Help needed on measurement techniques

Discussion in 'Reloading' started by bookworm, May 23, 2010.

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  1. bookworm

    bookworm Well-Known Member

    Dec 4, 2008
    I have a Sinclair concentricity gauge and want to make sure I'm measuring things correctly.

    1. For bullet runout, where on the bullet to you measure? I've read that you want to measure on the Ogive, but the Ogive isn't one single point but a curved section - right? I imagine the main point is consistency between measurements, but would like to know if there is a conventional location on the bullet I should use for reference on answer 2 below.

    2. What is a reasonably good bullet runout number when a reloading process is working well?

    3. For case neck concentricity/runout, where on the neck do you measure? Out at the edge? Middle?

    4. What is a reasonably good neck runout number that would signify a good usable case?

    I know I've probably over simplified things, so appreciate any thoughts and advice. I'm trying to tighten up groups on a LRH rig and not shooting bench rest...I know the answers to 2 & 4 above might be different if I were talking BR.
  2. MagnumManiac

    MagnumManiac Well-Known Member

    Feb 25, 2008
    I no longer do this, too many headaches!

    I used to measure bullet run out adjacent to the tip on HP's and behind the tip on SP's/BT's.

    I used to measure neck run out in the forward third of the neck before seating bullets, and the same spot after seating bullets.
    You must be sure that you're measuring above/on the bullet shank, behind it will give you erroneous readings if it's a long neck and a short bullet.
    Both readings should be no more than .002", .001" was my limit for long range work, but most of my cases would show less than 3 tenths run out on my target rifles.
    Some of my hunting rifles would show more than .005" of bullet run out and still shot very well.
    I never actually checked neck run out or neck thickness on my hunting rifles, because I never intended to neck turn them anyway.