Ammo

Ammo piles can be found in safe rooms and throughout chapters. They can be used to restock on ammunition for primary weapons, which include:


 * Pump shotgun
 * Submachine gun
 * Assault rifle
 * Hunting rifle
 * Auto shotgun

Tactics

 * All safe rooms have ammo piles, use this to your advantage.
 * Always make sure you have full ammo before leaving a safe room.
 * Fire at enemies while in the safe room, then restock on ammo before you leave.
 * You may want to go back to a safe room for more ammo, but only if you are close.
 * There is no point running back through half the map just for more ammo.
 * Always take more ammo if possible. Every bullet counts
 * Ammo piles will never run dry. Clear out the area ahead of the ammo, then restock.
 * Ammo is usually found near crescendo events and on longer levels.

Ammo Managment

 * The pump shotgun is likely the easiest weapon to manage. pumping means that you can easily keep track of your shells. Use pistols for medium to long ranges, or if you are a terrible shot. Don't snipe with this gun, it is not going to hit anything beyond close range.
 * The submachine gun chews up ammo like crazy. Fire in bursts at meduim to long range. 3-5 rounds per burst should be sufficient. Save full auto for large hordes, big threats like a Tank or Witch and close encounters with boss infected. Take periodic glances at your ammo count and plan how to use those remaining rounds.
 * The assault rifle follows the same general rules as the submachine gun, except the reserve is 120 rounds smaller. Increased power means that bursts of 2-4 rounds should work. Check your reserves more often than you would with the submachine gun. Continue to save full auto for those big threats.
 * The hunting rifle is the middle ground of all the weapons. The single shot, high power, and high reserve means that ammo is seldom a problem. However, the allure of rapid fire can trick many a player. It only takes one shot from this weapon to kill common infected. Reload often, and fire slowly. Use the scope for distance and accuracy. Never fire while moving. Accuracy is greatly reduced with motion. Use pistols for run and gun situations.
 * The auto shotgun is more tricky than the pump shotgun. Use tactics from all of the other weapons. Fire slowly, but effectively, keep an eye on the ammo counter, and keep the magazine topped off. save the rapid fire for tanks, witches, and hordes. Holding down the fire key will continually fire this weapon but it is slower than rapidly hitting the fire key. Use this to keep yourself from wasting shots. Like the pump shotgun, use pistols for longer ranges.

Incendiary Ammunition


The incendiary ammunition is a special type of ammo that can be found in Left 4 Dead 2. After picking up this ammo, all gun shots are flammable and can set Infected on fire (with some exceptions). Infected in hazmat suits are invulnerable to incendiary ammo. The only evidence of this at the moment is a video that can be found here showing up at about 5:49 through 6:49. The video shows an incendiary ammo pile and the effects.