Neck tension control- turning vs expander mandrel

Discussion in 'Reloading Forum (All Calibers)' started by rimfiremac, Jul 11, 2019 at 9:59 AM.

  1. rimfiremac

    rimfiremac

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    Assuming proper annealing every firing, what works better for controlling neck tension uniformity when processing brass?

    Neck turning and using a bushing sizing die

    or

    Using an expander mandrel step after the re-sizing step
     
  2. 47WillysGuy

    47WillysGuy Gold $$ Contributor

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    I use a necking turning process to ensure all case necks are the same thickness(0.014”).

    Then once that process is completed, I move to my next process of squeezing the necks to an internal neck diameter of about 0.001” less than my projectile diameter.

    I cut the necks to my desired thickness, then size the case necks, then mandrel the necks to square the necks to case body and it also sets the interference fit of projectile to case neck and then finally checking the runout of the case necks with a dial indicator.

    I use Lee collet die because my bushing die gives me more runout than I care for.

    Invest in a dial indicator and it will tell you what works best for your application. Probably most used tool on my bench. Search on and good shooting.
     
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  3. Joe R

    Joe R Gold $$ Contributor

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    I made this video just for you. :)

     
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  4. mikecr

    mikecr

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    You don't have to turn necks to use bushings or mandrels. You can bushing size unturned necks and mandrel expand to drive thickness variance outward. The mandrel is not really needed for tension, as you can set proper 1thou under cal with a bushing alone. But it doesn't hurt to go to 2thou under cal sizing and then mandrel expand.

    It's unlikely you would need to anneal so often, and you shouldn't unless a developed load under that condition (low tension) likes it.
     
  5. David Christian

    David Christian Gold $$ Contributor

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    I don’t think those choices are mutually exclusive. What are your exact case prep steps now and what are your ES and SD results?
     
  6. rimfiremac

    rimfiremac

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    I'll hang onto my hat for the blasphemy calls I may get, but here's what I do:

    Uniform new brass with a Hornady neck sizing die (the generic one)
    Neck turn to 0.013 (I've found this to work well on both Winchester and Lapua brass)
    Load and fire

    After firing:
    Vibrate with corn media
    Anneal the archaic way (hand held, ~8 second dwell time, monitoring coloration)
    Redding competition neck sizing die
    Redding body die
    Load and fire

    I'll use this process for all calibers I load for. For instance, in 6.5 SKAN, I'll use Lapua brass, Murom LR primer, H4350, 139 Silver Scenar and get SD's running between 8 and 15 fps on a Magnetospeed, accuracy is 1/3 to 2/3 min at 300 yd, which is likely my own limit.

    My curiosity is whether there's any effeciency to be gained by omitting neck turning and instead, anneal, neck and body size, and then uniform tension with an expander mandrel.
     
  7. watercam

    watercam Gold $$ Contributor

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    !!!!! Or loose the expansion ball and just choose the correct bushing for your needs and set neck tension when you size the case (which should always be full length with a .001" shoulder bump). Adding steps, such as opening with a mandrel, only works the brass more than necessary. After over 20 years of Long Range competitive shooting and getting upwards of 25 firings from my brass I'll stick to the 'Less is More' version of reality.
     
  8. bigbulls

    bigbulls

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    Joe R,
    Where can a person get one of those pin gage holder for neck expanding?
     
  9. Joe R

    Joe R Gold $$ Contributor

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  10. 47WillysGuy

    47WillysGuy Gold $$ Contributor

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    I use a RCBS bullet puller.
     
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  11. rimfiremac

    rimfiremac

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    Roger, that's straightforward and simple
     
  12. D-4297

    D-4297 Silver $$ Contributor

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    The omitted information I'd like to know is :
    Are your chambers standard SAAMI diameter necks , or are they custom ? Never saw anything to be gained turning necks if you have a standard , ( No Turn ) neck diameter chamber , and a whole lot to be lost if you turn brass for a standard neck chamber . Creating excessive neck clearance , and thinning the brass at the neck improves , what ? There is already a ridiculous amount of clearance on a standard sized neck chamber .
    Using a expander die for standard chamber neck brass will force any "imperfections" towards the outside and make for a smoother , more concentric I.D. to seat your round . I use a bushing to take my .308 I.D. down to .305 , and a .3075 mandrel to go to a .307 finish size . Thirty-five years as a Master Die-maker tells me that is not over-working annealed brass . But hey ...everybody has "their" way to do things .
     
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  13. antelopedundee

    antelopedundee

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    FWIW you can buy boxes of 25 bubble pack envelopes at Sam's Club pretty cheap.

    Thanks for the info about residence time of the case in the sizing die. Can't say that I've ever given it any thought nor can I recall ever having seen it mentioned elsewhere.
     
    Last edited: Jul 13, 2019 at 12:09 PM
  14. antelopedundee

    antelopedundee

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    For those of us who don't use a powered system to turn necks it would be nice to have a cutter that cuts a wider swath.
     
  15. antelopedundee

    antelopedundee

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    Have you ever loaded sized cases right after sizing and given some like 24 hours to relax after sizing before loading and seeing if there's a difference [assuming that conditions are such that any difference can be determined?

    Take 10 cases and size by removing the sized case from the die as quickly as possible. Load 5 right away and the other 5 24 hours later.
     
  16. antelopedundee

    antelopedundee

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    If a .014 thickness setting doesn't remove any brass do you scrap the cases or adjust the cutter to give a thinner neck like say .012?

    I have some PPU cases where brass removal was small even at about a .012 setting.
     
  17. Bradu

    Bradu

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    For the two calibers I turn, I set it to the thickness I want and turn off what needs to be removed. I don't worry about the spots that aren't touched by the cutter.
     
  18. Richard Coody

    Richard Coody Gold $$ Contributor

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    Well in my opinion neck turning and using a mandrel to set final neck tension are two completely different processes. There is no either or.

    If you are shooting a quarter moa rifle and looking for another 0.10 less in group size. They may help. Otherwise you are just.wasting time and money.

    Neck turning accomplishes 2 different issues.

    You can have a consistent neck thickness for the entire diameter of the case. This helps with concentricity and consistent neck tension

    If you have a custom tight neck chamber you most likely will have to neck turn. You can easily decide just what kind of neck clearance works best for you in your barrel.

    As for using an expander mandrel for final neck tension. I have the k&m kit in .0005 increments. I have found by using this system just before loading the brass i can get very consistent neck tension measured with a 21st century hydro press.

    Do you really want to go down this rabbit hole. I doubt it.
     
  19. antelopedundee

    antelopedundee

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    What if none of the neck is touched at your desired setting? How thin are you willing to make them?
     
  20. Bradu

    Bradu

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    I set it so I have .004" clearance in the chamber with a loaded round. If the brass measured fine, I wouldn't neck turn. In your situation, I would use an expander mandrel vs neck turning.
     
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