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.
 * Firing at Infected trying to attack you while you're on the rescue vehicle.

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.
 * Usually, if shooting directly at a group of rushing Common Infected, you'll hit a few in the front, and only stumble the ones behind them. To get the most out of a single grenade, shoot from above and aim for the middle of the horde to kill the most Infected.
 * In crescendo events where the horde must climb a ladder to get to the Survivors, the Infected are helpless and predictable while climbing. Use this to your advantage and kill large amounts of Common Infected at once.
 * 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, be ready to clean up remaining Infected that don't bunch up.
 * The Grenade Launcher stumbles Special Infected that are pinning your teammates if it doesn't kill them. This can be used to save a team mate pinned at a point of no return or from far away.
 * If a Smoker starts to pull you, the Grenade Launcher always has the same accuracy even when moving, so you can easily land a grenade on him and save yourself.
 * While the Grenade Launcher doesn't do very much damage to a Witch, it does stumble it, meaning that if someone else disturbs it, you can stun the Witch to help them run away and make it easier for everyone to kill it.
 * With a direct hit, the Grenade Launcher does 1000 damage to a Tank. You can also use a Propane tank to make the Tank stumble while you reload, or a Gas can to light it on fire.
 * The Dual Pistols and Magnum work best with the Grenade Launcher, although melee weapons are still highly useful for fighting in close quarters with low risk of friendly fire.
 * The Chainsaw isn't recommended, however, as both weapons are damaging to team mates in tight spaces, both have limited capacities and are hard to come by, and between the Grenade Launcher's reload and the Chainsaw's draw time, you're generally better off with a more reliable weapon.
 * The Laser Sight doesn't really benefit the Grenade Launcher, as it always fires forward in an arc with no damage drop off.
 * Incendiary ammo with the Grenade Launcher is redundant unless fighting a Tank or a Witch, although Explosive Ammo will give you a slightly more potent blast. Keep in mind, however, that both upgrades will give you an extra Grenade.
 * 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.
 * 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.
 * In easy and normal difficulties, if a teammate is far from you and is pinned by a special infected, you can try kill the special infected by using this weapons. This does not apply to realism at the weapon could instantly incapacitate or kill you teammate if he is already incapacitated.

Freindly Fire
As said previously, freindly fire with this weapons is your worst enemy especially in realsim where it can instantly incapacitate a survivors or even kill him if he is already incapacitated. So training to master this weapons is required.

Videos

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