C4

C-4 or Composition 4 is a common variety of the plastic explosive known as Composition-C. It is 1.34 times as explosive as trinitrotoluene (TNT), or Dynamite.

Characteristics and Uses
C-4 detonation velocity is 8,040 m/s (26,400 ft/s), or 28,900 km/h (18,000 mph).

C-4 is often used in demolition charges such as the M183 and M112. The Demolition charge M183 is used primarily in breaching obstacles or demolition of large structures where large charges are required (satchel charge). The M183 charge assembly consists of 16 M112 block demolition charges, four priming assemblies, and M85 carrying case. Each Priming assembly consists of a five-foot length of detonating cord assembled with two detonating cord clips and capped at each end with a booster. The components of the assembly are issued in the carrying case. The demolition charge M112 is a rectangular block of Composition C-4 approximately 2 inches (51 mm) by 1.5 inches (38 mm) and 11 inches (280 mm) long, weighing 1.25 lb (0.57 kg). When the charge is detonated, the explosive is converted into compressed gas. The gas exerts pressure in the form of a shock wave, which demolishes the target by cutting, breaching, or cratering

Battlefield 2
C4 used by the Special Forces class. Most commonly used to destroy enemy armored vehicles, as well as enemy installations such as Artillery and UAV Trailers.

Singleplayer
In singleplayer, the C4 is called DTN-4. When picked up, the player has 5 satchels of C4 and the detonator. The C4 is deployed with the R1 button (PS3), but subsequent satchels must be first equipped, otherwise the layer will detonate the C4 accidentally. It is useful against all vehicles (except MBTs), bridges and buildings.

Multiplayer
Used by the Specialist class, the C4 must be unlocked. C4 can be thrown short distances and is detonated remotely by the player. The C4 is usefull for breaching walls. It can destroy most vehicles with a single pack. The player can place multiple packs to assure destruction.

Singleplayer
The C4 in single player is very similar to the DTN-4 in Bad Company, except that the player doesn't need to equip the C4 in advance of deploying it. It can be found on lots of levels, but doesn't carry over to the next level in the campaign. When equipped, the player can deploy a maximum of 6 satchels at a time, and after that, the satchels disappear. It can be useful against vehicles, bridges and buildings, and can also be a very good smokescreen for the player.

Multiplayer
In Bad Company 2's multiplayer, C4 is used by the Recon class, or by the Assault class when using a weapon unlocked for all classes, and it is the most powerful explosive available in-game (except for the ATM-00, which has the same damage.). Generally, C4 has the same characteristics as in Bad Company, except that the player doesn't have to switch from the detonator to the satchels. A common tactic, often used in Rush is to fill the house or room that the station is with C4, then when the bomb is planted the user destroys the building and kills everyone in it, this often results in double, triple, or multi-kills. In a rush game, it takes 12 C4 charges to destroy the objective.

Another strategy is to use it in combination with the Motion Sensor. Throw some C4 (two or three) on a vehicle that your team doesn't want to use, and then throw a motion sensor close to the vehicle. If a player gets near it, or even in it, you can use the audible notification as a signal to detonate the C4, destroying the vehicle and those using it.

A tactic is to go "kamikaze" with your squad by loading a vehicle with C4 that's out of their firing range, have one player hop on, and detonate upon his voice command(or, plant a motion sensor in the vehicle for surefire success). Of course, this shouldn't kill him, unless the enemies get wise to your tactic and shoot the C4 or prematurely destroy the vehicle.(unconfirmed)

A good tactic for Recon players is on Arica Harbour as the Defenders. By going ahead of the main base toward the attackers deployment point, players can use the vehicle wreckage as cover and plant C4 on the roads. With careful timing, a good Recon can detonate C4 charges to destroy or damage incoming tanks and vehicles. Couple with an Assault Class and equipped with weapons like the SVU or VSS can make you a useful player to your team as you can restock C4 without having to equip the Explosives upgrade and spot and kill running infantry.

In Rush, a good tactic for taking out objectives in small buildings, such as Alpha in the first base on Port Valdez, is planting C4 on the key supports of the buildings, or one on each wall. This won't only destroy the objectives if successful, it will also earn you the "Demolish" achievement for destroying 1 house worth 10 Gamerscore, (gamerscore unconfirmed, please correct)

In Rush, a sly tactic for the attacking team to demolish M-COM Stations is to sneak onto the point, and cover it in C4 charges. With the demolitions upgrade active, 12 C4 charges will destroy the point. With this, 2 players can 'one-shot' an M-COM Station by using the demolitions upgrade (additional explosive damage), along with the explosive ammo upgrade (twice the amount of C4 carried, taking it from 3 to 6). If the players are not seen by the defenders while they are setting the C4, and do not arm the timed charge (setting off a warning), there is absolutely no way the defenders are made aware of the operation, and once either of the C4ing players detonates their charges, the point is lost instantly.

Another variation of this tactic is to have 3 players - 2 of which are using the double explosives carried, and demolitions damage upgrades. The third player pilots a UAV vehicle, while the other two cover it in a total of their 12 C4 charges. The UAV is then flown to the M-COM station, landed on it, and the charges are then detonated. This is only possible if the M-COM station is out in the open - if it is safely inside a house, the UAV will not be able to get close enough unless a wall has been blown open.