7.62 mm caliber is a nominal caliber

Caliber

In guns including firearms, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it....

 used for a number of different cartridges. Historically, this class of cartridge was commonly known as .30 caliber, the Imperial unit

Imperial unit

The system of imperial units or the imperial system is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced. The system came into official use across the British Empire...

 equivalent, and was most commonly used for indicating a class of full power military main battle rifle (MBR) cartridges. The measurement equals 0.30 inches or 3 decimal line

Line (length)

The line is a unit of measurement, one line being equal to of an English inch. It was defined as one-quarter of a barleycorn, which defined the inch even before 1066. The French ligne was simarly defined as of the pouce...

s, written .3″ and read as Three-Line.

7.62 mm refers to the internal diameter of the barrel at the lands (the raised helical ridges in rifled gun barrels). The actual bullet caliber is normally .308 in (7.82 mm), although Soviet weapons commonly use a .311 in (7.91 mm) bullet, as do older British (.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...

) and Japanese cartridges.

Pistol cartridges in 7.62 mm caliber

There are many pistol cartridges in this caliber, but most common are:

• 7.62×25mm Tokarev, also known as 7.62 mm TT, used in the Tokarev
  Tokarev
  Tokarev , or Tokareva , may refer to:* Anton Tokarev , a Russian pair skater* Boris Tokarev , a Russian athlete* Boris Tokarev , a Russian actor...
  
   pistol, and many of the WWII Soviet submachine guns.
• 7.63×25mm Mauser
  7.63×25mm Mauser
  The 7.63×25mm Mauser round was the original ammunition of the Mauser C96 service pistol. This cartridge headspaces on the shoulder of the case. The basis of this cartridge was the 7.65×25mm Borchardt cartridge of 1893, the only successful automatic pistol cartridge in production at the time...
  
  , which was the basis for, and has nearly identical dimensions to the Tokarev, but has different loading specifications
• 7.65×22mm Parabellum
  7.65×21mm Parabellum
  The 7.65×21mm Parabellum is a pistol cartridge that was introduced in 1898 by German arms manufacturer Deutsche Waffen und Munitions Fabriken for their new Pistol Parabellum...
  
  
• 7.65×17mm Browning
  .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...
  
   also known as the .32 ACP.

Revolver cartridges in 7.62 mm caliber

Some of the revolver cartridges in this caliber are:

• 7.62×38mmR used only in the Nagant M1895
  Nagant M1895
  The Nagant M1895 Revolver is a seven-shot, gas-seal revolver designed and produced by Belgian industrialist Léon Nagant for the Russian Empire. The Nagant M1895 was chambered for a proprietary cartridge, 7.62x38R, and featured an unusual "gas-seal" system in which the cylinder moved forward when...
  
   revolver
  Revolver
  A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing. The first revolver ever made was built by Elisha Collier in 1818. The percussion cap revolver was invented by Samuel Colt in 1836. This weapon became known as the Colt Paterson...
  
  
• .32 Long Colt
  .32 Long Colt
  The .32 Long Colt is an American centerfire fire revolver cartridge.Introduced by Colt's with the New Line revolver in 1875, the .32 Colt was inspired by the .320 Revolver...
  
   Originally chambered in small frame Colt revolvers and the Marlin model 1892 rifle, this cartridge used a heeled bullet with a case the same diameter as the major diameter of the bullet. It shared dimensions with the .32 rimfire cartridge of the same length. Not to be confused with the .32 Colt's New Police cartridge.
• .32 S&W Long
  .32 S&W Long
  The .32 S&W Long is a straight-walled, centerfire, rimmed handgun cartridge, based on the earlier .32 S&W cartridge. It was introduced in 1896 for Smith & Wesson's first-model Hand Ejector revolver...
  
   Also known as the .32 "Colt's New Police" When chambered in Colt revolvers. The original loading for this cartridge used a round nose, or flattened round nose (in the case of the .32 Colt's N.P.) and was chambered widely in revolvers made in the US and Europe through WWII. This cartridge is used in several modern target pistols (not revolvers) with flush seated wadcutters. The short version of this cartridge (.32 S&W) was chambered in many break-top revolvers at the end of the 19th and beginning of the 20th centuries in the US and Europe.
• .32 H&R Magnum
  .32 H&R Magnum
  The .32 H&R Magnum is a rimmed cartridge designed for use in revolvers. It was developed in 1984 as a joint venture between Harrington & Richardson and Federal Cartridge...
  
   Is the only revolver cartridge in this caliber which is in wider use today, mostly in small-frame revolvers. This is an extended version of the much earlier .32 S&W long, which is an extended version of the .32 S&W.
• .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...
  
   Is a new cartridge developed jointly by Ruger and Federal. This cartridge is an extended version of the .32 H&R Magnum.

Rifle cartridges in 7.62 mm caliber

The most common & historical rifle cartridges in this caliber are:

• Soviet 7.62x39mm, also known as the 7.62 mm Soviet, M43, or occasionally .30 Short Combloc, designed for the SKS
  SKS
  The SKS is a Soviet semi-automatic rifle chambered for the 7.62x39mm round, designed in 1943 by Sergei Gavrilovich Simonov. SKS-45 is an acronym for Samozaryadnyj Karabin sistemy Simonova, 1945 Simonov system, 1945), or SKS 45. The Sks is a scaled down version of the PTRS-41 anti-tank rifle also...
  
   and used in the AK-47
  AK-47
  The AK-47 is a selective-fire, gas-operated 7.62×39mm assault rifle, first developed in the Soviet Union by Mikhail Kalashnikov. It is officially known as Avtomat Kalashnikova . It is also known as a Kalashnikov, an "AK", or in Russian slang, Kalash.Design work on the AK-47 began in the last year...
  
   and AKM
  AKM
  The AKM is a 7.62mm assault rifle designed by Mikhail Kalashnikov. It is an upgraded version of the AK-47 rifle and was developed in the 1950s....
  
   assault rifle
  Assault rifle
  An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...
  
  s and RPK
  RPK
  The RPK is a 7.62x39mm light machine gun of Soviet design, developed by Mikhail Kalashnikov in the late 1950s, parallel with the AKM assault/battle rifle...
  
   and RPD
  RPD
  The RPD is a 7.62mm light machine gun developed in the Soviet Union by Vasily Degtyaryov for the intermediate 7.62x39mm M43 cartridge. It was created as a replacement for the DP machine gun chambered for the 7.62x54mmR Mosin rifle round...
  
   light machine guns.
• 7.62x51mm NATO, and its civilian variant .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...
  
  , sometimes incorrectly described as .308 NATO by persons mixing English measurements used by some civilians with metric measurements used by the NATO organization.
• 7.62×54mmR another Russian cartridge that was first used in the Mosin-Nagant
  Mosin-Nagant
  The Mosin–Nagant is a bolt-action, internal magazine-fed, military rifle invented under the government commission by Russian and Belgian inventors, and used by the armed forces of the Russian Empire, the Soviet Union and various other nations....
  
   rifle since 1891. The modern versions of the cartridges to this day are in wide use in numerous world armies as sniper rifles (particularly the SVD family) and machine guns (numerous types, many developed from AK family such as the PKM
  PK machine gun
  The PK is a 7.62 mm general-purpose machine gun designed in the Soviet Union and currently in production in Russia. The PK machine gun was introduced in the 1960s and replaced the SGM and RPD machine guns in Soviet service...
  
  ).
• .30-06 Springfield
  .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...
  
   US Military cartridge for both World Wars and Korea, known as the 7.62x63mm in metric measurement.
• .30 Carbine
  .30 Carbine
  The .30 Carbine is the cartridge used in the M1 Carbine introduced in the 1940s. It is an intermediate round designed to be fired from the M1 carbine's 18-inch barrel.-History:...
  
  , used in the M1/M2/M3 Carbines
  M1 Carbine
  The M1 carbine is a lightweight, easy to use semi-automatic carbine that became a standard firearm for the U.S. military during World War II, the Korean War and the Vietnam War, and was produced in several variants. It was widely used by U.S...
  
  , sometimes called the 7.62x33mm.
• .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...
  
  , used in Lee-Metford
  Lee-Metford
  The Lee-Metford rifle was a bolt action British army service rifle, combining James Paris Lee's rear-locking bolt system and ten-round magazine with a seven groove rifled barrel designed by William Ellis Metford...
  
   and Lee-Enfield
  Lee-Enfield
  The Lee-Enfield bolt-action, magazine-fed, repeating rifle was the main firearm used by the military forces of the British Empire and Commonwealth during the first half of the 20th century...
  
   rifles.
• .308 Norma Magnum
  .308 Norma Magnum
  The .308 Norma Magnum cartridge was created by Nils Kvale at Norma, Sweden. Like the larger .358 Norma Magnum it is based on the .300 H&H Magnum. The length of the case is the longest that would fit in a standard Mauser action. While it appeared to have a bright future initially, it was soon...
  
  
• .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...
  
   used by many hunting/sniper rifles, sometimes called the 7.62x67mm.
• .30-378 Weatherby Magnum
  .30-378 Weatherby Magnum
  The .30-378 Weatherby Magnum is a cartridge introduced by Weatherby in 1996 that uses the same case as the previously existing .378 Weatherby Magnum and .460 Weatherby Magnum, necked down to a 30 caliber bullet. It is offered with bullets between 165 and 200 grains in factory loading, generating...
  
  
• .30-30 Winchester
  .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...
  
   A popular Deer hunting cartridge typically used in Lever-Action Rifles such as the Winchester Model 1894
  Winchester Model 1894
  Winchester Model 1894 is a lever-action rifle which became one of the most famous and popular hunting rifles...
  
   and Marlin Model 336
  Marlin Model 336
  The Marlin Model 336 is a lever-action carbine made by Marlin Firearms. It is most often chambered in .30-30 Winchester or .35 Remington, though it has also been chambered in several other cartridges over the years.-History:...
  
  also adapted to European sporting guns as 7.62x51Rmm.
• .30 R Blaser, used in break-action rifles for hunting medium to large game.
• 30TC.