Neck tension?

Discussion in 'Reloading' started by KiloTango, Aug 10, 2013.

  1. KiloTango

    KiloTango Active Member

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    Original variables:
    0.289" loaded neck diameter.
    0.287" bushing.
    New brass sized to 0.2875".
    Got great groups.

    Once fired neck diameter 0.293"
    Using the same 0.287" neck sizer that I used on the new brass got me 0.289" after neck sizing. I could move the bullets in and out of the case with little force.

    Got a 0.285" bushing thinking I'd get 0.002" spring back. The 0.293" once fired brass came out of the 0.285" bushing 0.286". Guess spring back is not linear.

    Will that 0.0175" difference make a significant impact? The 0.286" bushing is back ordered...and I'm not near max load at all.

    Thanks,
    Ken
     
  2. barnesuser28

    barnesuser28 Well-Known Member

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    Sounds like your brass might need annealing.
     
  3. Mikecr

    Mikecr Well-Known Member

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    He don't need annealing after a single firing.
    I think he's on the right path as bushing sizing can be a bit of trial & error, when sizing so much.
    But I recommend expanding necks to desired using Sinclair expander mandrels, instead of with sizing die buttons, or no expansion.
     
  4. woods

    woods Well-Known Member

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    Hey Mike

    Sinclair says

    " Our neck turning tool mandrels measure approximately about .002"" less than the bullet diameter for the caliber. Our expander mandrels are made .001"" larger than the turning mandrels."

    So that would make the expander mandrels .001" less than bullet diameter

    So a good method would be to size with the bushing die smaller than caliber and then use the expander mandrel?

    Is there a best case scenario for the size to size the case down to with the bushing. IOW size the ID down to .003" below caliber and then use the expander. Or .002", .004"? Or does it matter at all?

    Don't want to hijack the thread, but I have a 375 Ruger full length die that sizes the ID down to .361" without the expander. Would it be beneficial to get a Sinclair die and expander mandrel? Or is that too much expansion to get good results?

    BTW KiloTango, not nitpicking but I think you're mission a zero

    .2875"-.286"=.00175"

    That .286" should give you .003" bullet grip which I shoot all the time and prefer. As long as it does not cause runout from too much seating pressure, which you can aid with dry lube, a good chamfer and a good seating die.
     
  5. TOM H

    TOM H Well-Known Member

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    Are you turning necks?
     
  6. Mikecr

    Mikecr Well-Known Member

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    It's better to size correctly, leaving the actual bullet with less work on seating. This allows more precision in seating as there is less wedging variance from the seater stem on bullet noses from higher seating forces. If you need to pre-expand to get there, Sinclair's mandrel system is top notch.

    You can choose the right bushing to put neck IDs 1-2thou under cal and be done with it. I pre-expand anyway for straighter seating(to reduce loaded runout) as bullets make terrible expanders(too soft).
    With most chambers I go under 2thou with a bushing(after springback), and then my expander leaves me ~1.5thou under cal. This is plenty and sizing more only serves to change brass hardness.
    It can be trial & error to get here depending on thickness/hardness of brass.

    I'm sure you mean ID down to .371(not .361). The expander mandrel would be .374 and this would leave your IDs at .373(2thou under) after springback.
    Would work really well.
     
  7. KiloTango

    KiloTango Active Member

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    Yes, I am neck turning.
    6.5x47 Lapua
    Saami specs say loaded rounds should have neck diameters of 0.291"
    Used a Sinclair expander to get every neck round (the shipping dented some necks), and to get them all the same diameter.
    Skim turned neck walls to 0.0125".
     
  8. woods

    woods Well-Known Member

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    No .361"

    [​IMG]

    So I just resized another one in the FL die without expander and it came out .362", tight on the pin gauge, had air resistance inserting and extracting pin gauge from neck since not deprimed yet

    [​IMG]

    Do you think that the expander mandrel would still leave the neck at .373"?

    Need to get rid of that expander ball. Normally would order a Lee Collet but haven't got around to it yet. The Sinclair expander would be something new and maybe I'll learn something. But if that is too much expanding and would have other ill effects, then I'll have to order die or get this one honed out
     
  9. Mikecr

    Mikecr Well-Known Member

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    Woods I must be misunderstanding. A 375Ruger uses bullets .375" dia right?
    Are you using .366" dia bullets?
     
  10. woods

    woods Well-Known Member

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    No I'm posting correctly. The die is a Redding 375 RUGER FL X8 and the brass is Hornady 375 Ruger new case. The expander ball is .373"

    The brass is a little thick and averages .014". I could gain a little by turning all down to .012" but that would only increase the ID by .002"

    So you think someone at Redding made a mistake?
     
  11. TOM H

    TOM H Well-Known Member

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    I had tight neck 6.5x284 and have .286 redding carbide bushing. If you want PM and I'll send you that bushing and when you get yours just send it back.
     
  12. 8andbait

    8andbait Well-Known Member

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    Very Cool
     
  13. Mikecr

    Mikecr Well-Known Member

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    Absolutely. sizing 14thou under cal is what you do when forming a wildcat to next smaller cal.
    It's in no way normal neck sizing.

    I have never heard of so much neck sizing while staying within cal.
    You should be sizing necks no more than 3-4thou under cal.
     
  14. woods

    woods Well-Known Member

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    Mike

    Pm sent to stop hijack