Why can't I get a consistant C.O.L.?

Discussion in 'Reloading' started by KQguy, Mar 15, 2008.

  1. KQguy

    KQguy Well-Known Member

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    I just started shooting a 240gr sierra MK out of my 300 win. mag.When I seat the bullet I cannot get a consistant C.O.L.,it varies + or - .005".I am using a Redding competition seater die,so I know my die is not the problem.All of my cases are trimmed to the same size.The wierd thing is,I can load my 110gr v-max's into the same cases and get consistant C.O.L.'s all day long,it's just the MK's that are giving me fits.I have to seat them all long ,and them seat each one with a different setting on my die to get my desired length,what a pain!Any suggestions?
     
  2. boomtube

    boomtube Well-Known Member

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    Just measure a few bullets OAL. I think you will find the main reason your cartridge OAL varies.
     

  3. BountyHunter

    BountyHunter Writers Guild

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    Measure base to ogive and with most of the SMKs you can see the .005 variance right there. That will give you the variance in COL.

    Bullet OAL will always vary on most bullets, but the seating die stem goes off the ogive or close to it so that is the reason to measure and sort by base to ogive.

    Are you getting a variance in "feel" when seating? if so might have variable neck tension that can inhibit full seating.

    BH
     
  4. royinidaho

    royinidaho Writers Guild

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    BH beat me to it.
     
  5. KQguy

    KQguy Well-Known Member

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    Come to think of it,some do have a different feel.For now,am I doing the right thing by adjusting each one individually to get the same C.O.L.?
    Another problem is,some rounds are harder to chamber than others,even though they all have the same C.O.L.,I think some are hitting the lands,and some are not.What should I do?
     
  6. glassman

    glassman Active Member

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    If you think the bullet is hitting the lands, then there should be a mark on the bullet to show this.

    You say you are checking the COL, what you should be checking is the Ojive of the bullet to the base of the case.
    By checking it this way, you will know how far from the lands that the bullet is seated.

    Nothing will be very accurate, if you go from the tip of bullet and measure (which is COL)

    If the rounds are hard to chamber it can be three things:
    The bullets are seated "off center" to the casing and bumping into the barrel.
    The bullets are seated "out" to far.
    Casing not "sized down" far enough.

    I had a 06 one time that 8 shells out of 20 that I loaded, would not fit into the chamber. Reason was, the bullets were "out of alignment" in the case by 8 thousands. So being I had them seated to .020 off the lands, they were hitting the side of the barrel and not allowing the round to chamber. So this is something you may want to look into.

    Hope this helps.
     
    Last edited: Mar 15, 2008
  7. goodgrouper

    goodgrouper Well-Known Member

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    Sounds to me like you might have inconsistent neck tension and/or the big bullet is crunching powder and impeding the seating process. This sounds very likely as the 110 vmax are seating fine because they are so much shorter.
     
    Last edited: Mar 16, 2008
  8. KQguy

    KQguy Well-Known Member

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    I know I am not having a problem with the bullet crunching the powder,because I can here the powder move around when I shake a loaded round.I think I will look into the inconsistant neck tension though.
     
  9. goodgrouper

    goodgrouper Well-Known Member

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    Shaking the case isn't the best way to check this because kernels can shake loose past the boat tail yet the center of the powder column could still be smashed. A better way to check is just to listen and feel what is going on while you seat the bullet. How much powder are you using and what is your desired OAL?
     
  10. goodgrouper

    goodgrouper Well-Known Member

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    Interesting. .008" out of round is not all that uncommon on badly loaded ammo and I've never seen it cause a problem of not going in the chamber. It sounds like other things were mixing in. Was your ammo measured at the tip of the bullet or somewhere on the brass?
     
  11. glassman

    glassman Active Member

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    I never measured from the tip, only the ojive.
    When I straighten up the rounds that were .008 out, they all slid into the chamber without a problem.

    Try this some time, take a case and bend the neck until it is out of alignment 8 thous and then seat the bullet. But have the bullet just with in .010 off the lands, then see if the case will go in.
    The 06 casings will get the "banana curve" from time to time and the necks start to get a large run-out. This is why I check them regularly on the concentric gage.
    I have only had this problem with the '06, but I guess it could happen on other caliber too.

    Oh..it's not the die that's causing the run-out on the neck either, have tried 2 different brands, same thing. It's probably in the Neck area that's not right.
     
    Last edited: Mar 16, 2008
  12. KQguy

    KQguy Well-Known Member

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    I am using RL 22 @ 63.8 gr.,and a C.O.L of 3.483".
     
  13. goodgrouper

    goodgrouper Well-Known Member

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    I meant where did you run the concentricity dial on the loaded round? On the ogive, neck, or tip?
    I can find factory ammo that is running .008" on the tip or ogive and it will go in the chamber fine.

    I assume you are straightening the loaded round with a Bersin tool?

    I still can't figure out why you have this bad of runout. If your chamber has bad alignent, your fired brass would show the bad concentricity. If your fired brass is good but your sized brass is bad, then the problem is in your dies. Something ain't right wherever it is and it isn't normal for a 30-06.
     
  14. goodgrouper

    goodgrouper Well-Known Member

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    Sounds like a normal load. Try seating a bullet into a sized, non-primed, non-powdered case and see if the problem persists.