Pistol

The 1911A1 pistol is mainly used as a support or emergency weapon. When a Survivor is knocked down the only weapon that can be used is the handgun, but accuracy and rate of fire are greatly diminished in this state. Pistols have an infinite ammo supply but are still limited to a 15 round magazine and still have to be reloaded.

The Pistol is actually quite accurate, especially when crouched, and can quickly and effectively dispatch common infected if aimed carefully, even at moderate ranges. Akimbo 'run and gun' tactics, however, are highly ineffective, and will merely lead to the bullets missing.

Dual-wielding
If a second pistol is found, they can be dual-wielded. Second pistols are placed periodically from the Director, and can also be picked up from fallen team mates. This allows for twice the ammo capacity, as well as a slightly faster rate of fire. The downside of having two pistols is that it takes slightly longer to reload. When dual-wielded, the pistol in the left hand will not have a light.

Another thing about the pistol is that it does about the same damage as the submachine gun, which makes it a great backup weapon. Don't be afraid to turn to the pistol(s) if your primary is out of ammo in a tight situation.

Tactics
If you are fighting a Tank or a large Horde, don't take the time to re-load your Primary Weapon. The dual-pistols are very effective. Crouch crouch crouch! Getting into a crouched position improves the accuracy of the pistol/dual pistols significantly. You'll notice this by the lines of the reticle shrinking in size and coming closer to converging at the center of your HUD. Even at medium-long ranged areas, the pistols rank right up there in terms of accuracy. Needless to say, take your pistols out for long-range as opposed to the pump/auto shotgun.Pistols are also great for taking down small groups of common infected if low on ammo for primary weapons.

If you're reloading and a teammate gets hit by a Hunter or a Smoker, quickly whip out your pistols and open fire. This will often kill the boss Infected faster than waiting for the reload, reducing the damage your buddy takes.

Trivia

 * The name "Colt" is often used as a name for generic .45 1911 pistols. However, even during the days it was first issued, Colt was far from the only manufacturer to produce them. Modern 1911s are made by a multitude of manufacturers, including Sig, Smith and Wesson, Wilson Combat, Kimber, Springfield Armory, Las Baer and Rock Island Armory.
 * The pistol is produced by the fictional company "Finleyville Armory." The name is derived from the Pennsylvania borough of Finleyville and may be meant to sound like Springfield Armory, a manufacturer of several kinds of popular 1911 pistols.
 * An actual single stack 1911 uses 7,8 or 10 round magazines. There are 1911s that hold up to 14 rounds, but they are built on double stack (where the rounds are staggered to increase capacity) frames and are quite bulky. In fact, they are more often used for competition and range shooting then actual use.
 * The setup of the 1911 in Left 4 Dead is somewhat odd: It uses stainless steel components and a fairly modern frame, with a beavertail grip safety, extended thumb safety, rounded hammer and integral light rail, but has 1911A1 style sights. The original 1911A1 stock sights are much harder to use then modern 3 dot sights, or even blade, and are almost never used on modern 1911s.


 * Players can receive the Akimbo Assassin achievement by completing a campaign using only the pistol (or pistols) as firearms.