Laser Sight

"Laser sights here!"

- The Survivors

The Laser Sight appears in Left 4 Dead 2 as a tool used to enhance the accuracy of weapons and show other survivors where your line of fire is. Laser Sights can only be attached to any primary weapon when using a Laser Sight pile.

Once attached, a Laser Sight sticks to the chosen weapon and cannot be transferred to any other weapon. This also applies to weapons of the same type - swapping a Laser Sight-equipped Combat Rifle with another Combat Rifle will not grant the new one a Laser Sight, nor will it remove the sight from the old gun.

Tactics

 * A Laser Sight can aid your aim and decrease spread considerably, so your best bet is to attach one to an AK-47 or Silenced Submachine Gun. Powerful but highly inaccurate weapons that fire fast can become devastating when paired with Laser Sights.
 * Shotguns are meant to have a wide spread to be effective at close-range, which goes against the purpose of Laser Sights.
 * The spread-decrease buff does not do anything for the Grenade Launcher, which technically fires the grenade as accurate as possible.
 * If players have a hard time firing their sniper weapons accurately, Laser Sights may enhance their aim.
 * For the Hunting Rifle, Sniper Rifle, and Grenade Launcher, only their moving accuracy is improved.
 * Other players can see your Laser Sight even if you're behind them, making it easier for them to avoid stepping into your line of fire which is essential in difficulties with high friendly fire damage.
 * Laser Sights are incredibly rare. Try finding and using a more suitable gun close to the Laser Sight pile if possible, then hold on to the upgraded gun as long as you can and avoid swapping it. If not all of the team have Laser Sights and a Survivor with one dies, it can be a good idea to salvage the weapon to take full advantage of the sight.
 * You cannot attach Laser Sights to sidearms. This also means you don't have to worry about swapping a Laser Sight-equipped secondary weapon.
 * Laser Sights make it much easier for Survivors to find each other without silhouettes in Realism Mode.
 * Unlike Explosive and Incendiary ammo boxes but similar to Foot Lockers and Ammo Piles, an unlimited number of Laser Sight upgrades can be obtained from every Laser Sight pile. If you find a better weapon shortly after attaching one, you can backtrack to upgrade your new weapon.
 * While rare to find both in a single level, the M60 benefits greatly from the addition of a Laser Sight, helping an already deadly weapon land more shots on targets.
 * The Survivor Bots are capable of finding and equipping Laser Sights themselves but are not likely to actually announce it, usually returning to the player(s) without a word. If you suddenly notice the sights on the Survivor Bots, it might be a wise choice to explore the area for the sights.

Behind the Scenes
The Laser Sights were originally an upgrade in the original Left 4 Dead. Along with the upgrade system, it was cut and rendered unused for the final version. Mods on the PC version can restore these upgrades, which lets players use the aforementioned Laser Sight.

Accessibility
The Laser Sight pile is a very rare find; players can often play most campaigns without spotting a Laser Sight at all. They can be found in all campaigns. Since the Laser Sight cannot be transferred from weapon to weapon, the ideal solution when finding one is to equip it to a weapon the player intends to keep. The only areas that have fixed Laser Sight pile spawns are Whitaker's Gun Shop in "Dead Center" and under Memorial Bridge in the 3rd chapter of "Cold Stream".

Usually, Laser Sights generally only appear once per campaign if the AI Director decides to spawn them. Rarely does the Director spawn two in the same campaign. Sometimes the two Laser Sight piles spawn in separate chapters of the campaign, and other times they can appear together in the same chapter, such as Whitaker's Gun Shop and in a tent after the Crescendo Event.

In the first level of "Dark Carnival", a Laser Sight pile may spawn on the motel roof near the billboard where a Hunting Rifle is found. Survivor Bots usually need help to direct them to it as being closer to a player is a higher priority. Another example where Laser Sights are often found is in the second level of Dark Carnival, located on one of the game stalls or in the bathrooms near the area where Gnome Chompski is found. "Swamp Fever" has a high chance of spawning Laser Sights if playing from start to finish.

Just like any other entity in the game, you can spawn the Laser Sight pile using  in the console, placing it on your crosshair's spot. This requires  to be active.