Though the original name was "revolving gun", the short-hand "revolver" is universally used. (Cannons using this mechanism are known as revolver cannons.) Nearly all revolvers have six chambers in the cylinder, giving rise to the slang term "six-shooter"; however, revolvers with four to twenty chambers have been made.

The revolver allows the user to fire multiple rounds without reloading. Each time the user cocks the hammer, the cylinder revolves to align the next chamber and round with the hammer and barrel, which gives this type of firearm its name. In a single-action revolver, the user pulls the hammer back with his free hand or thumb; the trigger pull only releases the hammer. In a double-action revolver, pulling the trigger moves the hammer back, then releases it.

The first guns with multichambered cylinders that revolved to feed one barrel were made in the late 1500s in Europe. They were expensive and rare curiosities. Not until the 1800s would revolvers become practical weapons for non-rich owners. One of the first was a flintlock revolver made by Elisha Collier in 1814. The first percussion cap revolver was invented by the italian Francesco Antonio Broccu 1833. He received a prize of 300 francs for his invention, although he didn't patent it, his revolver was shown to the King Charles Albert of Sardinia. However, in 1835 a similar gun was patented by Samuel Colt. The first cartridge revolvers were produced around 1856 by Smith & Wesson.

Revolver handguns soon became standard for nearly all uses. In the early 20th century, semi-automatic pistols were developed, which can hold more rounds, and are faster to reload. "Automatic" pistols also have a flat profile, more suitable for concealed carry.

Thus automatic pistols have largely replaced revolvers in military and law enforcement use (in military use, from 1910-1960; in law enforcement, in the 1980s and 1990s).

Revolvers still remain popular as back-up and off-duty guns among American law enforcement officers and security guards. Also, revolvers are still common in the American private sector as defensive and sporting/hunting firearms. Famous police and military revolvers include the Webley, the Colt Single Action Army, the Colt Police Special, the Smith & Wesson Model 36, the Smith & Wesson Model 10, the Smith & Wesson 1917 and the Nagant M1895.

Double-action

Colt Anaconda .44 Magnum double-action revolver

In double-action (DA), the stroke of the trigger pull generates three actions:

The hammer is pulled back to the cocked position.

At the same time, the cylinder is indexed to the next round.

The hammer is released to strike the firing pin.

Thus, DA means that a cocking action separate from the trigger pull is unnecessary; every trigger pull will result in a complete cycle. This allows uncocked carry, while also allowing draw-and-fire using only the trigger. A longer and harder trigger stroke is the trade-off. However, this drawback can also be viewed as a safety feature, as the gun is safer against accidental discharges from being dropped.

Most double-action revolvers may be fired in two ways.

The first way is single-action; that is, exactly the same as a single-action revolver; the hammer is cocked with the thumb, which indexes the cylinder, and when the trigger is pulled, the hammer is tripped.

The second way is double action, or from a hammer-down position. In this case, the trigger first cocks the hammer and revolves the cylinder, then trips the hammer at the rear of the trigger stroke, firing the round in the chamber.

Unlike most DA/SA semi-automatic pistols, cocking the hammer with the thumb will give a more powerful hammer strike than cocking the hammer by pulling the trigger for most revolvers. This is due to the trigger design on revolvers. Manually cocking the hammer moves the hammer back to the point where it catches on the sear. Pulling the trigger when the hammer is not cocked moves the hammer back by means of a strut, or some other mechanism, which does not pull as far back, and ultimately does not give the hammer as much rearward travel as manual cocking. The greater rearward travel afforded by manual cocking translates to greater force in the hammer fall.

Enfield No. 2 Mk I* double-action-only revolver. Note the spurless hammer.

Certain revolvers, called double action only (DAO) or, more correctly but less commonly, self cocking, lack the latch that enables the hammer to be locked to the rear, and thus can only be fired in the double action mode. With no way to lock the hammer back, DAO designs tend to have bobbed or spurless hammers, and may even have the hammer completely covered by the revolver's frame (i.e., shrouded or hooded). These are generally intended for concealed carrying, where a hammer spur could snag when the revolver is drawn. The potential reduction in accuracy in aimed fire is offset by the increased capability for concealment.

DA and DAO revolvers were the standard-issue sidearm of countless police departments for many decades. Only in the 1990s did the semiautomatic pistol begin to make serious inroads after the advent of safe actions. The reasons for these choices are the modes of carry and use. Double action is good for high-stress situations because it allows a mode of carry in which "draw and pull the trigger" is the only requirement-no safety catch release nor separate cocking stroke is required. Although those actions may seem simple to a person in calm circumstances, it[according to whom?] is considered that less can go wrong with a simpler action when the user is highly stressed.

King of the Double Actions