Adjusting seating depth?

Discussion in 'Reloading' started by devildoc, Mar 2, 2006.

  1. devildoc

    devildoc Well-Known Member

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    In the past I've always just used a stoney point bullet comparator to discern max seating depth and seat a little bit back from that (unless that is too long for the magazine). However after reading this forum I'd like to try playing with my seating depth a little. So my question is, what procedure do some of you pros use to adjust your seating depth? What increments do you test etc.
     
  2. Ol'Gator

    Ol'Gator Well-Known Member

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    I know you've ask for pros opinion but I'm gonna put in my $.02 anyway. I've been using the same stoney point tools to determine the oal that just touches the lands. Once I feel like I have the best powder load and only then do I start backing away from the lands. I move in 4 thousandths increments but couldn't tell you why I chose this amount. I like to start off touching or very near so I only have one way to travel for my testing. Sometimes (with some guns) seating depth isn't as critical as you might imagine. I know some find the sweet spot moving into the lands. That's what makes this all so interesting.
     

  3. BountyHunter

    BountyHunter Writers Guild

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    IF mag concerns drive your OAL. Start at mag max OAL and come off .010 increments and see what the groups do.

    You should hit a point where they tighten then loosen up. In that area you might reshoot at .005 increments if they are not tight enough for you.

    Generally most mags throats move about .003-.005 or more with every 100 rds fired, so to maintain same ogive-lands relationship, your seating depth has to move forward the amount of the throat erosion.

    The sinclair intl tool, Sinclair Seating Depth Tool, #09-400 cost is $28.95 is the easiest to use for measuring throat erosion and location of the lands. www.sinclairintl.com

    BH
     
  4. devildoc

    devildoc Well-Known Member

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    I'm sorry, I missed what you were saying at the end there Bounty, Are you saying the magazine's or the barrel's throat will erode every 100rounds. I'm assuming you mis-typed, because I was unaware a magazine had a throat.
     
  5. relabbe

    relabbe Active Member

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    I guessed Bountyhunter is referring to Magnum rifles, not magazine.
     
  6. Eaglet

    Eaglet Well-Known Member

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    Yes! That's exactly what he's saying.
     
  7. devildoc

    devildoc Well-Known Member

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    Ahhhh, well that makes a little more sense.
     
  8. Ol'Gator

    Ol'Gator Well-Known Member

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    Also keep in mind changing bullets brand, weight, style often times change oal.
     
  9. BountyHunter

    BountyHunter Writers Guild

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    I was referring to magazine max oal and then to magnum calibers moving the throat about .003-.005 or more for magnum cartridges.

    BH