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Using 2 Seater Dies for Consistent OAL??

Discussion in 'Reloading' started by GhettoSmack, Nov 19, 2011.

  1. I've been a little frustrated lately in the amount of OAL variance in my 9mm loads.

    My first thought is to try bullets from different manufacturers to see which one(s) fit the seater die shape better, thus have a more consistent OAL.

    My second thought is to use a SECOND seater die. I have an empty stage on my XL650 just before the existing seater die. So I add a seater die to seat the bullets about 0.010" longer than desired. Then the 2nd seater die will seat to the desired depth as the "finish" die. (Next and final stage is crimp and full length resizer die.)

    My question is: Has anyone tried this setup before? If so, what were the results? If not, what do you guys think of such a setup?

    Thanks in advance for your thoughts and ideas!
  2. ron59

    ron59 Bustin Caps

    Jan 3, 2009
    Smyrna, GA
    The problem is probably your "full length resizer die" with lead bullets. You using a Lee FCD? If so, throw that away.

    BTW, Steve told me to tell you this.


  3. TN.Frank

    TN.Frank Glock4Life

    Oct 11, 2004
    Avondale, AZ.
    I always seat my bullets first then go back and crimp them in a separate step. You might give that a try but I'd not worry about it too much. .005" isn't all that much in the over all scheme of things.
  4. XDRoX


    Jan 24, 2009
    San Diego
    All my inconsistent OAL problems disappeared when I stopped measuring them.
  5. Cap'n


    Jul 9, 2009
    I, too, get annoyed at OAL variance, but for most of my handguns, it turns out to be a non-issue. YMMV.

    Before you go to lots of trouble, have you confirmed the amount of variance you get ACTUALLY (adversely) affects accuracy or functional reliability of your pistol?

    You could sort your existing ammo by OALs and shoot several groups of each OAL (or groups of small OAL variations) to see if there's any significant difference.

    For a really good test, it'd be nice to have someone else load the revolver or magazines for you without you knowing what OAL you were shooting. The loader would keep a record for you. This eliminates your own pre-judgements of the ammo's performance, e.g., "This is that crappy OAL, so I'll just pop these off without spending too much time on sight picture, etc."

    IME, tight OALs (minimal variation) is meaningful in rifles but much less so in handguns.
  6. Colorado4Wheel


    Nov 2, 2006
    Have you checked your shellplate to make sure it's as tight as possible with out binding?

    Seating and seating again seems silly. You got the best seating die made and if you do it in two steps your going to loose part of the advantage of that die. It cost around $80. I would try seating the same bullets with out that redding just for kicks as well. But your worried about nothing.
  7. scattershot


    Nov 15, 2010
    Denver, CO
    I worried about that, too, ubtil I measured several factory loads. Just shoot them and don't worry about it.
  8. Best advice, comment, observation I have seen today on GTR today.

    Some people just like to make things far more
    complicated than they need to be.
    Last edited: Nov 19, 2011
  9. Jim Watson

    Jim Watson

    Jul 10, 2001
    1. Get an RCBS seating die and send them a sample round to cut a custom seating plug for.
    2. "Glass bed" the seating plug in your existing die with epoxy to exacty fit the bullets you are loading.
    3. Don't worry about a little OAL variation in bulk 9mm.

    I selected Door No 3.
  10. F106 Fan

    F106 Fan

    Oct 19, 2011
    Some thoughts on this:
    • On a multi-stage press, the base will flex somewhat depending on how hard the resizing die is working. You will find OAL variations that are a function of how hard it is to resize a case.
    • When you measure OAL, what are you really measuring? Nothing more than the OAL (from the nose to the base) which has almost nothing to do with the shape of the ogive and where it is located in relation to the rifling. It MIGHT have something to do with the volume remaining in the case, or it might not, depending on the consistency of bullet length and the consistency of the cases. And without an optical comparator, you don't know anything about bullet consistency. You can do volumetric testing of cases but this is pistol shooting, not rifle shooting.
    • You can always do the seating on a single stage press which won't have any flex caused by other stations. A single stage press uses an inline action which doesn't allow for flex. You could also do it on the progressive press if you weren't resizing at the same time. But the multi-stage presses will always have more flex than a single stage press.
    • You could use a seating die that has a large flat portion that actually presses on the nose of the bullet. Most don't do it this way. They will have a rounded insert that probably doesn't fit the nose of the bullet (deliberately, to prevent damage to the nose) and they may have a flat insert that works well with SWC bullets.
    • Reloading without a chronometer is always a guess. Sometimes I get results that come close to published data, sometimes it is off by quite a bit. That variation may be because I don't have EXACTLY the same bullet or EXACTLY the same barrel. I NEVER have EXACTLY the same primer because I use only Federal. Sometimes I think the manuals are a little optimistic. But measurements are what they are; my gun, my load, my results. Even then, my chronometer measurements aren't calibrated and traceable to NIST. Who knows whether they are right or wrong? The only chronometer that matters is the one used at the match and I'll bet it isn't calibrated and traceable to NIST either. What about temperature variations in oscillator frequency? It's not like these devices use temperature controlled crystal oscillators (TCXOs). This whole thing is just a collection of guesses and if all the inaccuracies pile up in the wrong direction, you are disqualified.
    • All of this is pretty meaningless because a load that measures 130 PF or so will always make the grade. The target is large so pinpoint accuracy of the load itself is never a factor. There is no way a few thousandths variation is OAL will produce more than an inch difference in POI at 25 yards. But even then, how would you know? High speed shooting doesn't lend itself to measuring group size. Maybe with a Ransom Rest, a chronometer and a lot of time, all of these variables and their effects could be measured (at one specific environmental condition). But none of them are going to add up to a small fraction of the variation caused by a flash sight picture.
    • Once bullet seating is PERFECT, you need to do some statistical analysis on powder charging. These variations really do affect velocity and some powders meter better than others. NONE of them meter exactly from a volumetric powder measure. That's why precision rifle shooters weigh each charge. In my view there will be much more variation in velocity caused by powder charges than there will ever be from OAL. For 147 gr Berry's at 1.150" OAL and Titegroup powder, I get:
      3.2 gr - 864 fps 126 PF and 26 fps ES
      3.3 gr - 880 fps 129 PF and 34 fps ES
      3.4 gr - 900 fps 134 PF and 42 fps ES
      The extreme spread (ES) is all over the map. I get much better numbers with Bullseye and there are a lot of powders to test.
    That's about it! A few thousandths in OAL just doesn't concern me. I design in plenty of slack.

  11. Uncle Don

    Uncle Don Wood butcher

    Jan 24, 2004
    No way I could have said it any better.
  12. GioaJack

    GioaJack Conifer Jack

    Apr 14, 2009
    Conifer, CO
    Was I taking a nap when loading all of a sudden got this complicated? :dunno:

  13. ken grant

    ken grant

    Apr 3, 2004
    middle ga.
    The Ogive on the bullets can vary OAL and they do vary even in the same batch
  14. F106_Fan - Now you're talking my language! Engineer?

    To answer the questions:
    I am running an XL650 with Redding Competition Micrometer Seater Die. Berry's Plated 124gr RN 9mm bullets. The crimp die is a separate station and is a Lee Carbide Factory Crimp die. I use a shell plate bearing kit and a tool head clamp kit. And I already have a Dillon Carbide seater die which wasn't consistent with ANY bullet, which is why I bought the Redding.

    So what I am reading is that I shouldn't worry about OAL variance of +- 0.005. I should test the differing lengths to see if there is a difference in accuracy and speed. And no one has tried the two-seater die setup.
  15. Colorado4Wheel


    Nov 2, 2006
    Your using a cheap bullet and a Dillon with the most expensive seating die and every upgrade to make it as good as possible. Think about that equation and decide what you should change next. Remember I said in the other thread that I get much less OAL variation and I use a Lee Die. I cast my own bullets, I have the roller bearing and no toolhead clamp. But my oal variation is ussually .004 TOTAL (.002). Its your bullets or bad die setup.
  16. Uncle Don

    Uncle Don Wood butcher

    Jan 24, 2004
    Go back to sleep Jack - We'll send the nurse in to wake you when common sense kicks in.
  17. unclebob


    Oct 14, 2000
    Mary Esther FL
    Or become Rip Van Winkle.:tongueout:
  18. F106 Fan

    F106 Fan

    Oct 19, 2011

    Retired electrical engineer...

    The FCD isn't very popular on this forum. It is a solution to a problem that doesn't exist. I think everybody around here either uses a taper crimp die or a standard crimp die set so that it just barely closes the mouth. I prefer the taper crimp die because a modest amount of rotation doesn't make a radical change in crimp - the 'taper' part.

    If you look inside that Dillon seater die you will see how there are two choices: round nose and SWC depending on how the insert is rotated during assembly. Even then, the round end of the insert may not fit the bullet very well.

    You summed it up pretty well: nobody has tried your configuration and if you need data you'll have to get it yourself. Most of us just load and shoot, at least as far as pistol is concerned.

  19. fredj338


    Dec 22, 2004
    :rofl: You math guys.
    You are likely to get more uniform results seating & crimping in separate steps. If you want them perfect, stop using plated bullets & mixed brass & things will be close, but you'll never get perfect.:dunno:
    Last edited: Nov 19, 2011
  20. DanaT

    DanaT Pharaoh

    Have you perform a gauge R&R study on your measurements of OAL? Maybe the +/- 0.005" is all within you measurement error?

    Here is how I would look at it. If I were setting up a maching to make 100,000 cartridges a day, you bet I would worry about +/- 0.005 but then I would also monitor the trending of the OAL. I would know what my instrument is capable of measuring. I would know when the machine was starting to have too much variation.

    For a box of reloads to shoot up at the range. No. Not enough money involved to worry about it.