Found something about .308 and 7.62mm.

Discussion in 'The Ammo & Reloading Forum' started by Mosin_Nagant_Fan, Nov 10, 2010.

  1. Mosin_Nagant_Fan

    Mosin_Nagant_Fan Active Member

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    About a year ago I asked about ammo and how people get 7.62mm into .308in when .308in = 7.82mm (rounded the the nearest hundredth), only to get pretty much told off and no strait answer. After some research and calculating (both on the computer and by hand) I found that the ammo (bullet) IS .308in (7.82mm) in diameter but the bore on the gun is 7.62mm, at the lands (found out where the 7.62mm bit in the last sentence from Wikipedia).
  2. Bindernut

    Bindernut Well-Known Member

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    Yup,
    That's a typical difference in how the European and British cartridges are spec'd to the land diameter instead of the groove (or bullet) diameter out compared to the US method of bore size naming.

    Similar examples...
    The .303 British, which uses .311/.312" bullets
    The 7x57 Mauser (called .275 Rigby in the UK) which uses .284" (7.21mm) bullets
    The 8x57 Mauser uses .323" or 8.21mm bullets.
  3. LDBennett

    LDBennett Well-Known Member

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    Cartridge names are virtually meaningless. Often the bore or grove diameter doesn't match anything in the name. Some names have historical connections like the black powder cartridges where the diameter and the amount of black powder is part of the name. Sometimes the name is made up as a sales gimmick.

    So take no information from the name as to the size of the bullet or the grooves or the the bore or anything else. Refer to a good reloading manual for the actual dimension.

    LDBennett
  4. JLA

    JLA Well-Known Member

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    yup, thats whay a .300 win mag uses the same .308 caliber projectile as the .308 norma magnum, one cartridge is names for the groove diameter and one for the bore diameter
  5. LDBennett

    LDBennett Well-Known Member

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    And some for neither groove or bore diameter!
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