A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing, with the modern revolver being invented by Samuel Colt. As 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. The hammer-cocking happens either directly (via the shooter pulling it back) or indirectly (via the first portion of the trigger pull in double-action revolvers.) In modern revolvers, the revolving cylinder typically chambers five or six rounds, but some models hold 10 rounds or more. Revolvers are most often handguns, but other weapons may also have the design of a revolver. These include some models of grenade launchers, shotguns, and some rifles.
 
Design
 
A revolver works by having several firing chambers arranged in a circle in a cylindrical block that are brought into alignment with the firing mechanism and barrel one at a time. In contrast, other repeating firearms, such as lever-action, pump-action, and semi-automatic, have a single firing chamber and a mechanism to load and extract cartridges into it.
 
A single-action revolver requires the hammer to be pulled back by hand before each shot, which also revolves the cylinder. This leaves the trigger with just one "single action" left to perform - releasing the hammer to fire the shot - so the force and distance required to pull the trigger can be minimal. In contrast, with a self-cocking revolver, one long squeeze of the trigger pulls back the hammer and revolves the cylinder then finally fires the shot. They can generally be fired faster than a single-action, but at the cost of reduced accuracy in the hands of most shooters.
 
Most modern revolvers are "traditional double-action", which means they are able to operate either in single-action or self-cocking mode. The accepted meaning of "double-action" has, confusingly, come to be the same as "self-cocking", so modern revolvers that cannot be pre-cocked are called "double-action-only". These are intended for concealed carry, because the hammer of a traditional design is prone to snagging on clothes when drawn.
 
Most commonly, such guns have a 5- or 6-shot capacity, hence the common names of "six-gun" or "six-shooter". However, some revolvers have a 7- to 10-shot capacity, often depending on the caliber. Each chamber has to be reloaded manually, which makes reloading a revolver a much slower procedure than reloading a semi-automatic pistol.
 
The alternatives are a replaceable cylinder, a speedloader which can reload all chambers at once, or a moon clip that holds a full load (or even half of one in the case of a half-moon clip) of ammunition and that is inserted along with the ammunition. In revolvers chambered for rimless cartridges, moon clips are normally required. Another product known as a "speedstrip" cannot reload a completely empty revolver as rapidly as a speedloader, but is less expensive, flatter, and more flexible when it comes to partial reloads.
 
Compared to autoloading handguns, a revolver is often simpler to operate and may have greater reliability. For example, should a semiautomatic pistol fail to fire, clearing the chamber requires manually cycling the action to remove the errant round, as cycling the action normally depends on the energy of a cartridge firing. With a revolver, this is not necessary as none of the energy for cycling the revolver comes from the firing of the cartridge, but is supplied by the user either through cocking the hammer or, in a double action design, by just squeezing the trigger. Another significant advantage of revolvers is superior ergonomics, particularly for users with small hands. A revolver's grip is not required to accommodate a magazine, and it can be designed or customized much more than a typical semi-automatic. Partially because of these reasons, revolvers still hold significant market share as concealed carry and home-defense weapons.
 
In general, revolvers stand up to long-term neglect better than semi-automatics, an example of neglect being the common scenario of a civilian who keeps a weapon for defense but rarely shoots or maintains it. A revolver can be kept loaded and ready to fire without fatiguing any springs and is not very dependent on lubrication for proper firing. However, a revolver is generally not as resistant to abuse as a semi-automatic (abuse meaning dropping the weapon, or allowing severe contamination by dirt or mud). The revolver's clockwork-like internal parts are relatively delicate and can become misaligned after a severe impact, and its revolving cylinder can become jammed by excessive dirt or debris.
 
Over the long period of development of the revolver, many calibers have been used. Some of these have proved more durable during periods of standardization and some have entered general public awareness. Among these are the .22 rimfire, a caliber popular for target shooting and teaching novice shooters; .38 Special and .357 Magnum, known for its police use; the .44 Magnum, famous from Clint Eastwood's "Dirty Harry" films; and the .45 Colt, used in the Colt revolver of the Wild West. Introduced in 2003, the Smith & Wesson Model 500 is one of the most powerful revolvers, bested only by the .600 Nitro Express and .700 Nitro Express round. It utilizes.500 S&W Magnum.
 
Revolvers have been largely replaced by semi-automatic pistols in military and law enforcement applications. Their lower ammunition capacities and relatively longer reload times compared to autoloading pistols are the main reasons for the switchover, which occurred over the first half of the 20th century for military applications, and in the 1980s and 1990s for police forces. Additionally, the flat profile of semi-automatics make them more suitable for concealed carry. Revolvers still remain popular in the role of 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 Smith & Wesson Model 29, the Smith & Wesson Model 10, and the Smith & Wesson 1917.
 
Revolver technology does live on in other weapons used by the military. Some autocannons and grenade launchers use mechanisms similar to revolvers, and some riot shotguns use spring loaded cylinders holding up to 12 rounds. In addition to serving as backup guns, revolvers still fill the specialized niche role as a shield gun; law enforcement personnel using a "bulletproof" ballistic shield (Gun shield) sometimes opt for a revolver instead of a self-loading pistol, because the slide of a pistol may strike the front of the shield when fired. Revolvers do not suffer from this disadvantage. A second revolver may be secured behind the shield to provide a quick means of continuity of fire. Many police also still use revolvers as their duty weapon due to their relative mechanical simplicity and user friendliness.[1]
 
With the advancement of technology and design in 2010 major revolver manufacturers are coming out with polymer frame revolvers like the Ruger LCR, Smith & Wesson Bodyguard 38, and Taurus Protector Polymer. The new innovative design incorporates advanced polymer technology that lowers weight significantly, helps absorbs recoil, and strong enough to handle +P and .357 Magnum loads. The polymer is only used on the lower frame and joined to a metal alloy upper frame, barrel, and cylinder. Polymer technology is considered one of the major advancements in revolver history because the frame has always been metal alloy and mostly one piece frame design.
 
Another recent development in revolver technology is the Rhino, a revolver introduced by Italian manufacturer Chiappa in 2009 and first sold in the U.S. in 2010. The Rhino, built with the U.S. concealed carry market in mind, is designed so that the bullet fires from the bottom chamber of the cylinder instead of the top chamber as in standard revolvers. This is intended to reduce muzzle flip, allowing for faster and more accurate repeat shots. In addition, the cylinder cross-section is hexagonal instead of circular, further reducing the weapon's profile.
 
LOADING & UNLOADING
 
Front Loading
The first revolvers were front loading, and were a bit like muskets in that the powder and bullet were loaded separately. These were caplocks or "cap and ball" revolvers, because the caplock method of priming was the first to be compact enough to make a practical revolver feasible. When loading, each chamber in the cylinder was rotated out of line with the barrel, and charged from the front with loose powder and an oversized bullet. Next, the chamber was aligned with the ramming lever underneath the barrel. Pulling the lever would drive a rammer into the chamber, which sealed it and held the ball and powder securely in place. Finally, the user would place percussion caps on the nipples on the rear face of the cylinder.
 
Loading a cylinder was a slow and awkward process, so soldiers in the field often carried multiple revolvers. Some models had a removable cylinder that could be swapped quickly for a full one when emptied of rounds.
 
After each shot, a user was advised to raise his revolver vertically while cocking back the hammer so as to allow the fragments of the spent percussion cap to fall out safely. Otherwise, the fragments could fall into the revolver's mechanism and jam it.[2] Caplock revolvers were also vulnerable to "chain fires", wherein hot gas from a shot ignited the powder in the other chambers. This could be prevented by sealing the chambers with cotton, wax, or grease.
 
Fixed cylinder designs
In many of the first generation of cartridge revolvers (especially those that were converted after manufacture), the pin on which the cylinder revolved was removed, and the cylinder taken from the gun for loading. Later models used a loading gate at the rear of the cylinder that allowed one cartridge at a time to be accessed for loading, while a rod under the barrel could be pressed backwards to extract the fired case. Most revolvers using this method of loading are single-action revolvers, although Iver Johnson produced double-action models with removable cylinders. The removable-cylinder design is employed in some modern "micro-revolvers" (usually in .22 caliber), in order to simplify their design. These weapons are small enough to fit in the palm of the hand.
 
The loading gate on the original Colt designs (and on nearly all single-action revolvers since, such as the famous Colt Single Action Army) is on the right side, which may favor left-handed users; with the revolver held in the proper grip for shooting in the left hand, the cartridges can easily be ejected and loaded with the right.[3]
 
Since the cylinder in these revolvers is firmly attached at the front and rear of the frame, and since the frame is typically full thickness all the way around, fixed cylinder revolvers are inherently strong designs. Because of this, many modern large caliber hunting revolvers tend to be based on the fixed cylinder design. Fixed cylinder revolvers can fire the strongest and most powerful cartridges, but at the price of being the slowest to load and cannot use speedloaders or moon clips for loading as one chamber is exposed at a time to the loading gate.
 
Top break
The next method used for loading and unloading cartridge revolvers was the top break design. In a top-break revolver, the frame is hinged at the bottom front of the cylinder. Releasing the lock and pushing the barrel down exposes the rear face of the cylinder. In most top-break revolvers, this act also operates an extractor that pushes the cartridges in the chambers back far enough that they will fall free, or can be removed easily. Fresh rounds are then inserted into the cylinder. The barrel and cylinder are then rotated back and locked in place, and the revolver is ready to fire.
 
Top break revolvers can be loaded more rapidly than fixed-frame revolvers, especially with the aid of a speedloader or moon clip. However, this design is much weaker and cannot handle high pressure rounds. This design is mostly obsolete today, supplanted by the stronger yet equally convenient swing-out design. Nevertheless, with modern materials, Izhevsk Mechanical Plant has developed the MP412 REX, which uses the top break design
 
Swing out cylinder
The last and most modern method of loading and unloading is the swing out cylinder. The cylinder is mounted on a pivot that is coaxial with the chambers, and the cylinder swings out and down (to the left in most cases). An extractor is fitted, operated by a rod projecting from the front of the cylinder assembly. When pressed, it will push all fired rounds free simultaneously (as in top break models, the travel is designed to not completely extract longer, unfired rounds). The cylinder may then be loaded, singly or again with a speedloader, closed, and latched in place.
 
The pivoting part that supports the cylinder is called the crane; it is the weak point of swing-out cylinder designs. Using the method often portrayed in movies and television of flipping the cylinder open and closed with a flick of the wrist can in fact cause the crane to bend over time, throwing the cylinder out of alignment with the barrel. Lack of alignment between chamber and barrel is a dangerous condition, as it can impede the bullet's transition from chamber to barrel. This gives rise to higher pressures in the chamber, bullet damage, and the potential for an explosion if the bullet becomes stuck.
 
The shock of firing can also put a great deal of stress on the crane, as in most designs the cylinder is only held closed at one point, the rear of the cylinder. Stronger designs, such as the Ruger Super Redhawk, use a lock in the crane as well as the lock at the rear of the cylinder. This latch provides a more secure bond between cylinder and frame, and allows the use of larger, more powerful cartridges. Swing out cylinders are rather strong, but not as strong as fixed cylinders, and great care must be taken with the cylinder when loading, so as not to damage the crane.
 
ACTION
 
Single Action
In a single-action revolver, the hammer is manually cocked, usually with the thumb of the firing or supporting hand. This action advances the cylinder to the next round and locks the cylinder in place with the chamber aligned with the barrel. The trigger, when pulled, releases the hammer, which fires the round in the chamber. To fire again, the hammer must be manually cocked again. This is called "single-action" because the trigger only performs a single action, of releasing the hammer. Because only a single action is performed and trigger pull is lightened, firing a revolver in this way allows most shooters to achieve greater accuracy. Additionally, the need to cock the hammer manually acts as a safety.
 
Double-action
In double-action (DA), the stroke of the trigger pull generates two actions: (1) the hammer is pulled back to the cocked position while the cylinder is being indexed to the next round, and then (2) the hammer is released to strike the firing pin. Thus DA means that a cocking action separate from the trigger pull is unnecessary; and 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, but 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, that is, from a hammer-down position. In this case, the trigger first cocks the hammer and revolves the cylinder, and then trips the hammer at the rear of the trigger stroke, firing the round in the chamber.
 
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 such as Glock's. 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 or separate cocking stroke required. Although those seem simple to a person in calm circumstances, it is considered that less can go wrong with a simpler action when the user is highly stressed. This is a school of thought, not an immutable rule; some users would not make the same choice (preferring, e.g., cocked-and-locked carry), although they understand the logic.
 
Other
In the cap-and-ball days of the mid 19th century, two revolver models, the English Tranter and the American Savage “Figure Eight”, used a method whereby the hammer was cocked by the shooter’s middle finger pulling on a second trigger below the main trigger.
 
Iver Johnson made an unusual model from 1940 to 1947, called the Trigger Cocking Double Action. If the hammer was down, pulling the trigger would cock the hammer. If the trigger was pulled with the hammer cocked, it would then fire. This meant that to fire the revolver from a hammer down state, the trigger must be pulled twice.[4]
 
READ MORE AT: http://en.wikipedia.org/wiki/Revolver
 
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