Grenade Launcher

"Man, it's gonna be raining zombie pieces!"

- Coach

"Time to make some zombie soup!"

- Nick

The M79 Grenade Launcher is a primary weapon that made its debut in Left 4 Dead 2. When fired, it launches an explosive shell that kills Common Infected and weaker Special Infected. Any Infected that aren't killed by the blast are damaged and stumbled, except for the Tank, which doesn't stumble. It can only hold one shell, however, and has a long reload between shots.

The Grenade Launcher is unique in that it isn't found along with Tier 1 or Tier 2 weaponry, but instead is found somewhat rarely in side passageways and rooms, typically where the Chainsaw can also be found. The Grenade Launcher can't refill its ammunition reserve with a normal Ammo pile, meaning that the only way to get more grenades is to find another Grenade Launcher or use an Ammunition Upgrade.

Achievements
This achievement can be hard to do in normal circumstances, but it can be easily done during a horde attack:
 * Firing at Infected climbing fences or walls.
 * Firing at Infected attracted by a Bile bomb or Pipe bomb.

Tactics

 * Friendly Fire damage on the Grenade Launcher isn't too high on lower difficulties, but it definitely stacks up and gets higher with difficulty. Watch for your teammates whenever possible to avoid hurting them.
 * Due to the fact that the Grenade Launcher can't refill ammunition, it's best that you wait until you find a bunched up group of around four or more Infected, and use your secondary on smaller groups.
 * The Grenade Launcher pushes back Special Infected that are pinning your teammates if it doesn't kill them. Take advantage of this when your teammate is pinned and you can't shoot or melee the Special Infected off.
 * The Laser Sight doesn't really provide the Grenade Launcher with any benefit due to its ballistics arc. Unlike all the other weapons, it has absolute constant firing behavior and accuracy at any range and no damage dropoff.
 * The Grenade Launcher works best with the Magnum or Dual Pistols, as a melee weapon forces you to give up the range you need to use the Grenade Launcher best. However, planning ahead on encountering the grenade launcher isn't worthwhile due to its rarity, and it's always recommended to get a melee weapon as a sidearm for encountering Hordes.
 * Incendiary ammo with the Grenade Launcher is redundant unless fighting a Tank or Witch, although Explosive Ammo will give you a slightly more potent blast. Keep in mind, however, that both piles will give you an extra Grenade.
 * A tactic you can use with the Grenade Launcher is to continually switch between your primary weapon and the Grenade Launcher as you travel so that you always have one or the other. This is impractical over long distances where it's better to just go with one or the other, but in areas like Finales, it can be helpful.
 * The Grenade Launcher can be used to detonate static explosives such as the propane tank and Gas can. This can make it useful when setting up for a finale, although it makes the Grenade Launcher a hazard in Scavenge Mode and the finale to Dead Center.
 * The Bile bomb works well with the Grenade Launcher, as it makes it easy to bunch up large groups of Infected and get them at a safe distance to avoid friendly fire damage. However, the Bile Bomb also spawns Common Infected in addition to drawing nearby Common Infected, and when it wears off, any lingering common infected will attack the nearest Survivor.
 * If you can put a Propane tank in the way of a Tank, you can use the Grenade Launcher to detonate it, stumbling the Tank and damaging it with both explosives. This tactic can also be used with a Gas can to set the Tank on fire.
 * Particularly used as an equalizer in versus, even after Points of No Return (found in several places in several maps, such as Tunnel of Love's small hole on the floor, or The Parish' Balcony near the festival stand) it can find its way and kill or at the very least stumble special infected from a teammate who either got caught by a lucky smoker, or didn't otherwise keep up with their team. However, it can also be used at very very long ranges, with a little skill and luck, you can save a teammate very far away grappled by a Special Infected, particularly in swamp fever, even without clear line of sight.

Trivia

 * It is modeled after the M79 grenade launcher.
 * While the Grenade Launcher can kill most Special Infected in one hit, it will only push off a Jockey.
 * The grenade launcher can be used to blast open walls that otherwise only a Tank can break open.
 * When being killed or hit by the grenade launcher, the Special Infected players' ears will ring.
 * The ammo's model states that it is a PWN 40MM HE NADE.
 * There are only a few places in the game the Grenade Launcher can always be found. One of them is on one of the towers in The Concert.
 * The Grenade Launcher seems to have been left behind by military or police forces when the Survivors pick it up, although this doesn't explain why it shows up so often in Swamp Fever, which has a specified lack of any military or CEDA influence. However, there is the possibility that they were possessed illegally.
 * The grenade launcher is not found in Whitaker's store because civilian possession of ballistic firearms is illegal in the United States. However, Whitaker's grenade launcher was either illegally owned or a possession of his from serving in the military at one point in his life.
 * The witch is stumbled (even when startled) by the launcher blasts.

Videos

 * Swamp Fever Grenade Launcher Gameplay
 * PAX Dark Carnival Grenade Launcher Gameplay