Case neck thickness?

Discussion in 'Reloading' started by KQguy, Mar 15, 2009.

  1. KQguy

    KQguy Well-Known Member

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    Is there a standard size for case neck thickness?I have two different lot #'s of winchester brass for a 7mmWSM.One batch measures .013"-.014",the other .015"-.016".I neck turned the first batch,and just cleaned them up to .013"(just scraping off the high spots).Before I turn down the other batch to .013",to match the first batch,I just wanted to make sure I am not making a mistake.Normally I only like to just cut about 70% off,but in this case I will most likely be cutting 100%.Is .013" a good size,even though they are currently .015-.016" now?
     
  2. boomtube

    boomtube Well-Known Member

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    "Is there a standard size for case neck thickness?"

    No. There is only a maximum neck diameter of the loaded rounds which is just under the minumum diameter of a standard chamber.
     

  3. nheninge

    nheninge Well-Known Member

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    Just finished turning some win7mm brass. I too found the same variances. I took them all down to 14, but I spend a lot of time/effort sorting by neck variance. this gets rid of the cases with > 2-3 thou neck variance. And there are quite a few with win brass. I routinely order 100 new brass for each 50 cases I keep. BR shooters would even cull more. However, it all depends what neck is in your chamber. Is it a factory neck, a no-turn, or a tight neck? If it is a factory neck, just take enough off to even up the necks as much as possible. Not much benefit beyond that. Your factory barrel will likely hinder your accuracy before your necks.
     
  4. KQguy

    KQguy Well-Known Member

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    This is for a custom rifle,which I have not got back yet.Maybe I could ask my smith and see what he say's.
     
  5. BountyHunter

    BountyHunter Writers Guild

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    If this is for a custom rifle, you had better know your neck diameter from the reamer and chamber before you start turning or you are wasting your time and brass.

    BH
     
  6. Winchester 69

    Winchester 69 Well-Known Member

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    Typically, you want to turn your brass to achieve 0.003" clearance between the neck and chamber. BR shooters like to get closer to 0.002".
     
  7. J E Custom

    J E Custom Well-Known Member

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    As long as the neck dia. of the chamber is .003 or .004 larger .012 to .016 is a good wall .thickness.

    I like .014 as my standard and order the reamers to fit this with .003 clearance with a
    loaded round.

    Thicker is better if the chamber will handle it.(Better grip on the bullet and longer life)

    The main thing is that they are all the same and turned until they clean up with enough
    clearance.

    J E CUSTOM
     
  8. Ackley Man

    Ackley Man Well-Known Member

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    Unless you have a gun that has a custom barrel that was chambered to be a tight neck (less than minimum SAMI spec) you need only to cut the high spots off for all the brass. Don't try to uniform all of the brass from one neck thickness to another. You will merely thin the necks and invite premature neck splits. With a standard chamber you are waisting your time as it will not impact accuracy. You would be better off to buy a bushing neck die with different bushings so you can keep the neck tension the same frrom one neck thickness lot to another. Neck tension will impact accuracy.