Seeking a good source for expanding mandrels

Discussion in 'Reloading Forum (All Calibers)' started by Mulligan, May 19, 2017.

  1. Mulligan

    Mulligan Silver $$ Contributor

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    Where is a good source for expanding mandrels?
    CW

    Edit
    Explanation, I have a Sinclair expander die and several of the basic expanders for turning necks. I would like to test with different mandrels to "tinker with" neck tension.

    CW
     
    Last edited: May 19, 2017
  2. JLT

    JLT Gold $$ Contributor

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    K&M - https://kmshooting.com/

    Or you can get gage pins in whatever size you want. I went this route for expanding necks before seating the bullet. Inexpensive and a great way to experiment with different neck tensions.
     
  3. Chuckhunter

    Chuckhunter Silver $$ Contributor

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    2nd for K&M, will grind whatever size you request.
     
  4. hrlincoln

    hrlincoln

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    21st Century
    http://www.xxicsi.com/
     
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  5. Mulligan

    Mulligan Silver $$ Contributor

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    Exactly what I am wanting to do.

    Edited to include question.
    Once you identify the size needed/wanted is there a source for a carbide mandrel?
    CW
     
    Last edited: May 19, 2017
  6. JLT

    JLT Gold $$ Contributor

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    As Chuckhunter mentioned, K&M will grind to your specs. Do you really need carbide for neck expansion? Tool steel would do just as well, last as long for practical purposes (likely to outlive us all) and cost less. I'd go with tool steel and keep some dry graphite handy. My two centavos . . .
     
  7. T-shooter

    T-shooter

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    JLT, what's your feelings about using dry graphite when seating bullets? I recently started using the Imperial (Convenience Pack) on the ends of the cases after pulling some loaded rounds apart and finding maybe 1 out of every 15-20 were stuck. Those were Hornady cases and all prepped at the same time and in the same way. I just pulled 100 Lapua cases to alter the powder charge and noticed a few snug but not stuck like in the term "cold welding". If I hadn't pulled them apart, I would have never know I had a problem except for unexplained fliers or random over pressure signs.
     
  8. mikecr

    mikecr

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    Neck tension is spring back against seated bullet bearing.
    You don't adjust spring back to area with different size mandrels, different size bushings, or friction changes.
    I just think you should consider & understand this before venturing into pure lost.
     
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  9. Joe R

    Joe R Please don't send me PMs, I prefer e-mail Gold $$ Contributor

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    Here's my response to a different post:


    I know that everyone likes to control neck tension with bushings but to me that doesn't seem like a very good way. From my way of thinking bushings transfer any variance in neck thickness to the inside of the neck where they have a direct impact on neck tension. That is not a good thing, because no matter how careful you are turning necks there will be variances, and those variances will impact neck tension.

    I believe that the outside of the neck has minimal importance. The only important thing is how thick the necks are because that has an influence on spring-back. IMO the part of the neck everyone should be focusing on is the inside of the neck, or more appropriately inside diameter. The inside diameter is what influences neck tension, if one can transfer neck wall variances to the outside of the case it is that much better.

    So the question is how do we control neck tension from the inside of the neck? What if instead of honing die necks (an irreversible and often problematic process because dies are hardened, not to mention that you have to be twice as accurate with a die then with a mandrel, an impossible taskfor most small machine shops) we were to use a mandrel to expand the necks to provide the desired neck tension? What would a mandrel do?

    Well, ... a mandrel would control the inside diameter of a case neck much more precisely than any bushing ever can. It could also transfer neck thickness variances to the outside of the neck where it doesn't interfere with neck tension and bullet release. That's good isn't it?

    I have been using mandrels for thousands of cases. The problem is that just when I have a mandrel that gives ideal neck tension (down to .0001 precision) it starts to wear, and after a couple of thousand cases it is done. Making another mandrel to .0001 precision is very difficult/not possible for most machine shops and grinding shops. So I set out to look for a solution. I eventually focused on the Hornady bullet puller collet, because that's what I had. I started using the bullet puller to hold pin gages to expand the necks to match the turner mandrel.

    However, the bullet puller did not hold the pin gages as co-axially straight as I wanted, so I approached Kenny Porter, who is master machinist for all kinds of things including parts for pacemakers (can you think of anything more critical?). I told him I wanted him to make a die for me that would hold a pin gage, actually a range of pin gages ie .305, .306, .307, .308 and .309. Once I showed him what I had in mind he made a leap to a collet that is ideally suited for what I wanted. The collet holds the cutting bit for a CNC machine. It has real holding power.


    Pin gages are small tubes 2" long and can be bought for a few dollars and they are available in dimensions as exact as .0001 (+/- .00002). They generally have a 60 to 62 Rockwell hardness, like tool steel. They are ideal for this purpose, all you have to do is bevel the tip.


    Well, ... to make a long story short Kenny Porter (kennethp@portersprecisionproducts.com) made this die for me . The collet he used is made for CNC machines so it holds mandrels perfectly straight with great strength. This mandrel die makes all other mandrel die I have seen or bought look primitive.

    Regards

    Joe

    Neck expanding die 1.JPG Neck expanding die 2.JPG Neck expanding die 3.JPG Neck expanding die 3.JPG
     
  10. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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  11. LHSmith

    LHSmith

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    This simply is not true. With a Quality made neck turner judiciously matched with the appropriate sized expander, and after a considerable learning curve most competitors can achieve uniform results to the tenth (0.0001") with tools widely available from 21st Century, Sinclair, and K&M . It's not rocket science....just takes a meticulous attention to detail, doing the procedure exactly the same each time using the same tools, lube, speed and feed under controlled temperatures......and allowing sufficient time to do the job properly. Reloading for competition should never be a race if one expects precision made ammo.
     
  12. Joe R

    Joe R Please don't send me PMs, I prefer e-mail Gold $$ Contributor

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    Get real.
    The best I've been able to achieve is .0003 and I would challenge anyone to produce the results you just mentioned with those tools. I have had them all at one time in my journey. You must be a better man me.

    Since I can't see you profile, I'm just curious to know what kind of shooting do you do and where? I looked in the NRA High Power record holders and your name is not mentioned anywhere, which is a real surprise given that level of reloading skill.

    Regards,

    Joe
     
  13. damoncali

    damoncali Gold $$ Contributor

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    You can get to +/- .0001" if you put in the effort. Turning by hand helps, as does a lot of patience and a willingness to scrap cases. That's my experience at least. I don't bother without all that and get within +/- 0.0002" without much effort. I would guess roughly half are +/- .0001", and a few are +/- .0003" in any given batch.
     
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  14. mikecr

    mikecr

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    Joe, I like your mandrel die approach, and I agree that driving thickness variance outward reduces seated runout as measured off exposed bullet bearing. Neck expansion has always been part of standard neck sizing. A mandrel just does it better(inducing less TIR), and I refer to this as bullet pre-seating.
    But interference fit, which is what you set with either bushing, mandrel, or both, is not tension. You don't adjust tension with a mandrel. So this is not a selling point of mandrel use.

    Tension is adjusted with a bushing, by setting length of neck spring back(counter sizing) against seated bearing. This is a benefit potential of bushing neck sizing rarely understood or mentioned.
     
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  15. LHSmith

    LHSmith

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    My profile page is open to all and always has been. I have been posting my competition experiences on this site after I started IBS Score competition in '03 here in the N.E.
    #1. You bought a reloading tool that is not part of a "system". Every decent neck turner manufacturer offers a mating expander. They do the work so you don't have to re-invent the wheel. If you want to tweak the "fit" to the mandrel, K&M offers custom sizes.
    #2. In your posts and video, your main focus seems to be on getting the chore done as quickly as possible. As I mentioned that will never result in obtaining consistency.
    #3. Do what works for you. If you feel 0.0003" neck wall variation is no detriment to your FTR scores and have total confidence in your ammo that is all that matters.
    # 4. If you actually read the various nuances and steps other members have posted you have at your disposal a lot of free information that many of us have learned from lots of trial and error and trashed cases.
     
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  16. Mulligan

    Mulligan Silver $$ Contributor

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    Mike, would you please elaborate on your last paragraph?

    My entention is to experiment with different sized mandrels (to alter/adjust tension, grip, fit?) as the last step prior to seating bullets.
    CW
     
  17. Joe R

    Joe R Please don't send me PMs, I prefer e-mail Gold $$ Contributor

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    LH,
    Maybe its just me but this is what I get when I click on your name:
    Joe

    Capture.JPG
     
  18. jpmimproved

    jpmimproved

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    OP:

    I have used K&M mandrels to adjust the grip on the bullet as you have mentioned. I use both Forster and Redding full length sizing does, but have pulled the expander ball as they tend to be where I feel the greatest resistance while sizing. When I was working up loads today for .223, after passing it through my Redding die, the neck was sized down to ~.240, then I passed it over my K&M mandrel after using dry graphite lube on the inside of the necks. I ground the K&M mandrel down a while back for Norma brass in particular to give me a neck at .246 before loading a bullet. With Berger 80 VLD I have .0015 neck tension. This, to me does essentially the same thing as using a bushing die, but all the inconsistencies in the neck are pushed to the outside, giving me a more consistent grip on the bullet(in my opinion).

    Please note that the only evidence I have of success with this is that my groups are MUCH better than I had previous, but I also changed several components, so it could be multiple factors leading to this.
     
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  19. LHSmith

    LHSmith

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    It is not my intention to hide much of my personal info from members. What do you want to know?
     
  20. mikecr

    mikecr

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    Mulligan, the association with interference fit as tension is wrong. Anyone here could test it quick and see it.
    Size a neck to any interference fit greater than spring back(>1thou), seat a bullet, measure outside neck diameter. Now pull the bullet and remeasure neck OD. It sprung back ~1thou max. That is your tension, and it applies as a force to the bullet area it's gripping. The greater the area gripped(seated bearing), the greater the tension. With seated bearing established through seating testing (for best), tension is then adjusted by length sized to spring back against that bearing.
    When you adjust the sizing length beyond seated bearing (FL sizing of necks), you then put a huge binding force against the small area that is base-bearing junction. This removes all 'adjustment' of tension, and merely sets it to an extreme with variances greatly amplified by any donut variance. I would never do that.

    You can adjust the length of neck sizing with a bushing die. Set the bushing size to provide for ~2thou under cal, and then mandrel pre-seat to expand the necks to cal, from which they will always spring back below cal with mandrel exit. Ready for bullet seating.
    If you attempt to adjust tension with upsizing, instead of downsizing, what's the difference?
    Neck downsizing followed by expansion has been the neck sizing standard longer than we've been alive. The wheel is already on every car.
    Not suggesting that we can't improve it, but I am suggesting that would begin with understanding.
     

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