Flashbang

The M84 stun grenade is the flashbang used in Call of Duty 4: Modern Warfare and Call of Duty: Modern Warfare 2. A flashbang is a grenade that releases a flash of light that momentarily activates all photosensitive cells in the retina, making vision impossible for approximately five seconds until the eye restores the retina to its original, unstimulated state.

Subjects affected by flashbangs describe seeing a single frame for the five seconds (as if their vision was "paused") until it fades and normal sight returns. This is because the sensory cells which have been activated continue sending the same information to the brain until they are restored to their resting state, and the brain translates this continuous information into the same image. The incredibly loud blast emitted by the grenade contributes to its incapacitative properties by disturbing the fluid in the semicircular canals of the ear.

The flashbang has been around for almost five decades, because the British Special Air Service needed a non-lethal incapacitant for special operations. Although there are many different types, the one used in Call of Duty 4: Modern Warfare is modeled on the US M84 stun grenade, manufactured by Picatinny Arsenal.

The flashbang is an essential item for both Modern Warfare and Modern Warfare 2, especially when playing Veteran difficulty. AI-controlled enemies are responsive to flashbang detonations and it is required to consistently defeat certain foes, such as the Juggernauts

Tactics
The Flashbang grenade can be effectively used on a defended location or around a corner. Flashbangs will detonate seconds after being thrown. They cannot be cooked. If the target is close enough and looking at the detonation site, they will be temporarily blinded and deafened. The target’s reaction is still in real time so they can run or backpedal to evade, however, they cannot sprint while affected. They can still easily fire, making any enemy in front of them a potential kill. Affected targets will raise an arm to cover their eyes, signaling to the player that they are blinded.

In the single-player game, the player spawns with flashbangs, and can find additional grenades in grenade bags, but they only appear in the bags if the player has already expended some their own flashbangs. In multiplayer, if the player goes into Last Stand while prepping a flashbang it will turn into a frag grenade. Flash Grenades detonate exactly one second after being thrown; they do not have to impact the ground like Stun grenades.

Because it only affects players' vision if they are facing towards it, a viable tactic is to turn away before it detonates or to duck behind cover; this is most effective if a player must throw a flashbang in close proximity to its intended target. Additionally, the flashbang inflicts a small amount of damage (15 points) if they physically strike a player, which can kill a target with low health.

It is useful in Modern Warfare 2 to add the Scavenger Perk to it (especially when playing maps such as Favela where there are numerous rooms and buildings player can be in for tactical advantages (or for hiding)). By doing this, the player can consistently do a flash-and-clear method of approaching buildings (this is, however, ineffective unless the player is killing enemies to help resupply themselves). For this reason, it is best to do this when there is a higher probability that someone would actually be in the building (ex. don't flash buildings really close to where your team is spawning as the probability of someone being in that building isn't as high as someone being in a building further into the center of the map). This also disables claymores set up by individuals to watch themselves while inside the building (ex. snipers). This tactic is best used on the maps Favela and Invasion where house-to-house fighting abounds more than the typical map.

If on a hardcore game type, you can actually kill an enemy player by throwing a special grenade at their head. It isn't really useful, but will make a good final kill in a Hardcore Search and Destroy, if there is 1 last enemy player left, and they are planting/defusing the bomb. Note: this will only work in MW2 at the moment.

Versus Stun Grenades

 * In Call of Duty 4: Modern Warfare a flashbang does not indicate if it has affected the enemy, making it difficult to discern whether it has had any effect. Stun grenades, by contrast, show the damage indicator if they've affected anyone, thus making stun grenades more popular. However, in Call of Duty: Modern Warfare 2, flash grenades also produce hitmarkers on successful hits.


 * Flashbangs have a larger effective radius than stun grenades; this is a double-edged sword, as flashbangs are more likely to affect the thrower as well. At the edge of the radius, players are only affected if they are looking in the direction of the flashbang.


 * Flashbangs do less damage to affected targets than stun grenades do; a stun grenade is more likely to kill a wounded player.


 * Flashbanged players are simply blinded and deafened but move just as fast (though they cannot sprint.) Stunned players move and aim more slowly.


 * Flashbangs will explode in midair. Stun grenades must impact something first.


 * Flashbangs take about twice as long as stun grenades to arm and throw. This makes it more likely that an enemy will encounter you while you are deploying one.


 * A flashbang can completely disorient a player, as it blinds them and removes any extravisual perception. Players affected by a stun grenade, however, can still see clearly and react to their surroundings, albeit very slowly.


 * Blast Shield protects users from stun grenades but Flash Grenades will still blind a Blast Shield user.


 * Because Stun Grenades slow the enemy, require hitting a surface and have a smaller blast radius and indicate if a target has been affected, they are used more often than flashbangs.


 * Flashbangs can disable placed C4 and Claymores temporarily.


 * In Call of Duty: Modern Warfare: Mobilized, you can tell if someone has been flashbanged by their movement. If they have, they will be moving back and forth, firing single shots randomly, and covering their eyes.

Trivia

 * The Spetsnaz forces shout something as "flash bang", this being incorrect. Flashbang in Russian is светозвуковая граната (svetozvukovaya granata).


 * If a player throws a flashbang and it detonates in mid-air, it affects a larger radius.


 * The flashbang affects players somewhat even when they are not looking directly at it.
 * Flashbangs can be thrown while climbing a ladder.
 * The flashbang in-game sports an olive drab finish. The real-life flashbang sports a black finish.