Contents of this section:
If there are terms here that are not understood, hang in there. They probably get discussed later. I've tried to organize this, but some topics seem to be circular, such that nothing can be explained until everything else has been explained. Hopefully things get clarified at the point where they become important.
Guns may be either firearms or airguns. What follows is geared toward firearms, and where I have used the term 'gun' its because I didn't feel like typing 'firearm.' The term firearm also includes alot of things that are not discussed here. Alot of what follows does apply to guns in general.
Ammunition is what is fired in a gun. A cartridge or a 'round' is one piece of ammunition.
Rifles are guns with long barrels which are intended to be held to the shoulder when fired. Handguns are usually held in one or more hands and away from the body while being fired. Pistol, can mean any handgun, but typically refers to Semi-Automatic (Self-loading) handguns rather than revolvers. A carbine is a 'handy', and relatively short barreled, rifle.
Automatic firearms, also known as machineguns, also known as "fully" automatic, begin firing when their trigger is pulled, load another round, fire that one, load another, etc. and stop when the trigger is released or the supply of ammunition is exhausted. These firearms may also be referred to as selective-fire, or select-fire, if they have a way for the operator to select either automatic or semi-automatic operation. Since automatic weapons are strictly regulated, they are relatively rare, at least in the U.S. This has lead to a laziness in using proper terminology, and when many people say 'automatic' or 'auto' what they often really mean is 'semi-automatic.'
Semi-Automatic firearms fire one shot when their trigger is pulled and immediately _prepare_ another round to be fired. Each operation of the trigger results in one cartridge being fired, and another being prepared to be fired. Only one cartridge is fired when the trigger is pulled. Pulling the trigger only fires one cartridge, even if the trigger is held in the firing position. Another round is not fired until the trigger is released and then pulled again. Some people, particularly anti-gun zealots and the popular press, have a hard time with the difference between automatic and semi-automatic. Semi-automatic pistols are often referred to as "automatic" and it is understood that they are "semi-automatic", because the term "automatic" (meaning "auto-loading") was associated with a pistol (as in Automatic Colt Pistol) before the "fully automatic" concept was around to stake a claim in the pistol terminology. For clarity, it is best to call a 'fully automatic pistol' either 'fully automatic pistol' or 'machine pistol.'
With other firearms, which are neither automatic nor semi-automatic, firing one cartridge does not immediately prepare another cartridge to be fired. Usually some other action besides pulling the trigger must be performed by the shooter. This may be the operation of a lever, a bolt, a slide, cocking a hammer, or opening the firearm to load a new cartridge. One exception to the 'some other action' rule is the double action revolver, in which the act of pulling the trigger prepares the next cartridge and the gun for firing and then fires it. This does not classify them as semi-automatic, however, because they are not prepared to fire by the firing of a previous round.
The action refers to the mechanism used to load, fire, and extract ammunition. Many different types of actions have been designed and used, and that's why you are reading this now. The action is assembled in and around a part called the receiver, if it is a rifle, or the frame, if it is a handgun.
If the design includes a moving part that opens and closes the action and at the same time loads and extracts ammunition, that part of a rifle is usually called the bolt. The analagous part of a pistol is usually called the slide.
The stock of a rifle (usually of wood) is what the shooter holds when supporting and shooting the rifle. The butt of the stock goes against your shoulder, and the forearm of the stock is supported by the non-trigger- operating support hand. Handguns are held by a part of the frame called, appropriately, the grip frame. Grips, or grip panels are usually attached to the grip frame.
The barrel is a steel tube through which bullets are fired. Modern rifles and pistols have rifled barrels which means that grooves are cut in the inside walls (the bore) which spiral down the length of the barrel. The surfaces of the bore between grooves are called lands. The purpose of the rifling (lands and grooves, collectively) is to impart a spin to the bullet so that it will be stabilized during its flight from gun to target. Shotguns and older firearms like muskets normally have smooth bores, but there are exceptions. The opening in the barrel through which the bullet departs is called the muzzle. The opening where the bullet enters is called the breech.
The chamber is where a cartridge is placed in order to be fired. Most chambers are integral parts of the breech end of the barrel. The notable exception is the revolver, which has a cylinder made with several chambers which revolves to align each chamber with the bore. The internal dimensions of the chamber and bore define what ammunition may be fired in the gun. Names of different cartridge designs for which guns are commonly available for rifles and pistols are found elsewhere in this FAQ.
The trigger is a mechanical device operated by the shooter's finger. In most designs, when the trigger is operated, a spring-loaded mechanism is allowed to fire a cartridge which has been loaded in the gun.
Some guns have a hammer, a spring loaded mechanism whose motion is used to fire the loaded cartridge when the trigger is pulled. Usually, the momentum of the hammer is transferred to the firing pin, the part which actually contacts the cartridge causing it to fire. Guns that do not have a hammer usually have what is called a striker that serves the same purpose.
A magazine is where cartridges are stored until they are loaded into the chamber. Pistols, except for revolvers, often have a removable magazine in the grip frame. Rifles normally have a magazine, which may or may not be detachable, below the action. The part of the magazine that a spring pushes against to keep cartridges in position to be fed into the chamber is called the follower. While on the subject of magazines, we should mention clips, which are not part of a firearm, but are used to hold a number of rounds of ammunition together to facilitate loading them into a firearm or magazine. The terms "clip" and "magazine" are not interchangeable, that is, magazines are not clips, and clips are not magazines, but the terms are often misused.
Sights are devices that allow the shooter to make his/her line of sight coincide approximately with the path of the bullet, so that the shooter knows where the bullet can be expected to go once it leaves the gun. Sights may be a simple post on the muzzle end of the barrel that is centered in a notch on the breech end when the shooter sights along the top of the barrel. Many variations exist and will be discussed within this FAQ eventually.
HANDGUNS (or Pistols)
Based on how they are operated, handguns can be divided into at least three classes:
1. Revolvers - As mentioned before, revolvers have a revolving cylinder with several chambers. Six chambers is the classic number, which is where the term "six-shooter" originates. Revolvers can be divided into two sub- groups: Single Action (SA) and Double Action (DA). SA revolvers require the shooter to manually cock the hammer by pulling it back until it locks in place before a cartridge can be fired by pulling the trigger. Each time the hammer is cocked, the cylinder rotates to align a chamber with the barrel. When the trigger is pulled, the hammer falls and fires the cartridge in that chamber. DA revolvers can be operated just like SA revolvers, but offer a second method of operation as well. If the hammer of a DA revolver is _not_ already cocked, then pulling the trigger will rotate the cylinder, cock the hammer, and then let the hammer fall. SA revolvers usually allow access to load or unload only one chamber at a time. DA revolvers usually allow the cylinder to swing out to the side, and all chambers can be accessed at once. Empty cartridges are pushed out of either type by a spring loaded rod called the ejector. In a DA revolver, the ejector empties all cylinders at the same time. A SA revolver requires that each chamber be aligned with the ejector individually.
2. Semi-automatic or Self-loading pistols, also often called "Automatic Pistols" use part of the energy generated by firing a cartridge to load a fresh cartridge and (usually) cock the mechanism in preparation to fire the fresh cartridge. Different designs in use today include recoil-operated, blowback-operated, and gas-operated. Most semi-automatic pistols have a slide. When the slide moves backwards, a cartridge or empty case in the chamber is pulled out of the chamber and ejected from the pistol. As the slide returns forward, it pushes a fresh cartridge out of the magazine and into the chamber. Recoil-operated pistols are operated by the momentum imparted to the slide during recoil. This design depends on the shooter to stop the backward motion of the gun frame during recoil, while the slide continues rearward. Blowback-operated pistols allow pressure in the chamber, after a cartride is fired, to force the empty cartridge and the slide rearward. Gas-operated pistols use gas pressure in front of the cartridge to move a piston connected to the slide, which moves the slide rearward. In most cases, as the slide moves to the rear, it compresses a spring. When the slide reaches its maximum rearward position the spring forces it forward again, to load the fresh cartridge. Semi-automatic pistols, like revolvers may be single-action, double action, or of some other type. The various actions are completely described elsewhere in this FAQ.
3. Other Pistols - Single-shot, bolt-action, derringers, etc.
RIFLES (or Long guns)
There is no single/double action to worry about with rifles, they would all be described as single action. But, there are a number of different mechanical designs used to operate them:
1. Bolt action rifles are operated by lifting up on a handle attached to the bolt, thus unlocking the bolt, then pulling back on the handle to remove a spent cartridge and/or open the chamber. Pushing the bolt forward again loads another cartridge from the magazine. The bolt handle is then pushed down to lock the bolt in the closed position so the cartridge can be fired. Most bolt actions cock the firing mechanism when the bolt is pulled back (cock-on-opening) but some don't cock until the action is closed (cock-on-closing.) Bolt actions are generally known as both the strongest and most accurate rifle action. The magazine of a bolt action rifle normally has the cartridges side by side on top of the follower. Bolt action rifles usually have a one piece stock.
2. Lever action rifles are operated by swinging a lever down to extract a spent cartridge and cock the hammer, and back up to load a fresh cartridge into the chamber. The magazine of a lever action rifle is often tubular, and holds the cartridges end to end. For this reason, cartridges for lever actions are loaded with flat or round nosed bullets, because a pointed nose could be damaged by, or fire, the cartridge in front of it while in the magazine.
3. Pump action rifles operate by sliding, or pumping, the forearm backward and forward. The stock of a pump action rifle is neccessarily made in two pieces.
4. Semi-automatic rifles operate much like semi-automatic pistols, discussed earlier in this section, except that a bolt opens and closes the action instead of a slide. Recoil, blowback, or gas operated designs are used, just as in pistols.
5. Single shot rifles are designed around numerous actions. Bolt actions are appropriate for use in single shot applications. Other examples are the Falling Block, in which a block moves down and up across the breech to open and close the chamber, and the Rolling Block, and Break-actions in which a piece pivots away from the breech like a door.
6. There have been a few rifles built around a handgun-like revolver action.
7. Machine guns - Stay tuned. This section will get filled in eventually.
SHOTGUNS
For the time being, at least, look in FAQ Section III.E. for info on shotguns.
A cartridge is not a bullet, but a bullet is one part of an assembled cartridge.
-For information on shotshells, refer to Section III.E.1.
Bullet - The projectile that is forced out of the cartridge, through the barrel, out of the barrel's muzzle. Bullets are often made of lead, though other materials are used. Cast bullets are made by pouring molten lead into a mold. Swaged bullets are cut or pressed out of a larger piece of lead. At muzzle velocities somewhere above 1000 ft per second, soft lead bullets may leave an unacceptable amount of lead deposits in the barrel of the firearm. To prevent this, lead bullets are usually lubricated to reduce friction. Another way to prevent leading of the barrel is to enclose the bullet in a jacket made of a harder material such as copper.
Jacketed bullets are used for other reasons as well. The forces generated when a bullet impacts a solid target can cause soft lead bullets to deform and break up. A jacketed bullet, however, can be designed to help control how the bullet behaves inside the target. Some bullets are designed with hollow points that, during penetration of the target, generate hydraulic forces causing the bullet to expand in diameter. The expanded bullet creates a larger hole in the target, but doesn't penetrate as deeply as the non-expanded bullet would because it expends its kinetic energy more rapidly than the non-expanded bullet would. The stiffness associated with the jacket material defines the velocity range in which the bullet can be expected to expand effectively. Soft point bullets (jacketed solid lead bullets with lead exposed at the nose) expand too, but not as dramatically as hollow points. Bullets completely enclosed in jacket material are also used, when it is desirable to have no deformation of the bullet in the target, allowing deep penetration.
Charge - Gun powder (black or smokeless) is used to propel the bullet through the firearm's bore. Gas is evolved when gunpowder is burned, which, in the confined space of the gun's chamber generates pressure on the base of the bullet, forcing it out of the cartridge and through the barrel. The charge is normally large enough that it continues to burn until the bullet leaves the muzzle, causing acceleration of the bullet during that entire time. A wide variety of powder compositions are available with different burning characteristics. A fast burning powder is often used in pistol applications where pressure needs to be developed quickly to impart maximum acceleration to the bullet during the short time it takes to travel down the short barrel. Conversely, best performance in rifle applications usually requires slower burning powders. Black powder and black powder substitutes usually burn more slowly than smokeless powders and generate lower peak pressures in the firearm.
Primer- Contains a small, pressure sensitive explosive held between the cup and the anvil in the case of centerfire ammunition, or distributed around the rim of the cartridge in the case of rimfire ammunition. When the cup (or rim) is struck by the gun's firing pin, the priming compound is mashed between the cup and anvil (or two sides of the rim) and detonates, igniting the charge of gun powder. Two centerfire priming systems are in use today, Berdan and Boxer. Boxer primers are made with both a cup and anvil as integral parts. Berdan primers have only a cup, and are used in cartridge cases that have an anvil as an integral part. Boxer primers come in two basic sizes, known as large and small. However, primers in each size may be designated for rifle or pistol, and standard or magnum. Berdan primers come in other sizes. They are not the same sizes. Boxer priming is most common in the U.S. where Berdan is not particularly. In some other parts of the world, the opposite is true. The chemical composition of the priming compound determines whether the ammunition is 'corrosive' or not. Some primers generate a salt as a byproduct when they are fired. If a firearm is not thoroughly cleaned after being used with corrosive ammunition, it will rust rather quickly. Although corrosive primers are more trouble to use because of the cleaning pains, consensus seems to be that they are more stable and are better candidates for long term storage than non-corrosive primers.
Case - The part of the cartridge that holds the other components together. Cases are typically made of, and sometimes referred to as brass, though other materials are used. The primer is installed in the primer pocket in the case head and ignites the powder by shooting a flame through the flash hole. The primer pockets of Boxer-primed cases typically have one flash hole in the center. The primer pockets of Berdan-primed cases usually have the anvil in the center, and a small flash hole on either side. The case head will have some form of rim or groove to aid in extraction from the gun once the cartridge has been fired. The powder charge is contained in the body of the case. Some cases have straight sided walls, while others are tapered. Still others taper more rapidly at some distance from the case head to form a shoulder and then straighten out again to form a neck (the smallest diameter section of the case.) The opening in the case where the bullet is seated is called the case mouth. Yes, the shoulder, neck and mouth are at the opposite end of the case body from the head. Doesn't make sense, but that's life. Belted cases have a raised band or belt just ahead of the extractor groove.
Here's a list of the more traditional acronyms used to describe bullet shapes and/or construction:
J is usually Jacketed. P is usually Point. S might be Soft, Semi, Spire, or Spitzer.
This is not a complete list, but you get the idea. From here you can cut and paste your favorite bullet shape, like maybe SWCHP (Semi-WadCutter Hollow Point) or JHPBTS (Jacketed Hollow Point Boat-Tailed Spitzer.)
Bullet and cartridge companies have also introduced some creative new names for bullets in an effort to distinguish their products from those of other companies. These are generally used to describe a particular product, rather than the general bullet construction. For example, Remington's Golden Sabre bullets would rightly be described as JHP (Jacketed Hollow Point), however, they have chosen to label them HPJ (High Performance Jacketed) instead. A partial listing of these fancy new acronyms includes:
which stands for: Evil Baby-Killing Death-Dealing Emergency-Room-Surgeon-Finger-Shredding Crime-Causing Flesh-Ripping Too-Dangerous-for-Average-Citizen Heat-Seeking Innocent-Bystander-Search-and-Destroy eXploding Tearing Maiming End-of- Life-As-We-Know-It Thermo-Nuclear Black Talon
which, due to an unfortunate corporate decision, was the name that these particular bullets got instead of the name 'Winchester Safety Blossoms' suggested by Chris Luchini (rec.guns Tue Nov 23 1993).
Cartridge designs are typically given names that are a combination of numerical designations and letters or words. The numbers usually describe some dimension of the bullet or case. The letters and words usually but not always indicate the person, persons, or company which developed the cartridge design. This list decyphers some of the common abbreviations and acronyms involved. A list of cartridges that are "commonly" available for revolvers is in Section III.B.1. A list of "commonly" available cartridges for semi-automatic pistols including synonymous cartridge names can be found in Section III.C.1. A list of available cartridges for rifles will appear in Section III.D.1., but was not complete at the time of this writing. Included here are one or two examples of cartridges which use each abbreviation.
Acronym or abbreviation (Examples)
Each cartridge for which firearms are chambered has a standard working pressure. Firearms chambered for a given cartridge must be able to withstand the pressure that that cartridge produces. Some modern firearms are significantly "over built", and can tolerate pressures higher than those generated by the cartridge for which they are chambered. The +P and +P+ ratings were developed to take advantage of the greater strength built into these guns.
WARNING! - Ammunition designated as +P or +P+ should not be fired in a gun without the approval of the manufacturer of the gun.
+P appended to a cartridge name, indicates that the loaded cartridge will generate pressures higher than the industry standard for that cartridge when it is fired.
+P+ appended to a cartridge name, indicates pressures even greater than those generated by +P designated ammunition will occur when fired.
+P and +P+ loads for .38 Spl. produce pressures that fall between those of standard .38 Spl and .357 Magnum, therefore, .38 Spl. ammunition designated +P and +P+ can be fired in .357 Magnum revolvers.
Here are some other acronyms that may be encountered: