Why do SAAMI cartridge drawings contain TWO drawings?

Discussion in 'Handloading and Reloading' started by JimGnitecki, Apr 14, 2021.

  1. JimGnitecki

    JimGnitecki Member

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    Why do SAAMI cartridge drawings contain TWO drawings? Here is an example (the 6.5 Creedmoor SAAMI cartridge drawing set):

    SAAMI 6.5 Creedmore Cartridge Dimensions - 1.jpeg

    The one difference obvious to me is that the bullet is not shown in the second drawing. But there are other differences that I do not understand.

    For example:
    In the top drawing, the base to top of neck dimension is 1.920" -.020"
    In the bottom drawing that "apparently" same measurement is shown as 1.925", which would appear to contradict the 1.920" -.020" in the top drawing.

    Can someone who understands the SAAMI drawing specs provide some clarifications?

    Jim G
     
    Last edited: Apr 14, 2021
  2. Sefuller5741

    Sefuller5741 Member

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    I think the second drawing might be the chamber?
     
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  3. Blue68f100

    Blue68f100 Member

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    The second is the chamber spec.
     
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  4. JimGnitecki

    JimGnitecki Member

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    Ah, thank-you both! That makes sense.

    Jim G
     
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  5. DocRock

    DocRock Member

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    ^^^^^^

    One for cartridge; one for chamber.
     
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  6. Mark_Mark

    Mark_Mark Member

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    one for earth and one for mars! yes, different atmosphere pressures
     
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  7. JimGnitecki

    JimGnitecki Member

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    Yes, what stopped me from even thinking about the 2nd drawing being for the CHAMBER is that SAAMI calls the whole drawing set a "CARTRIDGE" specification! :)

    Jim G
     
  8. edwardware

    edwardware Member

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    They don't. The second drawing is a chamber, not a cartridge.
     
  9. higgite

    higgite Member

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    Note on the lower right side of drawing where it says "CHAMBER". That's a clue. ;)
     
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  10. alfsauve

    alfsauve Member

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    For cartridge dimensions they give the max size with a negative tolerance. And for the chamber the minimum size with the positive tolerance.
     
  11. shoobe01

    shoobe01 Member

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    And even right above where it says the 6.5 Creedmore "Maximum Cartridge / Minimum Chamber" as a title for the whole thing. Slash: both.

    It's all in there, you just need to know how to read dense engineering drawings.
     
  12. NMexJim

    NMexJim Member

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    It's labeled right on the drawing - Cartridge upper drawing and Chamber lower drawing.
     
  13. JimGnitecki

    JimGnitecki Member

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    That makes sense! That ensures that a cartridge made to maximum spec will always fit inside a minimum spec chamber. Makes the specs and tolerances understandable.

    Jim G
     
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