Whats a 7.62 ?

[ciphery]

The R is important and doesn't mean "Russian".

Otherwise 7.62x51R would be a Russian calibre when really it's the metric designation for .30-30 Winchester.

Most European calibres are simply known by their metric dimensions.

Ex.
7.62x39mm
5.45x39mm
6.5x55mm
8x57mm
9.3x57mm
9.3x62mm
7.5x55mm

There are other names, usually country or manufacturer who created it, but they aren't used as often as with modern American cartridges.

It's kind of like old blackpowder American cartridges like .32-20, .44-40, .45-70, .50-90, etc. You can add the company name but it usually isn't required; everyone knows what you mean.
With modern American cartridges the name really is important. You can say you're shooting a ".300 magnum" but is that a Winchester or Weatherby?

Guess you've never seen the differences between 40-60win, 40-60 marlin, or a 40-60 maynard

 

[Kevin M.]

There are a lot of different 7.62 calibre firearms and calibres on the market.

Here are three of the most common at the moment...

7.62x39 - SKS, AK-47, AR-15 variants, RPD etc.

7.62x51 - M-14, FN-FAL, Remington 700 (among dozens of other calibres, but 7.62x51, or .308 winchester, is one of the most common.) etc...

7.62x54R - Mosin Nagant, SVT-40, Goryunov, PKM, etc.


The Russian 7.62x54 Rimmed cartridge is roughly comparable to the other main battle rifle calibres of its time, namely 30-06, 8mm, and 7.7Jap.

 

[nullshine]

Metric designation. Some calibers have both a metric based and imperial based designation, some only have the metric. 308 winchester for example is also known as 7.62x51. The 7.62 refers to the diameter of the projectile while the 51 refers to over all length of the Case.

Like mentioned, 7.62x54r is Russian. 7.62mm bullet, 54mm oal and the "r" indicates it's a rimmed cartridge.

7.62mm / (25.4 mm per inch) = .30

So is 7.62mm not the bore diameter? .308 being the projectile diameter. (In the case of 7.62x51).

Similiar situation for .303 British.

 

[sail32]

http://62x54r.net/MosinID/MosinAmmo.htm