triggers the Shock Charge, the player who planted the Shock Charge can detonate the C4, effectively killing the enemy.
 * It is possible to see writing on the C4, such as "IF EATEN".

Call of Duty: Ghosts

 * In the multiplayer reveal trailer the inventory icon for C4 was shown to be the same as that from Modern Warfare 3. This was likely a placeholder.