M16 Assault Rifle

"An assault rifle. This shit's gettin more like 'Nam every second."

- Bill

The Assault Rifle is a tier 2 replacement for the Submachine Gun and Silenced Submachine Gun with higher damage and better accuracy. It holds 50 rounds with a 360 round reserve, having less total ammo than the two submachine guns, but being a better overall weapon. The assault rifle is the best choice as a general use firearm, as it is adaptable to most situations.

Tactics
The assault rifle is a weapon that is mostly effective in medium-range combat, as opposed to the short-range auto shotgun and the long-range hunting rifle. It is a very flexible weapon, however, adept at picking off Special Infected from a distance and piercing multiple Common Infected. It has quite a high piercing power, but not quite as high as the hunting rifle. Its high piercing power makes it is a useful weapon for clearing rooms full of Infected or destroying oncoming hordes. The assault rifle is also the best weapon for fighting Tanks due to the auto shotgun's damage penalty against them.

Assault rifle ammo is easy to waste. The weapon trades ammo capacity for accuracy and damage, and this must be used to full advantage to be effective. The assault rifle generally needs only two or three shots to do its job, and any more hampers its accuracy at mid to long range. Thus, burst firing or "headhunting" is highly recommended at medium to long ranges. Since all Infected run at the same height this works very well. A technique that seems to work pretty well on Xbox 360 to conserve ammo is to do a quick full trigger squeeze, which will fire 2 rounds. This can be useful when shooting long range and is effective on most difficulty settings except for expert.

The assault rifle's tighter cone of fire makes it safer than the auto shotgun when firing near other Survivors, but on higher difficulties it struggles to keep up with the increased health of the Common Infected, requiring 4 hits to kill one on Expert whereas the other tier 2 weapons only need one. Additionally, the mid-range effectiveness of the assault rifle is shared with the pistols, meaning that taking the assault rifle sacrifices some flexibility.

In a group of four on finales, it's a good idea to have two people with auto shotguns and two people with assault rifles, get in a closet or similar point which causes the Infected to file in slowly, the two people with the shotguns crouch and shoot or use melee, while the two people with the assault rifles stand behind them and fire at the Infected as they approach. This is obviously ineffective against the Tank.

Left 4 Dead 2
The assault rifle returns in Left 4 Dead 2, but has new animations.

Behind the Scenes
Early screenshots show that the assault rifle lacked text on its left side at one time.

When the assault rifle was drawn in early versions of the game, the character would pull the charging handle as soon as he took the gun out. The sound for this animation is still played when the assault rifle is drawn out in the final version of the game.

The assault rifle is based on Counter-Strike ' s M4A1 assault rifle. Its "price" in the gun's weapon file is the same as the M4A1's, and it references the M4A1 in its "animation" listing. Its firing sounds are slightly modified versions of the sounds used for the M4A1.

Trivia

 * The assault rifle is modeled after the M16A3 in Left 4 Dead and the M16A2 in Left 4 Dead 2.
 * The in-game texture states that this rifle is produced by the fictional company American Armory as the M16A2. However, it is actually based on the M16A3: the M16A2 is capable of firing in three-round bursts while the M16A3 is capable of fully automatic fire. In Left 4 Dead 2, it appears that the assault rifle is going to be changed to fix this error, as like the Combat Rifle, it will fire in 3 round bursts.
 * It has 360 reserve ammo, so it may have originally had its real life capacity of 30 rounds.
 * The M16 was the standard American weapon during the Vietnam War, of which Bill is a veteran. This explains why his AI chooses this gun whenever given the opportunity, and why he will sometimes remark, "Damn, now this takes me back!" upon doing so.