New neck expander/bullet tension/accuracy

Discussion in 'Reloading Forum (All Calibers)' started by mousegunner, May 22, 2020.

  1. mousegunner

    mousegunner

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    I received a new expander with a new decapping stem for my Hornady .223 dies. The new expander is .002 larger than the old one. I measured 2 cases using each expander and the difference was .002 outside neck diameter.

    Now since I can't shoot yet would there be an accuracy difference between rounds using the larger and smaller expander given the difference in neck tension?

    I want to use the old one that will give me a tighter grip but maybe I should start with new one that doesn't have thousands of rounds through it. A trip to the range will tell but what are your thoughts?
     
  2. bozo699

    bozo699 Gold $$ Contributor

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    Anytime you change neck tension it’s going to effect accuracy it may be in a positive way or negative way. The bigger question would be with .002 less neck tension do you have enough to hold your bullet during recoil in your magazine?... what rifle are you shooting and what are you doing with it?
    Wayne
     
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  3. mousegunner

    mousegunner

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    It's my AR match rifle for across the course. It's been a sub MOA rifle with my loads. Maybe I'm over thinking this but without range time I'm just curious what any difference will be.
     
  4. bozo699

    bozo699 Gold $$ Contributor

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    So with the new die how much neck tension will you have?
    Wayne
     
  5. Ned Ludd

    Ned Ludd Gold $$ Contributor

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    What were the actual measured O.D. values using the old and new expanders? What brand of brass are you using? What was the neck O.D. after seating bullets with the old expander? These are the numbers we really need to make useful suggestions. IMO - .002" difference (decrease) in neck tension (interference fit) might actually be a HUGE difference, especially in a relatively small cartridge like the .223 rem. However, that would depend a lot on where it was with the old expander.
     
  6. jepp2

    jepp2 Gold $$ Contributor

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    You can chuck it up in a drill and reduce the diameter pretty quickly.
     
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  7. mousegunner

    mousegunner

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    This is Speer brass.

    OD on neck for old expander .244
    After seating bullet .248

    OD on neck for new expander .246
    After seating bullet .248

    So my neck tension is .004/.002? Am I looking at this right?

    Seating felt just a little tighter on case with .244 OD than the .246.
     
  8. BDman

    BDman

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    In theory, your NT should be reduced with the new expander. But, with that after seat diameter being the same, it did not change. Just one more example of how difficult it is to measure NT. Do you crimp after seating? If so, that could explain the final measurement being the same. My .02.
     
  9. bozo699

    bozo699 Gold $$ Contributor

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    Huh?.....
    The measurements after seating is never going to change unless he neck turns or uses a smaller bullet.
    He’s went from .004 neck tension to .002 neck tension. Shooting in matches on a AR platform may not be enough idk I don’t like ar’s so I don’t shoot them but I would definitely do so checking to make sure my bullet is not moving under recoil in the magazine. My gut feeling is it’s on the ragged edge, may hold may not but at any case it needs checked out!
    Wayne
     
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  10. mousegunner

    mousegunner

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    No crimp and I've run ammo from these dies through 3 different ARs. I can press the round hard against my bench and it doesn't set back for what that's worth.

    I've got lots of processed brass with the old expander, I'll resize a batch with the new expander and see how it compares at the range.

    I only asked Hornady for a replacement decapping stem but they included the new expander as well so my question came up. I've had these dies for 10 years, they wouldn't take my card and sent the parts under warranty, hats off to Hornady.
     
  11. BDman

    BDman

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    Correct, bozo, I was thinking after sizing instead of after seating. Think/spoke wrong - not enough coffee yet. I went to pin gauges for measuring NT and haven't measured the other way in a while. I prefer .003 on AR's. A force gauge seater for exact number or put the tip against your bench and if you can easily push the bullet deeper, you haven't got enough.
     
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  12. bozo699

    bozo699 Gold $$ Contributor

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    Good luck my friend and shoot well!... I’m not a huge Hornady fan on most of there stuff,not all but most I do like there bullets but good customer service is hard to beat I’m glad they treated you well
    Wayne
     
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  13. Uncle Ed

    Uncle Ed

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    mousegunner, what is the actual diameters of the two expanders?
     
  14. Ned Ludd

    Ned Ludd Gold $$ Contributor

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    That's a pretty large difference in neck tension/interference fit, IMO. It will likely be enough to change the properties of the load (i.e. pressure, bullet release, neck sealing, etc.). On the positive side, you're working the brass a bit less. In my hands, .002" neck tension may not seem like much, but it is sufficient that I can't move a bullet in the neck with fingers only, it actually takes a couple pair of pliers holding the case and the bullet, so the bullets should be in the neck pretty tight even at only .002" neck tension.

    However, if you're running rounds from a mag or letting the bolt slam home on single-fed rounds, bullet seating depth can change as that happens with .002" neck tension. Using cannelured bullets with a crimp would be one way you could address this if it turns out to be a noticeable problem. Alternatively, if the change in bullet seating depth as the bolt slams home is consistent, it may not matter much. Is it possible to screw the old expander onto the new shaft? I'm guessing you already looked into that. When you are able to get out and shoot, the simplest thing may be to just see how well rounds using the newly prepped brass shoot, and adjust the load if necessary. If you adjust the velocity back to what it was previously, then do a seating depth test, you ought to be able to get the load shooting very close to what it was previously.
     
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  15. mousegunner

    mousegunner

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    Old is .221
    New is .223
     
  16. mikecr

    mikecr

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    Are you FL sizing the necks?
    How deep is bullet bearing seated?
     
  17. jepp2

    jepp2 Gold $$ Contributor

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    You don't mention how much you die undersizes the case neck (neck OD after sizing with the expander removed). I don't run any expanders that are 0.223". Just not enough neck tension.

    Probably an obvious reason, but why can't you just switch expanders so you use the same one you have been?
     
  18. mousegunner

    mousegunner

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    FL sizing the necks, bullets are 55 FMJs, 69, 77, and a few 80s BTHPs, seating according to each type, mostly mag length. I don't leave em hanging so to speak.
     
  19. mousegunner

    mousegunner

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    Haven't measured necks without expander after sizing so.....anywho I had every intention of using the old but since the new one was included it just got me thinking.
     
  20. Uncle Ed

    Uncle Ed

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    Many reloaders use the Lyman type "M" expander for their AR15 rifles and bump the case mouth onto the .226 section. This aids straight inline seating and reduces neck/bullet runout. If needed a taper crimp die can be used to close up the case mouth for proper feeding. Normally after brass spring back the case mouth is only .001 larger than bullet diameter. My main point being the Lyman expander is .221 and .003 smaller than bullet diameter.

    [​IMG]

    Below is from a test of .223 resizing dies and how much they work the brass, And you can see the inside diameter of the case neck using the expander and the amount of bullet grip.

    [​IMG]

    And below the RCBS AR Series dies come with a taper crimp

    [​IMG]
     
    Last edited: May 23, 2020
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