Calculating Type S-Neck die size?

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  • Calculating Type S-Neck die size?

    Can anyone confirm this is the way to calculate the size of type S dies.

    Calibre 6.5mm .264
    Neck thickness .015
    Outside neck diameter .264 + (.015x2) = .294

    Take off a thou for tension, die size required .293

  • #2
    Yep, you are correct.

    If you are going with a magazine fed rifle you should take another thou or two off to ensure the bullet does not move under recoil.

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    • Guest's Avatar
      Guest commented
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      On my phone ATM but if you look it up on the redding site it explains the method for calculating.
      There is also a YouTube on it as well from redding.
      Adamjp is correct though.
      I normally buy 2 sizes, one that is a bit light on tension & 1 thats another thou tighter.

  • #3
    Thanks guys,
    I figured it would be online somewhere, still can't find it though
    I just need to find out what the chamber neck size is going to be now, I have a feeling it's .294 which isn't going to give much clearance.
    I was hoping to avoid neck turning but it looks like a I may have to.

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      To get an approximation of your chamber neck diameter measure the diameter of a fired shell and add about 1 to 1.5 thou. I run 2-3 thou neck tension - often i find you get slightly lower runout with lower neck tension for some reason but my loaded rounds are still more accurate with higher neck tension (even though runout averages higher?)

    • Pitty
      Pitty commented
      Editing a comment
      Originally posted by tinytim" post=17566
      Thanks guys,
      I figured it would be online somewhere, still can't find it though
      I just need to find out what the chamber neck size is going to be now, I have a feeling it's .294 which isn't going to give much clearance.
      I was hoping to avoid neck turning but it looks like a I may have to.
      Here ya go.http://www.redding-reloading.com/tech-line-a-tips-faqs/140-bushing-selection

  • #4
    Originally posted by tinytim" post=17466
    Can anyone confirm this is the way to calculate the size of type S dies.

    Calibre 6.5mm .264
    Neck thickness .015
    Outside neck diameter .264 + (.015x2) = .294

    Take off a thou for tension, die size required .293
    NO.....!!!!!!

    Die size...???? or more likely are you referring to Die Bushing Size.....????

    It is very doubtful that the case neck measures .015" overall for a start perhaps a fraction under BUT if you are using Lapua cases it might be more correct at 0.0135" to 0.0140" or less for neck thickness measured correctly with a Ball Neck Micrometer.

    The best way to determine a bushing size, and I think that is what you are asking is to seat a bullet in a case and measure the loaded diameter of your round. That can be done in a new factory case easily.

    I have a feeling that your seated bullet in the neck of your case might be more like 0.291" or less. So, that means a bushing size of 0.289" or less to give a maximum of 0.001" neck tension after spring back. You may probably need to go smaller if you want more neck tension.

    There are a number of bushing manufacturers, one like Wilson make "Tapered" Bushings the others may be straight cut but...also their designated size is not always correct so you will most likely have to adjust your size in real terms.

    I am basing my measurements on new Lapua 6.5 x47 Lapua Cases so I don't know which 6.5mm Case you refer to.......

    I don't know what Adam has been smoking but what does a magazine have to do with neck sizing dies....???? or perhaps thinks that something 6.5mm Calibre is a heavy recoil calibre. I think TT may be playing with a .260R or similiar and doesn't need the world of neck tension.

    Anyway, I have had two Redding Titanium Bushings here of the same stamped dimension and they are different by 0.001" so it is still trial and error.

    Comment


    • Pitty
      Pitty commented
      Editing a comment
      Of the 3 different brands I have in 260r, they measure loaded
      Nosler = .289
      Norma = .289
      Remington= .291
      All loaded with the same projectile
      Fired Case = .299
      The neck bushing I use is .287

  • #5
    It all depends on how thick the neck walls are . A new batch of brass may stuff up the whole sizing setup.
    A bush selected for .001 reduction may result in very low neck tension if new brass has thinner necks and more tension if new brass has thicker necks . So without neck turning to specific diameter all the time one bushing will possibly not be enough if multiple brands of brass are reloaded .
    If you are not neck turning then I recommend you buy 3 bushings .001 .002 .003 reduction on your present loaded round diameter this gives you some adjustment for varying brass .
    The Redding technicians advice of only reducing .001 is only right for very specific circumstances on certain thickness brass.
    It does not allow for the neck tension required for Autos , Pump actions , big magnums , etc that .001 may not be enough to adequately hold the projectile . Thats the sh*tyist advice I have seen on the subject because it's just not in depth enough .
    Neck tension has to suit the type of ammo and the use it will be put too and in what type of gun .

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      Originally posted by Happy jack" post=17689
      It all depends on how thick the neck walls are . A new batch of brass may stuff up the whole sizing setup.
      A bush selected for .001 reduction may result in very low neck tension if new brass has thinner necks and more tension if new brass has thicker necks . So without neck turning to specific diameter all the time one bushing will possibly not be enough if multiple brands of brass are reloaded .
      If you are not neck turning then I recommend you buy 3 bushings .001 .002 .003 reduction on your present loaded round diameter this gives you some adjustment for varying brass .
      The Redding technicians advice of only reducing .001 is only right for very specific circumstances on certain thickness brass.
      It does not allow for the neck tension required for Autos , Pump actions , big magnums , etc that .001 may not be enough to adequately hold the projectile . Thats the sh*tyist advice I have seen on the subject because it's just not in depth enough .
      Neck tension has to suit the type of ammo and the use it will be put too and in what type of gun .
      I wouldnt go with 0.001 anyway - one because I run compressed loads (and the bullet would just pop straight back out!) and two because many people report that their ES tends to be lower if they have more neck tension

      having said that the short range benchrest guys say they can get excellent score with high ES's? I'm guessing a slightly higher neck tension is better for long range stuff

  • #6
    It's easy...
    Buy a bushing smaller than your loaded round. Depending on the grip you want will depend how much less the bushing needs to be. Allow for a small amount of spring back in the case too.
    If it's a hunting rifle than the following example will be fine:
    .290 loaded round
    .288-.289 bushing

    The bushing allow you to not only control the amount of tension, but ensures you only size the brass as much as you need to to reduce the work hardening of the neck which therefore extends case life and maintains consistent neck tension for more loads.

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    • #7
      Thanks guys,

      My mistake, not enough info.
      6.5x284 target rifle (yes I know I'll only get 1000 rounds at best)
      Barnard P single shot.

      There is no Lapua available so I went Norma, all new brass and 0.015 neck thickness is accurate, some are close to .0145 but none are actually that low. I'll double check that at work though.

      There seems to be a bit of chicken and egg with regards to this. Measuring a loaded round doesn't seem to make much sense. That's like using an unknown as a datum point? Assuming no material is lost and there's no deformation, this size should be projectile diameter + 2 x wall thickness.
      I see the benefit of going down 2 thou to allow for spring back though. Only going down 1 thou won't give 1 thou crush.

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        Originally posted by tinytim" post=17735
        Thanks guys,


        Measuring a loaded round doesn't seem to make much sense. That's like using an unknown as a datum point? Assuming no material is lost and there's no deformation, this size should be projectile diameter + 2 x wall thickness.
        I see the benefit of going down 2 thou to allow for spring back though. Only going down 1 thou won't give 1 thou crush.
        On the contrary, measuring a dummy round is the best way to go IMHO. Remember to seat the bullet so the pressure band (if it has be) is in the neck. This way you can measure neck before and after seating to get an exact neck tension measurement.

        There is absolutely no point using neck bushing dies if you don't neck turn, you'll never have consistent neck tension.

        Steve
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