keeping our gun terms straight, list of definitions

We are finally having a serious national debate on gun control, so it is important that we get our terms straight. This is not an argument one way or another, just a list of terms.

automatic, "full auto"
This is a firearm that shoots continuously when the trigger is depressed, one round after another, until the trigger is released or it runs out of ammunition. These are considered "machine guns" under Federal law and highly regulated and almost nonexistent in the civilian market. "Rounds per minute" ratings refer to full auto only. Examples include mounted machine guns, military grade M16s, M4s, AK47s, and submachine guns like the Thompson and Uzi.

semi-automatic, "auto-loading"
This is a firearm that shoots ONCE when the trigger is depressed and then loads the next round automatically. One must depress the trigger for each round fired--no continuous shooting. Examples include most handguns, civilian AR-15s, and AK variants, but also many sporting rifles and pistols. There are a few semi-auto shotguns out there too. "Automatic" in the context of a handgun means "semi-automatic." Many of the lowest cost and most common .22s are semi-auto because their construction is less expensive than bolt or lever actions.

bolt, lever, or pump action
“Action” refers to the way spent cases are ejected and new rounds are loaded. Bolt has a handle at the breech, where the cartridges are loaded near back of the barrel. When moved back by hand, the empty case is ejected. A new case is loaded when one pushes the bolt forward again. With a lever or cowboy style action one uses a lever, usually in the shape of a loop, located behind the trigger for the same purpose. Lever action rifles and shotguns are mechanically complex and expensive. With a pump, it is the same thing except the hand grip is the fore end of the shotgun (usually) or rifle (rarely). It slides forward and backward to change rounds.

handgun or pistol
Any hand-held (no shoulder stock) firearm with a barrel less than 16". Automatic pistols use the recoil of the previous shot to load the next round into the chamber for firing. They feed from a detachable magazine. Revolvers are an older design that includes a chamber for each round in a rotating, metal cylinder. Finger pressure on the trigger advances the next round into firing position. Handguns use pistol ammunition, which is short and blunt, especially for automatics where they must fit in the handle. Example, .38 Sp., .357 mag., .44 mag. for revolvers and .45acp, 9mm para., .40 S&W for auto-loaders.

rifle
Technically it is any firearm with grooved channels cut into the inside of the barrel in a spiral pattern to make the bullet spin in flight, including pistols, muskets, cannons, and shotguns. In common parlance, however, and under Federal law, it is a shoulder-mounted firearm that shoots single bullets (not a shotgun) with a barrel greater than 16". Includes military and civilian guns. Proper rifles shoot rifle bullets, which tend to be long and often pointed. Examples include .30-06, .22-250, and .30-30.

carbine
A short rifle, some of which shoot pistol ammunition.

barrel
The metal tube where bullets are accelerated from expanding gas. Federal classification often depends on the length of the barrel.

chamber
The space for the unfired round behind the barrel, ready for shooting.

machine gun
Under Federal law, it is any firearm capable of automatic fire. Historically, it refers to a mounted firearm capable of automatically shooting rifle bullets or special, large caliber machine gun bullets like .50 BMG. Machine guns are strictly regulated by Federal law and almost no civilians have them.

submachine gun
A hand or shoulder mounted automatic firearm that shoots pistol ammunition. Examples include Thompson (Tommy gun), UZI, and MP5.

shotgun
A firearm capable of shooting a number of small pellets at once. Pellet size differs among game animals ranging from very small raven pellets to relatively large 0-0 buck pellets or a single slug projectile. Generally, the larger and more dangerous the intended target, the larger and fewer the projectiles will be. Shotguns can be single shot, double shot (2 barrels), pump, lever, or semiautomatic. Shotguns and their ammunition are described in terms of gauge rather than caliber, with the large 12-gauge being the most typical.

assault rifle
A lightweight, high-capacity, short rifle capable of firing either full or semi-auto (select fire) and using shortened rifle ammunition such as 5.56mm, 7.62 Russian, or 7.62 NATO. Examples include the M16, M4, and AK47. Civilian grade (i.e., not as tough as military specifications) semi-auto only versions are NOT assault rifles, even if they look just like their military counterparts.

battle rifle
These are full sized, long rifles that take full-length rifle ammunition. They are rugged for military use and can be bolt action, semi-auto or full auto depending on when they were first issued. The USA’s main battle rifle in W.W.I was the 1903 bolt-action Springfield in .30-06. In W.W.II, it was the semi-auto M-1 Garand Springfield also in .30-06.

assault weapon
This is a term created by legislators and the news media to refer to high-capacity, military-style firearms. As it has no historic meaning, the definition is whatever the legislative authority says it is. Under the 1994 Federal Assault Weapons Ban, any semiautomatic firearm with a detachable magazine holding more than 10 rounds of ammunition was an “assault weapon.” It also greatly restricted certain accessories that Members of Congress felt were of military rather than sporting purposes. These included flash-hiders, folding stocks, and bayonets. These rules applied to any firearm regardless of caliber or basic configuration. So a high-capacity AR-15 was not allowed and neither were pistols or .22s with detachable magazines holding more than 10 rounds.

high capacity magazine
This refers to the number of rounds that a detachable magazine can hold. Be aware that not all guns use detachable magazines. There are two ways of defining this term.
The first is to apply an across the board capacity, say ten rounds, to all magazines regardless of model or caliber. Anything in excess of that is high capacity. The 1994 Federal AWB defined any magazine capable of holding more than ten rounds as high capacity and illegal for civilians. So, all auto-pistols, sporting .22s, and Ar15s were limited to 10 rounds.
The other method is to define it from the manufacturer’s perspective. Firearms are designed to hold a certain number of rounds. Those are normal capacity. Magazines that exceed those amounts are high capacity, because they exceed what is normal for that gun. The Ruger 10/22 rimfire rifle comes with a 10-round magazine that fits flush with the stock. The rifle was designed around that magazine, which is, therefore, normal for that gun. Ruger also makes a 25-round banana clip for it that sticks out of the stock several inches. It works fine, but it completely changes the ergonomics of the rifle. The 25-rounder is, therefore, high capacity.
Since many pistols are designed to hold in excess of 15 rounds and AR15s typically use 30-round magazines, gun control proponents tend to prefer the across-the-board limit rather than allowing “assault weapons” to continue using their “normal” magazines.

caliber
The diameter of either the bullet or the gun barrel expressed as decimal fractions of an inch, .38 sp, .223 Rem, .45 ACP. The letters that follow the number indicate inventing company (.308 Win for Winchester) or some specific characteristic (.357 magnum, meaning large). By convention, .36 caliber bullets are referred to as .38 as in the cases of .38 Special, .38 Super Automatic, or .380acp. If the caliber has a pair of numbers, it refers to year of first production (.30-06 from 1906) or case capacity (.45-70 for 70 grains of black gunpowder). Caliber can also be expressed in millimeters such as 7mm Mauser. If the millimeter caliber has two numbers, the second one is the length of the case. For example 9x19, a.k.a. 9mm parabellum, a.k.a. 9mm Lugar should not be confused with 9x17. Sometimes the same cartridge has inch sizes in the USA and millimeter sizes in Europe, for example .380acp and 9x17, a.k.a. 9mm Kurtz are the same round.

cartridge
In modern parlance “cartridge” implicitly means “metallic cartridge” and refers to the shell case, primer, smokeless gunpowder, and bullet all as a single unit. Sometimes they are generically called “rounds” as are plain bullets. Primers are either center fire with a priming cap in the center of the base of the casing. Otherwise they are rimfire with the priming material (mercury fulminate) around the rim of the case. Center fire is highly reliable. Rimfire is less so, but inexpensive and is reserved for very small calibers.

bullet
The projectile part of the cartridge. They are usually made of lead, though other materials are available, and covered with a copper coating. They come in a variety of shapes for various purposes.

.22LR or just “twenty-two”
0.22 Long Rifle, for rifles and handguns, is the single most common and least expensive cartridge in the world. They consist of a quarter inch wide lead slug, sometimes with a copper coating (not an actual copper jacket) at the end of a ½” copper case. To reduce costs, they are rimfire. They are slow, not powerful, and have limited accuracy. They also have very limited lethality making them unsuitable for most crimes or self defense. One can kill with a .22, but not easily. Due to their low cost, low recoil, and low noise, however, they are a favorite for recreational shooters, Olympic target shooters (the biathalon is .22), juvenile training, and very small game. The vast majority of rimfire ammunition is .22LR (there are some others) and it is its own category of ammunition (handgun, rifle, shotgun, rimfire).