Chainsaw

"And if we run out of bullets.... Baby, they gonna wish we hadn't!"

"DIE, DIE, DIE MY DARLINS!!!! DIE, DIE, DIE!!!"

"YEEEEEAAAHH!!!!"

The Chainsaw is a close combat weapon introduced in Left 4 Dead 2. When used, it is held out in front of the Survivor, dealing heavy damage to any Infected in it's way and giving the worst injuries to Common Infected by far. However, the Chainsaw runs out of gas after about one minute of continuous usage, causing the Survivor to drop it and pull out a P220 Pistol. A Survivor can not refill the Chainsaw.

Unlike other secondary weapons, the Chainsaw is a rather rare find, usually spawning out of the way, normally in the same areas that the Grenade Launcher can be found. The Chainsaw takes up a rather large area of the screen when out and a larger area when spinning, and does a lot of friendly fire damage, even on normal.

When a Survivor is using the Chainsaw, Common Infected are attracted to them. Against most Special Infected, it's usually best to use your primary weapon, although you can kill a stationary Witch with the Chainsaw before she can get up and strike you, or warn off Hunters and Jockeys by firing it in place, causing them damage should they attempt to pounce you.

Tactics

 * The Chainsaw's long rev-up time means that switching to it in the middle of a horde is a bad idea. Instead, find some cover before pulling it out. It also makes it a poor secondary weapon, given most melee weapons are more of a last resort (unless the player is working on certain achievements), and time spent switching to one is time not used cracking skulls.
 * When covered in Boomer bile, the Chainsaw is a good option to rip through the incoming horde. However, the bile also makes it more difficult to watch for your teammates, so be careful.
 * Keep your distance from other Survivors when using the Chainsaw so that you can avoid hurting them and make it easier for them to shoot Common Infected attracted to you.
 * When using the Chainsaw, it's usually best to pick up a primary weapon with good range, such as an Assault Rifle or Sniper Rifle, for taking out Special Infected.
 * A Bile bomb works well with the Chainsaw, making it easy to line up Infected for kills.
 * The chainsaw has limited fuel, so make sure your other weapon has ammo.
 * A deadly perk is a grenade launcher and a chainsaw.
 * The chainsaw is the only melee weapon that will allow you to free yourself from a smoker's tongue (only while being grabbed by it, not after you are completely tied up)

Trivia

 * The Chainsaw is modeled after the line of STiHL chainsaws.
 * The Chainsaw is a fairly common weapon of find at the first levels of Dead Center and Swamp Fever. There are hardly any chainsaws in other campaigns, though you may find one.
 * The Chainsaw seems to be Coach's signature weapon, as seen in the trailers, in the intro, and in Coach's bio.
 * CPU players will never pick up or use the Chainsaw. If someone takes a break while using the Chainsaw, the computer will drop it.
 * Oddly enough, if you pick up the Chainsaw in Commentary Mode, all nearby Infected suddenly become hostile and attack.
 * A rare glitch in the Xbox 360 version causes the top halves of Common Infected to float in the air with their entrails swinging around beneath them.
 * If you look at the chainsaw in the E3 trailer, you can see what looks like: '22" HALE PRO'. "HALE" may be a reference to Saxton Hale from Team Fortress 2.
 * Ellis' line 'DIE DIE DIE MY DARLINGS' is likely a reference from the song 'Die, Die My Darling' by the Misfits. This would make sense given that this particular band had something of an obsession with the novel 'American Psycho' by Bret Easton Ellis, which contained a large amount of scenes featuring the violent use of a chainsaw to mutilate victims.
 * The Chainsaw can kill Riot Infected from the front.