Concentricity

Discussion in 'General Discussion' started by StrayDog, Sep 27, 2004.

  1. StrayDog

    StrayDog Member

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    I just started using a concentricity guage. My full length resized brass has excessive runout of between .007" and .012".
    The only good news is the fired rounds are about .002" and some less.

    Have any ideas how to straighten this out?
     
  2. Dave King

    Dave King Well-Known Member

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    What were your hand load group sizes before you checked the concentricity?? If they were small proceed to step A, if large proceed to step B.

    A. Stop using the concentricity guage.

    B. Stop using the dies you have (or do a very careful setup and die check). Buy some competition dies or Wilson neck size and seater type dies. Proceed to step C.

    C. Stop using the Concentricity guage. [​IMG] [​IMG]
     

  3. StrayDog

    StrayDog Member

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    As crowded as the ranges are becoming, that's probably the best advice. The groups are probably good enough for most hunting situations, and I can fine tune in the spring.
    The 6.5-06 groups between 1 1/2" to 2" @ 200 yards.
    And the .270 groups about 3" @ 200 yards.
     
  4. Dave King

    Dave King Well-Known Member

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    FWIW I have a concentricity guage too but nowadays it only clutters up a reloading gear drawer... looks neat in there but it's now a "leaverite" device.
     
  5. Guest

    Guest Guest

    Dave,
    I like your advice! "If it works, don't fix it!" Good Shootin'
     
  6. brian b

    brian b Well-Known Member

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    Aug 15, 2004
    Straydog,
    If you use a bushing die like a redding S
    die it will be a problem no more. most
    runout is caused by oversizing your brass,
    by using the correct size bushing you only
    size as much as needed and wahla your concentricity guage flatlines.
    B
    p.s. then use a "BR" or inline seater
    (a BR or inline seater wont make it any
    better just keep it from getting worse like
    a standard seater will)

    [ 09-28-2004: Message edited by: brian b ]
     
  7. jb1000br

    jb1000br Well-Known Member

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    stray--sinclair sells blanks with only a caliber size hole in it--all you have to do is run your own reamer in [​IMG]

    JB

    [ 09-29-2004: Message edited by: jb1000br ]
     
  8. StrayDog

    StrayDog Member

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    Thats good to know.
    I can send a blank to the same gunsmith that rebarreled, and he could use the reamer he cut the chamber with. [​IMG]
    I'm thinking about getting one of those generic caliber decapping dies that decap without sizing,
    Then I could full length size without the decapping rod or expander ball in the die.
    Then neck size and seat with in-line hand tools.
    That's a lot of steps but not trying to have so many things locked into alignment to accomplish one step for everything might give me th eguage flat line. Might shrink the groups too. [​IMG]
     
  9. COBrad

    COBrad Well-Known Member

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    Great topic. I got a concentricity guage this summer for the first time. I was unpleasantly surprised at the amount of runout I was getting in some calibers, although the rifles shoot well. My Cooper 22-250 pretty consistently shoots in the mid .3's, and runout of rounds loaded in Redding competetion dies runs only .001 - .002. A tech at Sinclair offered his opinion that runout gets way too much credit for both good or bad accuracy in all but bench rifles. So, I did a little testing with a Kimber .243 firing segregated rounds with from .001 to .006 runout. I found no difference in accuracy in this instance. Seating depth and powder charge weight have thus far proved to have far more effect in this rifle.
     
  10. StrayDog

    StrayDog Member

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    yep, a flat line on the guage is what I'd like to see. That way I would know my groups size was being controlled by other things.
    Where do people buy the in line seaters in various calibers? I see them at Midway in 300 win mag for example but not in 6.5-06?
    I know the benchrest competitors use some really far out calibers, they must be getting them somewhere?

    [ 09-29-2004: Message edited by: StrayDog ]
     
  11. james_ogburn

    james_ogburn Active Member

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    Dec 16, 2003
    Straydog, I don't use a concentricity gauge, but I did take the expander ball out of my dies. I deprime my .308 brass using a .300 WM die, and took the expander assembly out of the .308 die. The targets told me that it helped enough to make a difference.