Headspace measurement

Discussion in 'Reloading' started by hc7mm, Jun 1, 2009.

  1. hc7mm

    hc7mm New Member

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    First post.
    I have been reloading used brass for my Remington 700 7mm remington mag untill now. Bought a bag of winchester brass. Every case of the new brass mearsures 0.018 less or shorter than once fired (fired some factory ammo ) brass. This is using the RCBS presicion mic gauge. The once fired brass measures 0.002 under zero on the gauge the new brass measures 0.018 under zero. Is this too much of a head space gap to load and shoot?

    Thanks
     
  2. hc7mm

    hc7mm New Member

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    I find my answer...........lightbulb......i went back and checked the factory case that has not been fired........and it measured the same as the new unprimed brass.
     

  3. boomtube

    boomtube Well-Known Member

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    Most factory brass is sized too short for a snug fit in any standard chamber. Fact of life.
     
  4. woods

    woods Well-Known Member

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    This brings up a quesstion I don't know the answer to: Does the RCBS Precision Mic measure the actual headspace on a belted case or the gap at the shoulder like the Hornady Headspace gauge?
     
  5. boomtube

    boomtube Well-Known Member

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    "Does the RCBS Precision Mic measure the actual headspace on a belted case "

    No, it measures to the shoulder.

    Bui, the only "headspace" that matters to a reloader for any bottle-neck case IS to the shoulder. That's where the various headspace tools measure; Hornady, RCBS or Sinclair.

    NOTE:

    ...AND the newer tool by Innovative Technologies, shown below.
    -------------------------------------------------------------------------------------------------------------------
    Sorry Larry, your's is so new I haven't used, or even seen it, but it looks fine to me. I'd like to have one. But, I have the others so it seems foolish for me to add another. One Florida boy to another, I do think your's is what I'd get if I had to replace all of my case measurment tools tomorrow! Good luck with it. :)
     
    Last edited: Jun 3, 2009
  6. larrywillis

    larrywillis Well-Known Member

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    Boomtube .......

    You're right, all handloads for bottleneck cases should be headspaced on the shoulder. Unlike the RCBS Precision Mic, our Digital Headspace Gauge works on ANY bottleneck cartridge.

    [​IMG]

    Once this gauge is zeroed on a fireformed case, it can measure your handloads. The gauge then displays the chamber clearance that YOUR handloads will have in YOUR particular chamber. No bushings or special tools required. That allows you to set your die height perfectly at - .002" shorter than your fireformed case.

    - Innovative
    Check it out at: WWW.LARRYWILLIS.COM
     
  7. Moman

    Moman Well-Known Member

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    I have a Rem 700 in 300 WM and new brass stretches .014 at the shoulder. It shoots new brass extremely well (1/2"+) but does a bit better with fire forming. I don't think you have too much to worry about when you find the right load, but it should do quite a bit better once you fire form it.
     
  8. larrywillis

    larrywillis Well-Known Member

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    You shouldn't have any problems as long as you accurately setup your sizing die. That requires more information than you'll get from reading the instructions that came with your dies.

    Even fireformed brass needs to have the shoulder bumped back. There's no advantage to neck sizing anymore.

    - Innovative