280 AI trim to length

Discussion in 'Reloading' started by slas, Apr 15, 2018.

  1. slas

    slas Well-Known Member

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    I noticed in my research than many post the trim to length for the 280 AI at 2.525, whereas the Sierra manual post it as 2.515. I then noticed in the manual diagram the case size showed 2.525 also. Then read else where you're supposed to trim .010 below max case length. I guess I never paid much attention to the fact that the trim to size was always .010 less than the size shown in the diagram.

    I guess my question is what are you trimming to? If you're trimming to 2.525 why that as opposed to suggested trim to length?
     
  2. lancetkenyon

    lancetkenyon Well-Known Member

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    .010" below max case length. 2.515" for SAAMI spec chambers.
     
  3. slas

    slas Well-Known Member

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    Just seemed strange when doing a google query that so many show 2.525
    Understand, just seemed strange to see several quoting 2.525 as the trim to length. I guess I never really paid much attention, just went to the book and that was the length I used. I never saw alternative trim to lengths when researching on my other cartridges.
     
  4. philipbrousseau

    philipbrousseau Well-Known Member

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    kind of nice to use a sinclaire chamber length guage and know. only a few $.
     
  5. Edd

    Edd Well-Known Member

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    You need to check the actual length of your chamber. The SAAMI spec for the chamber is 2.560" with a tolerance of +.015". So you could have a chamber that measures 2.575" and be within specs.
     
  6. philipbrousseau

    philipbrousseau Well-Known Member

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    all of the chambers i have measured have had a longer trim length than noted in the reloading manuals. knowing the length saves a lot of trimming. trim to .010 less than chamber length.
     
  7. slas

    slas Well-Known Member

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    I have a lot of reloading goodies but this isn't one of them. I might forgo buying one and try some of the ideas from searching on "homemade chamber length guage". I like the idea of cutting the neck off, deburing, seating the bullet, then chambering with the cut off piece of the neck on the tip of the bullet. Seems easy and accurate.
     

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  8. philipbrousseau

    philipbrousseau Well-Known Member

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    good idea
     
  9. slas

    slas Well-Known Member

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    Finally got around to this, the winning number is 2.565. A bit longer than I expected....I obviously haven't found any of my cartridges even close to this length. Longest I've found is around 2.530 on some once fired I bought. They range from 2.518 to that so I'm thinking for consistency's sake trim all to the lowest common denominator?
     

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    Last edited: May 1, 2018