Caliber
Encyclopedia
In guns
Güns
Güns or Guens may refer to:* Kőszeg, Hungary * Kőszeg Mountains, Hungary * Akiva Güns , birth name of Akiva Eger, a Hungarian-Polish rabbi- See also :* Guns * Gün, a surname...

 including firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...

s, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it.

In a rifled
Rifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...

 barrel
Gun barrel
A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....

, the distance is measured between opposing lands or grooves; groove measurements are common in cartridge designations originating in the United States, while land measurements are more common elsewhere. It is important to performance that a bullet should closely match the groove diameter of a barrel to ensure a good seal. When the barrel diameter is given in inches, the abbreviation "cal" is used in place of "inches." For example, a small bore rifle with a diameter of 0.22 inch is a .22 cal; however, the decimal point is generally dropped when spoken, making it "twenty-two caliber" or a "two-two caliber". Calibers of firearms can be referred to in millimeters, as in a "caliber of eighty-eight millimeters" (88 mm) or "a hundred and five-millimeter caliber gun" (often abbreviated as "105 mm gun").

While modern cartridges and cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...

 firearms are generally referred to by the cartridge name, they are still lumped together based on bore diameter. For example, a firearm might be described as a ".30 caliber rifle", which could be any of a wide range of cartridges using a roughly .30 inch projectile; or a ".22 rimfire", referring to any rimfire
Rimfire ammunition
A rimfire is a type of firearm cartridge. It is called a rimfire because instead of the firing pin of a gun striking the primer cap at the center of the base of the cartridge to ignite it , the pin strikes the base's rim....

 cartridge using a .22 caliber projectile.

In some contexts, e.g. guns aboard a warship, "caliber" is used to describe the barrel length as multiples of the bore diameter. A "5-inch 50 caliber" gun has a bore diameter of 5 inches (127 mm) and a barrel length of 50 times 5 inches = 250 inches (6.35 m).

Cartridge naming conventions

Makers of early cartridge arms had to invent methods of naming the cartridges, since there was at the time no established convention. One of the early established cartridge arms was the Spencer repeating rifle
Spencer repeating rifle
The Spencer repeating rifle was a manually operated lever-action, repeating rifle fed from a tube magazine with cartridges. It was adopted by the Union Army, especially by the cavalry, during the American Civil War, but did not replace the standard issue muzzle-loading rifled muskets in use at the...

, which saw service in the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

. It was named based on the chamber dimensions, rather than the bore diameter, with the earliest cartridge called the "No. 56 cartridge," indicating a chamber diameter of .56 inch; the bore diameter varied considerably, from .52 to .54 inch. Later various derivatives
Wildcat cartridge
A wildcat cartridge, or wildcat, is a custom cartridge for which ammunition and firearms are not mass produced. These cartridges are often created in order to optimize a certain performance characteristic of an existing commercial cartridge.Developing and using wildcat cartridges does not...

 were created using the same basic cartridge but with smaller diameter bullets; these were named by the cartridge diameter at the base and mouth. The original No. 56 became the .56-56, and the smaller versions, .56-52, .56-50, and .56-46. The .56-52, the most common of the new calibers, used a .50 caliber bullet.

Other early white powder-era (Ballistite
Ballistite
Ballistite is a smokeless propellant made from two high explosives, nitrocellulose and nitroglycerine. It was developed and patented by Alfred Nobel in the late 19th century.-The development of smokeless powders:...

 and Poudre blanche
Poudre B
Poudre B : was the first practical smokeless gunpowder. Originally called "Poudre V" from the name of the inventor, Paul Vieille, it was later renamed "Poudre B" to distract German espionage...

) cartridges used naming schemes that appeared similar, but measured entirely different characteristics. .45-70
.45-70
The .45-70 rifle cartridge, also known as .45-70 Government, was developed at the U.S. Army's Springfield Armory for use in the Springfield Model 1873...

, .38-40, and .32-20 were designated by bullet diameter in hundredths of an inch and standard black powder charge in grain
Grain (measure)
A grain is a unit of measurement of mass that is nominally based upon the mass of a single seed of a cereal. From the Bronze Age into the Renaissance the average masses of wheat and barley grains were part of the legal definition of units of mass. However, there is no evidence of any country ever...

s. Optionally the bullet weight in grain
Grain (measure)
A grain is a unit of measurement of mass that is nominally based upon the mass of a single seed of a cereal. From the Bronze Age into the Renaissance the average masses of wheat and barley grains were part of the legal definition of units of mass. However, there is no evidence of any country ever...

s was designated, e.g. .45-70-405. This scheme was far more popular and was carried over after the advent of early smokeless powder
Smokeless powder
Smokeless powder is the name given to a number of propellants used in firearms and artillery which produce negligible smoke when fired, unlike the older gunpowder which they replaced...

 cartridges such as the .30-30Short
.30-30 Winchester
The .30-30 Winchester/.30 Winchester Center Fire/7.62×51mmR cartridge was first marketed in early 1895 for the Winchester Model 1894 lever-action rifle. The .30-30 , as it is most commonly known, was the USA's first small-bore, sporting rifle cartridge designed for smokeless powder. The .30-30 is...

 and .22 Long
.22 Long
.22 Long is a variety of .22 caliber rimfire ammunition. The .22 Long is the second oldest of the surviving rimfire cartridges, dating back to 1871, when it was loaded with a 29 grain bullet and 5 grains of black powder, 25% more than the .22 Short it was based on...

; or a relative power, such as .44 Special
.44 Special
The .44 Special or .44 S&W Special is a smokeless powder center fire metallic cartridge developed by Smith & Wesson in 1907 as the standard chambering for their New Century revolver, introduced in 1908.-Development history:...

 and .44 Magnum
.44 Magnum
The .44 Remington Magnum, or simply .44 Magnum, is a large-bore cartridge originally designed for revolvers. After introduction, it was quickly adopted for carbines and rifles...

. Variations on these methods persist today, with new cartridges such as the .204 Ruger
.204 Ruger
The .204 Ruger is a centerfire rifle cartridge developed by Hornady and Ruger. At the time of its introduction in 2004, the .204 Ruger was the highest velocity commercially produced ammunition, and the only cartridge produced commercially for bullets of .204 inch/5 mm caliber.-Characteristics:The...

 and .17 HMR
.17 HMR
.17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by the ammunition company Hornady in 2002. It descended from the .22 Magnum by necking down the .22 Magnum case to take a .17 caliber bullet, and it is more costly to shoot than traditional .22...

 (Hornady Magnum Rimfire).

Metric calibers for small arms are usually expressed with an "x" between the width and the length; for example, 7.62x51 NATO. This indicates that the cartridge uses a 7.62 mm diameter bullet, loaded in a case 51 mm long. Similarly, the 6.5x55 Swedish cartridge has a bullet diameter of 6.5 mm and a case length of 55 mm. To convert from the diameter in mm to caliber divide the mm diameter by 25.4. If you want to convert from caliber to mm you multiply by 25.4. The means of measuring a rifled bore varies, and may refer to the diameter of the lands or the grooves of the rifling; this is why the .303 British
.303 British
.303 British, or 7.7x56mmR, is a .311 inch calibre rifle and machine gun cartridge first developed in Britain as a blackpowder round put into service in December 1888 for the Lee-Metford rifle, later adapted to use smokeless powders...

, measured across the lands, actually uses a .311 inch bullet (7.70 mm vs. 7.90 mm), while the .308 Winchester
.308 Winchester
The .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...

, while dimensionally similar to (but should not be considered interchangeable with) the 7.62x51 mm NATO cartridge, is measured across the grooves and uses a .308" diameter (.308 times 25.4 = 7.82 mm) bullet. An exception to this rule are the proprietary cartridges used by U.S. maker Lazzeroni
Lazzeroni
John Lazzeroni is a US sporting firearms and cartridges designer and manufacturer. Lazzeroni Arms Company is based in Tucson, Arizona. See Lazzeroni rifles and Lazzeroni cartridges....

, which are named based on the groove diameter in millimeters, such as the 7.82 Warbird.

Modern small arms range in bore size from approximately .17 (4.5 mm) up to .50 caliber (12.7 mm). Arms used to hunt large dangerous game, such as those used in express rifle
Express rifle
The term express was first applied to hunting rifles and ammunition beginning in the middle 19th century, to indicate a rifle or ammunition capable of higher than typical velocities. The early express cartridges used a heavy charge of black powder to propel a lightweight, often hollow point...

s, may be as large as .80 caliber. In the middle of the 19th century, musket
Musket
A musket is a muzzle-loaded, smooth bore long gun, fired from the shoulder. Muskets were designed for use by infantry. A soldier armed with a musket had the designation musketman or musketeer....

s and muzzle-loading rifle
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...

s were .58 caliber or larger; the Brown Bess
Brown Bess
Brown Bess is a nickname of uncertain origin for the British Army's Land Pattern Musket and its derivatives. This musket was used in the era of the expansion of the British Empire and acquired symbolic importance at least as significant as its physical importance. It was in use for over a hundred...

 flintlock
Flintlock
Flintlock is the general term for any firearm based on the flintlock mechanism. The term may also apply to the mechanism itself. Introduced at the beginning of the 17th century, the flintlock rapidly replaced earlier firearm-ignition technologies, such as the doglock, matchlock and wheellock...

, for example, had a bore diameter of about .75 caliber (19 mm). Paintball
Paintball
Paintball is a sport in which players compete, in teams or individually, to eliminate opponents by tagging them with capsules containing water soluble dye and gelatin shell outside propelled from a device called a paintball marker . Paintballs have a non-toxic, biodegradable, water soluble...

 guns (or "markers") are typically .68 caliber (17 mm).

Metric versus Imperial

The following table lists some commonly used calibers with their metric and imperial equivalents. Due to variations in naming conventions, and the whims of the cartridge manufacturers, bullet diameters can vary widely from the diameter implied by the name. For example, there is a difference of as much as 0.045 inches (1.15 mm) between the smallest and largest of the several cartridges designated as '.38 caliber'. And it may be noted that .38 inches is more than 9 1/2 mm.
Common calibers in inch and their metric equivalents
Caliber Metric equivalent Typical bullet diameter Common cartridges Notes
.17 4.4 mm
4 mm caliber
This article lists firearm cartridges which have a bullet in the .172 in / 4.5mm caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge.All measurements are in mm .-Rimfire cartridges:...

 
0.172 in .17 Remington
.17 Remington
The .17 Remington was introduced in 1971 by Remington Arms Company for their model 700 rifles.It is based on the .223 Remington, necked down to .172in , with the shoulder moved back. It was designed exclusively as a varmint round, though it is suitable for smaller predators. There are those such as...

, .17 HMR
.17 HMR
.17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by the ammunition company Hornady in 2002. It descended from the .22 Magnum by necking down the .22 Magnum case to take a .17 caliber bullet, and it is more costly to shoot than traditional .22...

 
.177 4.5 mm
4 mm caliber
This article lists firearm cartridges which have a bullet in the .172 in / 4.5mm caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge.All measurements are in mm .-Rimfire cartridges:...

 
.177 lead, .175 BB Airgun .177 caliber
.20, .204 5 mm
5 mm caliber
This article lists firearm cartridges which have a bullet in the to caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge.All measurements are in mm .-Rimfire cartridges:...

 
0.204 in .204 Ruger
.204 Ruger
The .204 Ruger is a centerfire rifle cartridge developed by Hornady and Ruger. At the time of its introduction in 2004, the .204 Ruger was the highest velocity commercially produced ammunition, and the only cartridge produced commercially for bullets of .204 inch/5 mm caliber.-Characteristics:The...

, 5 mm Remington Rimfire Magnum
5 mm Remington Rimfire Magnum
The 5 mm Remington Rimfire Magnum is an obsolete bottlenecked rimfire cartridge introduced by Remington Arms Company in 1970. Remington chambered it in a pair of bolt-action rifles, the Model 591 and Model 592, but the round never became very popular, and the rifles were discontinued in 1974....

.22, .218, .219 .220, .221, .222, .223, .224, .225, .226 5.5, 5.56, 5.7 mm 0.223-0.224 in .22 Long Rifle
.22 Long Rifle
The .22 Long Rifle rimfire cartridge is a long established variety of ammunition, and in terms of units sold is still by far the most common in the world today. The cartridge is often referred to simply as .22 LR and various rifles, pistols, revolvers, and even some smoothbore shotguns have...

, .222 Remington
.222 Remington
The .222 Remington aka the Triple Deuce/Triple Two/Treble Two is a centerfire rifle cartridge introduced in 1950, and was the first commercial rimless .22 cartridge made in the United States...

, .223 Remington
.223 Remington
The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56×45mm NATO military cartridge. The name is commonly pronounced either two-two-three or two-twenty-three. It is loaded with a diameter, jacketed bullet, with weights ranging from , though the most common...

 (5.56mm NATO), 5.7 x 28 mm, .22-250 Remington
.22-250 Remington
The .22-250 Remington is a very high-velocity , short action, .22 caliber rifle cartridge primarily used for varmint hunting and small game hunting, though it finds occasional use on deer. This cartridge is also sometimes known as the 22 Varminter or the 22 Wotkyns Original Swift...

, .22 Airgun 
NATO Round, M4/M16
.228 none 0.228 in .228 Ackley Magnum Bullets formerly available from Barnes, in heavily constructed 70 and 90 grain weights for medium game use
.24 6 mm
6 mm caliber
This article lists firearm cartridges which have a bullet caliber between and .*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge.All measurements are in mm .-Pistol cartridges:-.24in :...

 
0.243 in .243 Winchester
.243 Winchester
The .243 Winchester is a popular sporting rifle cartridge. Initially designed as a varmint round, it is now more frequently used on medium to large game such as whitetail deer, mule deer, pronghorn, wild hogs, and even black bear and caribou...

, 6 mm Remington
6 mm Remington
The 6mm Remington was introduced by Remington Arms Company in 1955 as the .244 Remington. It is based on necking down the .257 Roberts. Originally intended as a Varmint and predator cartridge, the .244 was never factory loaded with bullets over 90 grains. Rifles marked .244 Remington have a 1 in ...

, 6mm plastic airsoft BBs
.25 6.35 mm 0.25 in, 6.35 mm .25 ACP
.25 ACP
The .25 ACP centerfire pistol cartridge is a semi-rimmed, straight-walled pistol cartridge introduced by John Browning in 1905 alongside the Fabrique Nationale model 1905 pistol...

, 6.35x16mmSR
a.k.a .25 Auto and 6.35 mm Browning
.257 6.5 mm 0.257 in, 6.527 mm .257 Roberts
.257 Roberts
The .257 Roberts a medium powered .25 caliber cartridge known affectionately as the Bob. It has been described as the best compromise between the low recoil and flat trajectory of smaller calibers such as the .22 and 6mm, and the strong energy but not the strong recoil of larger popular hunting...

, .25-06 Remington
.25-06 Remington
The .25-06 Remington had been a wildcat cartridge for half a century before being standardized by Remington in 1969. It is based on the .30-06 Springfield cartridge necked-down to .257 inch caliber with no other changes...

, .250 Savage 
typical 25 cal, not normally called 6.5
.26 6.5 mm 0.264 in, 6.7 mm 6.5 x 55 mm
6.5 x 55 mm
6.5×55mm or 6.5×55mm SE is a rifle cartridge developed in 1891 for use in the new rifles then under consideration by the Swedish-Norwegian Kingdom. The two nations had independent armies...

, .260 Remington
.260 Remington
The .260 Remington cartridge was introduced by Remington in 1997. Many wildcat cartridges based on the .308 Winchester case had existed for years before Remington standardized this round...

 
cartridges commonly known as 6.5
.27 6.8 mm, 7 mm 0.277 in, 7.035 mm .270 Winchester
.270 Winchester
The .270 Winchester was developed by Winchester Repeating Arms Company in 1923 and unveiled in 1925 as a chambering for their bolt-action Model 54. The cartridge is based upon the .30-06 Springfield...

, 6.8 SPC 
not called 7 mm
.28 7 mm
7 mm caliber
This article lists firearm cartridges which have a bullet in the to caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge....

 
0.284 in, 7.213 mm 7 mm Remington Magnum
7 mm Remington Magnum
The 7mm Remington Magnum rifle cartridge was introduced as a commercially available round in 1962, along with the new Remington Model 700 bolt action rifle. It is a member of the belted magnum family that is directly derived from the venerable .375 H&H Magnum...

, 7 x 57 mm
7 x 57 mm Mauser
The 7×57mm cartridge, also known as the 7 mm Mauser, 7×57mm Mauser, 7 mm Spanish Mauser in the USA and .275 Rigby in the United Kingdom, was developed by Paul Mauser of the Mauser company in 1892 and adopted as a military cartridge by Spain in 1893. It was subsequently adopted by several...

, 7mm-08 Remington 
commonly called 7 mm
.30 7.82 mm 0.308 in 30-06
.30-06 Springfield
The .30-06 Springfield cartridge or 7.62×63mm in metric notation, was introduced to the United States Army in 1906 and standardized, and was in use until the 1960s and early 1970s. It replaced the .30-03, 6 mm Lee Navy, and .30 US Army...

, .308 Winchester
.308 Winchester
The .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...

  (7.62mm NATO), .300 Winchester Magnum
.300 Winchester Magnum
The .300 Winchester Magnum is a popular, belted, bottlenecked magnum rifle cartridge that was introduced by Winchester Repeating Arms Company in 1963 as a member of the family of Winchester Magnum cartridges. The .300 Winchester Magnum is a magnum cartridge designed to fit in a standard length...

 
American ".30 caliber"
.30 7.62 mm 0.311 in .303 British
.303 British
.303 British, or 7.7x56mmR, is a .311 inch calibre rifle and machine gun cartridge first developed in Britain as a blackpowder round put into service in December 1888 for the Lee-Metford rifle, later adapted to use smokeless powders...

, 7.62x39, 7.62x54R
Other ".30 caliber"
.32, .327 7.65 mm 0.309 - 0.312 in .32 ACP
.32 ACP
.32 ACP , also known as the .32 Automatic is a pistol cartridge. It is a semi-rimmed, straight-walled cartridge developed by firearms designer John Browning, initially for use in the FN M1900 semi-automatic pistol...

, .32 S&W
.32 S&W
The .32 S&W cartridge was introduced in 1878 for the Smith & Wesson model 1½ revolver. It was originally designed as a black powder cartridge.The .32 S&W was offered to the public as a light, defense cartridge, for "card table" distances....

, .327 Federal Magnum
.327 Federal Magnum
The .327 Federal Magnum is a cartridge introduced by Sturm, Ruger and Federal Cartridge, intended to provide the power of a .357 Magnum in six shot, compact revolvers, whose cylinders only hold 5 rounds of the larger .357 Magnum cartridge...

 
.32 caliber handgun cartridges
.32, .325 8 mm
8 mm caliber
This article lists firearm cartridges which have a bullet in the to caliber range.*Length refers to the empty cartridge case length.*OAL refers to the overall length of the loaded cartridge.All measurements are in mm .-Pistol cartridges:...

 
0.323 in 8x57mm IS, .325 WSM
.325 WSM
.325 Winchester Short Magnum is an 8 mm caliber rebated rim bottlenecked centerfire short magnum cartridge that was introduced in 2005 by Winchester...

, 8 mm Remington Magnum
8 mm Remington Magnum
The 8mm Remington Magnum belted rifle cartridge was introduced by Remington Arms Company in 1978 as a new chambering for the model 700 BDL rifle. The 8 mm Remington Magnum's parent case is the .375 H&H Magnum...

, 8mm plastic (airsoft) BBs
.32 caliber rifle cartridges
.338 8.58 mm 0.338 in .338 Lapua
.338 Lapua
The .338 Lapua Magnum is a specialized rimless bottlenecked centerfire cartridge developed for military long-range sniper rifles. The Afghanistan War and Iraq War made it a combat-proven round with ready and substantial ammunition availability...

, .338 Winchester Magnum
.338 Winchester Magnum
The .338 Winchester Magnum is a .33 caliber belted rimless bottlenecked cartridge introduced in 1958 by Winchester Repeating Arms Company|Winchester. It is based on the blown out, shortened .375 H&H Magnum. The .33 is the caliber at which medium bore cartridges are considered to begin...

, .338 Federal
.338 Federal
The .338 Federal is a rifle cartridge based on the .308 Winchester case necked up to .33 caliber. It was created by Federal Cartridge and Sako in 2006 and intended as a big game cartridge with reasonable recoil for lightweight rifles.-Comparison:...

 
.338 Rifle cartridge
.38, .380, .357, .35 9 mm
9 mm caliber
This article lists firearm cartridges which have a bullet in the caliber range. The most prevalent of these rounds is the 9x19mm Parabellum.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge....

 
0.355-0.357 in .38 Special
.38 Special
The .38 Smith & Wesson Special is a rimmed, centerfire cartridge designed by Smith & Wesson. It is most commonly used in revolvers, although some semi-automatic pistols and carbines also use this round...

, .380 ACP
.380 ACP
The .380 ACP pistol cartridge is a rimless, straight-walled pistol cartridge developed by firearms designer John Browning. The cartridge headspaces on the mouth of the case. It was introduced in 1908 by Colt, and has been a popular self-defense cartridge ever since...

, .357 Magnum
.357 Magnum
The .357 S&W Magnum , or simply .357 Magnum, is a revolver cartridge created by Elmer Keith, Phillip B. Sharpe, Colonel D. B. Wesson of firearms manufacturer Smith & Wesson, and Winchester. It is based upon Smith & Wesson's earlier .38 Special cartridge. The .357 Magnum cartridge was introduced in...

, .357 SIG
.357 SIG
The .357 SIG pistol cartridge is the product of Swiss-German firearms manufacturer SIG-Sauer, in cooperation with the American ammunition manufacturer Federal Cartridge. While it is based on a .40 S&W case necked down to accept bullets, the .357 SIG brass is slightly longer...

, .35 Remington
.35 Remington
The .35 Remington is the only remaining cartridge from Remington's lineup of medium power rimless cartridges still in commercial production. Introduced in 1906, it was originally chambered for the Remington Model 8 semi-automatic rifle in 1908.-History:...

, 9×19mm Parabellum, 9x18mm Makarov 
Generally .357 for revolvers and rifles, .355 in autoloaders,
.38 10 mm
10 mm caliber
This article lists firearm cartridges which have a bullet in the caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge.All measurements are in mm .-Pistol cartridges:...

 
0.400 in .38-40  Old black powder cartridge
.40 10 mm 0.400 in .40 S&W
.40 S&W
The .40 S&W is a rimless pistol cartridge developed jointly by major American firearms manufacturers Winchester and Smith & Wesson. The .40 S&W was developed from the ground up as a law enforcement cartridge designed to duplicate performance of the FBI's reduced velocity 10mm cartridge which could...

, 10 mm Auto
10 mm Auto
The 10mm Auto is a semi-automatic pistol cartridge developed by Jeff Cooper and introduced in 1983 for the Bren Ten pistol. It was initially produced by ammunitions manufacturer FFV Norma AB of Åmotfors, Sweden.Although it was selected by the F.B.I. for use in the field following the 1986 F.B.I...

 
.404 10.25 mm 0.423 in .404 Jeffery
.404 Jeffery
The .404 Jeffery is a large caliber, rimless cartridge designed for large, dangerous game, such as the big five of Africa. Other names for this cartridge include .404 Jeffery Rimless, .404 Rimless Nitro Express, and 10.75 × 73 mm...

 
.405 10.75 mm 0.411 in .405 Winchester
.405 Winchester
The .405 Winchester is a centerfire rifle cartridge introduced in 1904 for the Winchester 1895 lever-action rifle. It was the most powerful lever-action cartridge available until the .444 Marlin was introduced in 1964, and was highly regarded by U.S. President Theodore Roosevelt during his safari...

 
.408 10.4 mm 0.408 in .408 Chey Tac
.408 Chey Tac
The .408 Cheyenne Tactical is a specialized rimless, bottlenecked, centerfire cartridge for military long-range sniper rifles that was developed by Dr. John D. Taylor and machinist William O. Wordman...

CheyTac Intervention
CheyTac Intervention
The CheyTac Intervention is an American bolt action sniper rifle manufactured by CheyTac LLC for long range soft target interdiction. It is fed by a detachable single stack magazine, which holds 7 rounds. It fires .408 CheyTac or .375 CheyTac ammunition...

.41 10.25 mm 0.410 in .41 Magnum .41 Action Express
.41 Action Express
The .41 Action Express is a pistol cartridge developed in the 1980s to reproduce the performance of the .41 Magnum cartridge in semi-automatic pistols.-History:...

 
.416 10.6 mm 0.416 in .416 Barrett
.416 Barrett
The .416 Barrett or 10.6x83mm centerfire rifle cartridge is a proprietary bottlenecked centrefire rifle cartridge designed in 2005. It is an alternative to the .50 BMG in long-range high-caliber rifles. It was designed in response to a request for a medium/heavy rifle/cartridge combination that was...

, .416 Remington Magnum
.416 Remington Magnum
The .416 Remington Magnum is a .416 caliber of a belted bottle-necked design. The cartridge was intended as a dangerous game hunting cartridge and released to the public in 1989. The cartridge uses the case of the 8 mm Remington Magnum as a parent cartridge. When the cartridge was released in...

, .416 Rigby
.416 Rigby
The .416 Rigby or 10.6x74mm was designed in 1911 by John Rigby & Company of London, England as a dangerous game cartridge and is the first one to use a bullet with a diameter of .416"...

, .416 Weatherby Magnum
.416 Weatherby Magnum
The .416 Weatherby Magnum is a belted, bottlenecked cartridge designed by Ed Weatherby and launched commercially in 1989. It is a dangerous game cartridge intended for the hunting of heavy dangerous game such as elephant and African Cape buffalo. It is considered the most powerful commercial .416...

Long-range sniper rounds If your target is under 500 Yards away and needs less than 1000 Ft. Lbs for an effective kill.
.43 11 mm 0.43 in Sl .43 SL large
.44 10.8 mm 0.427 - 0.430 in .44 Magnum
.44 Magnum
The .44 Remington Magnum, or simply .44 Magnum, is a large-bore cartridge originally designed for revolvers. After introduction, it was quickly adopted for carbines and rifles...

 
.45 11.45 mm
11 mm caliber
This article lists firearm cartridges which have a bullet in the through caliber range.All measurements are in millimeters .-Pistol cartridges:-Revolver cartridges:-Rifle cartridges:-See also:...

 
0.451-0.452 in .45 ACP
.45 ACP
The .45 ACP , also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.-Design and history:The U.S...

, 45GAP 
Handgun .45 calibers, .451 autos and .452 in revolvers
.45 11.6 mm 0.458 in .45-70 Government  Most rifle .45 calibers
.454 11.53 mm 0.454 in .454 Casull
.454 Casull
The .454 Casull is a firearm cartridge, developed in 1957 by Dick Casull and Jack Fulmer. It was first announced in November 1959 by Guns & Ammo magazine. The basic design was a lengthened and structurally improved .45 Colt case...

 
Once considered a wildcat cartridge
Wildcat cartridge
A wildcat cartridge, or wildcat, is a custom cartridge for which ammunition and firearms are not mass produced. These cartridges are often created in order to optimize a certain performance characteristic of an existing commercial cartridge.Developing and using wildcat cartridges does not...

, becoming more common
.458, .46 11.6 mm 0.458 in .460 Weatherby, .458 Winchester Magnum
.458 Winchester Magnum
The .458 Winchester Magnum is a belted, straight-taper cased, dangerous game rifle cartridge. It was introduced commercially in 1956 by Winchester and first chambered in the Winchester Model 70 African rifle. It was designed to compete against the .450 Nitro Express and the .470 Nitro Express...

 
.475, .480 12 mm
12 mm caliber
This article lists firearm cartridges which have a bullet in the to caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge.*Bullet refers to the diameter of the bullet....

 
0.475 in .480 Ruger
.480 Ruger
The .480 Ruger is a revolver cartridge, introduced in 2003 by Sturm, Ruger and Hornady. This was the first new cartridge introduced by Ruger, and was at time of introduction the largest diameter production revolver cartridge, at .-Design:...

, .475 Linebaugh
.475 Linebaugh
The .475 Linebaugh is an extremely potent rimmed revolver cartridge developed by John Linebaugh in the late 1980s. The cartridge is based on the .45-70 Government case cut down to 1.5 inches and loaded with bullets weighing from to...

 
.50 12.7 mm 0.50 in .50 AE, .500 S&W, .50 Beowulf
.50 Beowulf
The .50 Beowulf [12.7×42 mm Rb] is a rifle cartridge developed by Alexander Arms for use in a modified AR-15 rifle. The cartridge utilizes a rebated rim, sized to match the rim of the 7.62×39mm and 6.5 mm Grendel rounds...

, .50 GI
.50 GI
- External links :* *...

 
Desert Eagle
Desert Eagle
The Desert Eagle is a large-framed gas-operated semi-automatic pistol designed by Magnum Research in the U.S. and by IMI in Israel; the pistol is manufactured primarily in Israel by IMI...

, S&W X-Frame, Alexander Arms .50 Beowulf, Guncrafter Industries 1911 .50
.50 12.95 mm 0.510 in .50 BMG
.50 BMG
The .50 Browning Machine Gun or 12.7×99mm NATO is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s. Entering service officially in 1921, the round is based on a greatly scaled-up .30-06 cartridge...

, 12.7 x 108 mm 
M2 Browning machine gun and other heavy machine guns, long range rifles typified by Barrett Firearms Manufacturing products
.57 14.5 mm 0.586 in, 14.88 mm 14.5 x 114 mm
14.5 x 114 mm
The 14.5×114 mm is a heavy machine gun and anti-materiel rifle cartridge used by the Soviet Union, the former Warsaw Pact, modern Russia, and other countries....

, 14.5 mm JDJ
14.5 mm JDJ
The 14.5mm JDJ was created by SSK Industries of Wintersville, Ohio.-Overview:It uses the .50 BMG case with the neck opened up to accept a bullet. It fires the bullet at with the fire-formed load. The Barnes bullet can also be loaded to . It has a destructive device exemption. Only rifles...

 
The 14.5 JDJ cartridge uses a .50 BMG
.50 BMG
The .50 Browning Machine Gun or 12.7×99mm NATO is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s. Entering service officially in 1921, the round is based on a greatly scaled-up .30-06 cartridge...

 case with opened neck, so only rifles chambered for the .50 BMG can be converted to this caliber
.68 17.272 mm 0.675-0.695 in .68 Caliber Paintball marker
Paintball marker
A paintball marker, also known as a paintball gun, is the main piece of equipment in the sport of paintball. Markers use an expanding gas, such as carbon dioxide or compressed air, to propel paintballs through the barrel. Some paintball players refer to the piece of equipment as a "marker" rather...

s
Typically .68 Caliber, not measured metrically and not generally tracked for variations; i.e. projectile size may vary (Not actually a firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...

)
.79 20 mm  0.787 in 20 x 102 mm, 20x138mmB
20x138mmB
The 20×138mmB cartridge was a type of ammunition used mainly for anti-aircraft and anti-tank weapons during World War II. The designation means the caliber was 20 mm, the length of the cartridge case was 138 mm and B indicates it was a belted case...

 
Anti-material rifle and autocannon caliber,
.95 24.13 mm  0.950 in .950 JDJ
.950 JDJ
The .950 JDJ is a large caliber rifle cartridge developed by J. D. Jones of SSK Industries. Jones is also the noted developer of many other well-known cartridges, such as the Whisper family.-Cartridge:...

 
.950 JDJ is the only known cartridge beyond .79 caliber to be used in a rifle


Firearm calibers outside the range of .17 to .50 (4.5 to 12.7 mm) exist, but are rarely encountered. Wildcat cartridge
Wildcat cartridge
A wildcat cartridge, or wildcat, is a custom cartridge for which ammunition and firearms are not mass produced. These cartridges are often created in order to optimize a certain performance characteristic of an existing commercial cartridge.Developing and using wildcat cartridges does not...

s, for example, can be found in .10, .12, and .14 caliber (2.5, 3.0, & 3.6 mm), typically used for short range varmint hunting, where the high velocity, lightweight bullets provide devastating terminal ballistics
Terminal ballistics
Terminal ballistics, a sub-field of ballistics, is the study of the behavior of a projectile when it hits its target. It is often referred to as stopping power when dealing with human or other living targets. Terminal ballistics is relevant both for small caliber projectiles as well as for large...

 with little risk of ricochet. Larger calibers, such as .577, .585, .600, .700, and .729 (14.7, 14.9, 15.2, 17.8, & 18.5 mm) are generally found in proprietary cartridges chambered in express rifle
Express rifle
The term express was first applied to hunting rifles and ammunition beginning in the middle 19th century, to indicate a rifle or ammunition capable of higher than typical velocities. The early express cartridges used a heavy charge of black powder to propel a lightweight, often hollow point...

s or similar guns intended for use on dangerous game.

Shotguns

Shotguns are classed according to gauge
Gauge (bore diameter)
The gauge of a firearm is a unit of measurement used to express the diameter of the barrel. Gauge is determined from the weight of a solid sphere of lead that will fit the bore of the firearm, and is expressed as the multiplicative inverse of the sphere's weight as a fraction of a pound . Thus...

, a related expression. The gauge of a shotgun refers to how many lead spheres the diameter of the bore would equal a pound. In the case of a 12-gauge shotgun, it would take twelve spheres the size of the shotgun's bore to equal a pound. A numerically larger gauge indicates a smaller barrel: a 20-gauge shotgun requires more spheres to equal a pound; therefore, its barrel is smaller than the 12 gauge. This metric is used in Russia as "caliber number": e.g., "shotgun of the twelve caliber." The sixteenth caliber is known as "lordly" . While shotgun bores can be expressed in calibers (the .410 bore shotgun is in fact a caliber measure of .41 caliber [11 mm]), the nature of shotshells is such that the barrel diameter often varies significantly down the length of the shotgun barrel, with various levels of choke and backboring.

Caliber as measurement of length

The length of artillery barrels has often been described in terms of multiples of the bore diameter e.g. a 4-inch gun of 50 calibers would have a barrel 50 x 4 inches = 200 inches long.

Pounds as a measure of cannon bore

Smoothbore cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...

 and carronade
Carronade
The carronade was a short smoothbore, cast iron cannon, developed for the Royal Navy by the Carron Company, an ironworks in Falkirk, Scotland, UK. It was used from the 1770s to the 1850s. Its main function was to serve as a powerful, short-range anti-ship and anti-crew weapon...

 bores are designated by the weight in Imperial pounds of round solid iron shot of diameter to fit the bore. Standard sizes are 6, 12, 18, 24, 32 and 42 pounds, with some 68 pound weapons, and other nonstandard weapons using the same scheme. See Carronade#Ordnance.

From about the middle of the 17th century until the middle of the 19th century, measurement of the bore of large gunpowder weapons was usually expressed as the weight of its iron shot in pounds
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

. Iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 shot
Round shot
Round shot is a solid projectile without explosive charge, fired from a cannon. As the name implies, round shot is spherical; its diameter is slightly less than the bore of the gun it is fired from.Round shot was made in early times from dressed stone, but by the 17th century, from iron...

 was used as the standard reference because iron was the most common material used for artillery ammunition during that period and solid spherical shot the most common form encountered. Artillery was classified thereby into standard categories, with 3 pounders (pdr.), 4 pdr., 6 pdr., 8 pdr., 9 pdr, 12 pdr, 18 pdr., 24 pdr. and 32 pdr. being the most common sizes encountered; although larger, smaller and intermediate sizes existed.

However, in practice there was significant variation in the actual mass of the projectile for a given nominal shot weight. The country of manufacture is a significant consideration when determining bore diameters. For example, the French livre, until 1812, had a mass of 489.5 g whilst the contemporary English (Avoirdupois
Avoirdupois
The avoirdupois system is a system of weights based on a pound of 16 ounces. It is the everyday system of weight used in the United States and is still widely used to varying degrees by many people in Canada, the United Kingdom, and some other former British colonies despite the official adoption...

) pound massed approximately 454 g. Thus, a French 32 pdr. at the Battle of Trafalgar
Battle of Trafalgar
The Battle of Trafalgar was a sea battle fought between the British Royal Navy and the combined fleets of the French Navy and Spanish Navy, during the War of the Third Coalition of the Napoleonic Wars ....

 threw a shot with 1.138 kg more mass than an English 32 pdr.

Complicating matters further, muzzle loaded weapons require a significant gap between the sides of the tube bore and the surface of the shot. This is necessary so that the projectile may be inserted from the mouth to the base of the tube and seated securely adjacent the propellant charge with relative ease. The gap, called windage
Windage
Windage is a force created on an object by friction when there is relative movement between air and the object.There are two causes of windage:# the object is moving and being slowed by resistance from the air...

, increases the size of the bore with respect to the diameter of the shot somewhere between 10% and 20% depending upon the year the tube was cast and the foundry
Foundry
A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal in a mold, and removing the mold material or casting after the metal has solidified as it cools. The most common metals processed are aluminum and cast iron...

 responsible.
English gun classes c. 1800
gun class (pdr.) shot diameter (cm) shot volume (cm3) approx. service bore (cm) mass of projectile (kg)
2 6.04 172.76 6.64 0.90846
3 6.91 172.76 7.60 1.36028
4 7.60 230.30 8.37 1.81339
6 8.71 345.39 9.58 2.71957
9 10.00 518.28 11.00 4.08091
12 10.97 691.22 12.07 5.44269
18 12.56 1036.96 13.81 8.16499
24 13.82 1382.65 15.20 10.88696
32 15.21 1843.50 16.73 14.51572
64 19.17 3686.90 21.08 29.03063


The relationship between bore diameter and projectile weight was severed following the widespread adoption of rifled weapons during the latter part of the 19th century. While guns continued to be classed by the weight of their projectile into the middle of the 20th century, particularly in British service, this value no longer had any relation to the bore diameter as the projectiles themselves were no longer simple spheres and in any case were now more often hollow shells with explosive fillings rather than solid iron shot.

See also

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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