necking up

Discussion in 'Reloading' started by tapalmer99, Jul 2, 2008.

  1. tapalmer99

    tapalmer99 New Member

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    Jul 2, 2008
    I have heard the terms "necking-up & necking-down" several times, but don not understand what the purpose is, and am unclear on how to do it.

    Can someone give me a brief explanation on how, and why, it is done?

    Thanks.

    - tapalmer99@aol.com
     
  2. KRP

    KRP Well-Known Member

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    Necking up is enlarging the case neck to accept a larger diameter bullet, necking down is just the opposite. Allows use of different caliber with a certain case. Sometimes it is as easy as a single pass through a die with the smaller/larger neck, sometimes it needs to be done in several steps.

    Some common examples:

    338/300RUM(Edge) is the 300RUM case necked up to 338 caliber.

    6.5-284 is the 284Win case necked down to 6.5(264) caliber.
     

  3. tapalmer99

    tapalmer99 New Member

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    Does the bullet diameter need to stay smaller than the rim diameter? What would the rules be?

    (Thanks for such a quick response!)
     
  4. KRP

    KRP Well-Known Member

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    Yes, for all practical purposes, otherwise the neck would be larger than the base and the cartridge won't chamber.