Pistol

The M1911A1 Pistol is the backup weapon of all Survivors. It is also the only weapon they can use when knocked down, although with a slower rate of fire and greatly decreased accuracy. Besides the minigun, the pistol(s) is the only weapon that has infinite ammunition. However, they are still limited to a magazine capacity of 15 rounds. Even though they are meant as emergency weapons, the pistols make great secondaries, or even primaries for hunting rifle and shotgun users. They pack a punch slightly greater than that of the assault rifle, and possess above average accuracy.

Pistols will usually spawn on the first level of each campaign. This occurs most frequently on easy and normal. However, on advanced and expert, they are often not available during the first level.

It is only possible to unlock the achievement "Akimbo Assassin" by completing an entire campaign using pistols.

Dual-wielding
If a second pistol is found, they can be dual-wielded. Second pistols are placed periodically by the Director, and can also be picked up from fallen teammates. This allows for twice the ammo capacity, as well as the rate of fire being increased from 300 RPM to 600 RPM. The downside of having two pistols is that it takes slightly longer to reload, but the extra damage and rounds are worth it. When dual-wielded, the pistol in the left hand will not have a light.

This makes achieving "Akimbo Assassin" much easier, due to repeated mashing of the fire button causing a 600 RPM wave of bullets. Dual pistols also carry over to the Incapacitated status, making it easier to hold off infected attacking a downed Survivor yet making it longer to reload.

Tactics

 * Pistols can be quite effective in the right hands. However, to be an effective pistol user, you must be accurate; try to crouch when the situation permits, as it will tighten your crosshairs and accuracy.
 * The pistols have great accuracy, and a pistol user must take advantage of this. When using a pump shotgun or auto shotgun, it is a good idea to use pistols for distant targets, as shotguns are bad at long range.
 * When using the hunting rifle, it is advantageous to use pistols while running, as the hunting rifle is not as good while running.
 * In certain situations, switching to pistols may be a better option than waiting for your reload.
 * If a distant teammate is disabled by a Hunter or a Smoker and your magazine is empty, then draw your pistols and open fire. This will probably kill the Special Infected faster than if you were to reload, reducing the damage taken by your teammate.
 * Pistols have unlimited ammo, so switching to them will conserve your primary ammo for more dangerous situations, such as a horde or Tank.
 * The faster you click the mouse/press the trigger to fire, the faster the pistol fires. However, it's not automatic, so holding the button down does nothing.
 * Like any other weapon, try to keep your pistols fully loaded even when you're not using them, as they are your only resort if you are to become unexpectedly incapacitated.

Left 4 Dead 2
In Left 4 Dead 2, there will be at least three different pistols—Glock 17, SIG Sauer P220 and a magnum. Only the first two pistols can be dual-wielded, but they can be combined in any way when wielding double pistols.

In one of the footage videos of the Left 4 Dead 2 beta, it has been seen that one of the pistols fires as an automatic weapon. It is unknown if it is the submachine gun that has the full-auto capability or a pistol.

Currently, the pistols are replaced by a melee weapon when one is picked up. When a Survivor goes down with a melee weapon, they draw at least one pistol as usual, but it is unknown if another pistol must otherwise be picked up or if the melee weapon can be dropped freely still.

Behind the Scenes
Originally, the pistols had limited ammo. It appears that you were able to hold 260+ maximum rounds in addition to the rounds loaded in them. This was scrapped and replaced with infinite ammo.

At one time, when dual-wielding pistols, both pistols had a flashlight on them. This can be seen on the Intro Scene, where both of Zoey's pistols have flashlights attached. It is likely that the Intro Scene was made before the decision to remove the other flashlight was made.

The pistol is based on Counter-Strike's USP .45 pistol's programming. Its "price" in the gun's weapon file is the same as the USP's.

Trivia

 * 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 (which is what the in game model is based off of) 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 than actual use.
 * The set-up 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 than modern 3 dot sights, or even blade, and are almost never used on modern 1911s.
 * Although when wielding dual pistols in-game the left-hand pistol does not have a flash light attached, in the opening cutscene, both of Zoey's pistols have flashlights attached.
 * The P220 in Left 4 Dead 2 doesn't have a walking animation, it stays completely still on your screen.
 * Each survivor has a holster on their thigh, but when a second pistol is picked up, there is not an extra holster anywhere visable. Upon being incapacitated, however, it looks like the second pistol is pulled from the right side of their upper torso, implying there is, in fact, a less or non-visable holster near their armpit.