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Thread: Neck turning difficulty

  1. #1
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    Neck turning difficulty

    I'm having a little trouble when I turn the necks on some Lapua 220 Russian brass which has had the neck expanded up to 6mm. The turning Arbor starts into the neck with a slight amount of interferance, (which is good), but when the Arbor gets in far enough to be at the neck/shoulder junction it requires a lot of force to push it past this point.

    Am I doing something wrong or missing a step?

  2. #2
    Join Date
    Nov 2014
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    Donut would be my guess. Might inside neck ream or I think there is a way to move the extra brass to the outside and turn it off. Hopefully Someone more experienced than me will address this.

  3. #3
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    Will resizing the case and expanding the neck [which he likely already did] move the donut to the outside?

  4. #4
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    634

    Possible information

    A couple of guys Mike Bryant and Dan Lilja have a few notes and pictures on Accurate Shooter @ "Neck Turning with lathe or mill."
    Might contain info you can use.
    Centerfire

  5. #5
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  6. #6
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    more possibilities

    Upon revisiting Accurate Shooter and putting in 'Neck Turning' a lot of information drops down. Number 4 is pretty good regarding the cutting angle of the tool used to get the correct removal of OD brass at the neck shoulder junction to eliminate reaming need.
    Centerfire

  7. #7
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    Quote Originally Posted by antelopedundee View Post
    Oh, man, I could use that kind of donut!

  8. #8
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    Quote Originally Posted by Centerfire View Post
    Upon revisiting Accurate Shooter and putting in 'Neck Turning' a lot of information drops down. Number 4 is pretty good regarding the cutting angle of the tool used to get the correct removal of OD brass at the neck shoulder junction to eliminate reaming need.
    Centerfire
    My problem is getting the turning arbor in far enough to get the cutter into the brass.

  9. #9
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    Mar 2018
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    You need to expand up a thou more or find a mandrel 1 thou smaller. You don' want the brass to tight or everything gets to hot and it starts to change all your dimensions through expansion.
    John

  10. #10
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    Has anyone tried an inside reamer on the 220 Russian case that has had the neck expanded? If I were to do this I would have to get a case holder for the 220 Russian case, i think.

  11. #11
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    Quote Originally Posted by John VM View Post
    You need to expand up a thou more or find a mandrel 1 thou smaller. You don' want the brass to tight or everything gets to hot and it starts to change all your dimensions through expansion.
    John
    If I do this I'm afraid the arbor would be loose on 80%% of the neck and then a slight interference fit over the last 20%. (Those percentages are guesses on my part)

  12. #12
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    ""My problem is getting the turning arbor in far enough to get the cutter into the brass.""


    If you're at 0.243 then you expand with a 0.242 mandrel and turn with a 0.241 Even with a carbide mandrel I find it useful to lube the case neck and I prefer resizing wax.
    Last edited by antelopedundee; 10-28-2022 at 10:11 PM.

  13. #13
    Join Date
    Feb 2003
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    Wichita Falls, Texas
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    Lightbulb What neck turner/system are you using?

    Are you using a "matched" expanding mandrel, prior to turning?

    The K&M system offers a carbide turning mandrel that also incorporates internal cutting flutes, that eliminate "donuts".

    Note.....I inspect each turned case, to insure that my set-up is actually producing necks that are within 0.0001" T.I.R.

    Hope this helps.

    Kevin

  14. #14
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    Quote Originally Posted by 10ring View Post
    I'm having a little trouble when I turn the necks on some Lapua 220 Russian brass which has had the neck expanded up to 6mm. The turning Arbor starts into the neck with a slight amount of interferance, (which is good), but when the Arbor gets in far enough to be at the neck/shoulder junction it requires a lot of force to push it past this point.

    Am I doing something wrong or missing a step?
    After expanding, the lower portion of the neck is what used to be the upper shoulder area. Consequently, the I.D. of the lower portion of your newly expanded neck is going to be smaller than the I.D. of the upper part of the neck.

    You can call it a 'donut' or a 'funnel' shape to the inside neck. Regardless, a perfectly round turning mandrel will never fit well.

    I make the inside of the necks perfectly round and straight before turning.

    Good shootin' -Al

  15. #15
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    Quote Originally Posted by Al Nyhus View Post
    After expanding, the lower portion of the neck is what used to be the upper shoulder area. Consequently, the I.D. of the lower portion of your newly expanded neck is going to be smaller than the I.D. of the upper part of the neck.

    You can call it a 'donut' or a 'funnel' shape to the inside neck. Regardless, a perfectly round turning mandrel will never fit well.

    I make the inside of the necks perfectly round and straight before turning.

    Good shootin' -Al
    How do you do that, Al?

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