he AT4 is seen on ally Marines, but is unusable by the player (unless you use cheats). It's only used by allies twice; both times in "Shock and Awe". The first one is after some allies are let out near the statue. One of them has an AT4 and will fire it after hiding behind a wall. He's very close to the player, so they should see him get into position and fire before the player takes off. The last time is when the player gets to the stranded allies in the under-construction building; one of them will fire it into the crowd of troops right before the player gets to the top. It is occasionally seen carried by Ultranationalists, but they never use it.

The AT4 can be used on the levels "Shock and Awe" and "Game Over" by cheating (this will only work on the PC version). The gun, which is normally dropped by NPC's after firing, has no reloading animation. So when it is fired by using the cheat, it is just suddenly reloaded and ready to fire again.

The AT4 debuts as a usable weapon in Call of Duty: Modern Warfare 2. This version is called the AT4-HS (Heat-Seeking) as it is capable of locking on to aircraft. To lock-on, the weapon must be ADS aimed at the aircraft until a clear, loud tone is heard then fired. Even when locked on, the AT4 occasionally misses. These misses may be caused by the user firing before the tone is perfectly clear and loud.

In-game it can also be dumb-fired without locking on, operating like a more accurate but weaker RPG-7. This makes it somewhat effective against infantry and ground equipment, if a bit underpowered. However, only a single rocket is available, (you can re-load the AT-4 if you are using the Scavenger perk) so once used it is highly recommended to replace it with another backup weapon.

In terms of strategy, the AT4 does not replace the Call of Duty 4: Modern Warfare's RPG in terms of multiplayer combat. The AT4 takes crucial moments to switch to, load, and ready. Also, the ability to melee is slowed down due to the bulky nature of the device. Players using the Scavenger perk can pick up extra rockets from recently killed players from both teams, the transitioning between swapping out the launcher is slow but ensures that the AT4 has a second rocket available during the match.

The AT4 is weaker than the Stinger or Javelin for taking out aircraft and inferior to the Thumper for clearing out buildings. However, it can fill either role since it doesn't require a lock-on but there is one available. This inferiority is further mitigated by the fact that the weapon is available in the earliest stages of the game and that, unlike the Thumper, the AT4 has no arc to worry about. Finally, it can be dumb fired against aircraft, exposing the user for a shorter period of time than waiting for lock and avoiding the aircraft's flares. This is only recommended against slow moving aircraft.

Like the RPG the AT4 must be fired from iron sights. Pressing the fire button from the hip will raise the iron sights first before firing. The AT4 sights are extremely obtrusive with a very large frame blocking the area surrounding the target. When fired, the AT4 has a slight delay before the rocket exits the tube. The firing sound will play but if the user is killed before the rocket fully leaves the tube the shot will not fire.

Like the Javelin the AT4 has slightly unusual loading behavior when used with Scavenger. An AT4 user may carry two missiles, one in reserve and one in the launcher itself. However, additional missiles can only be picked up if the launcher is actively equipped and the reserve slot is open.

One major advantage the AT4 has over the RPG is that the AT4's missile flight is almost perfectly straight, while the RPG can go wildly off course. Even at long ranges, the AT4 is highly accurate, similar to a decently accurate assault rifle, while with the RPG you have to be very lucky to hit your target.

The AT4-HS also has an issue where even if the user does not lock onto a high kill streak reward (such as the Pave Low or Chopper Gunner) the missle is still thrown off course from the flares.

Trivia