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Inconsistent OAL Variance for 9mm

Discussion in 'Reloading' started by GhettoSmack, Nov 18, 2011.


  1. GhettoSmack

    GhettoSmack
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    Here are the details:
    Dillon XL650 w/UniqueTek Toolhead Clamp Kit
    Station 1: Dillon Sizer/Deprimer die
    Station 2: Dillon powder die and powder dispenser
    Station 3: Empty
    Station 4: Redding Competition Micrometer seater die
    Station 5: Lee Carbide Factory Crimp/Full-length Sizer die

    I've been loading .45ACP on this press with the same die setup for almost a year with excellent results (OAL variance of +- .002"). Berry's 230gr Plated RN @ 1.260". (Montana Gold 230gr CMJ varied +- .005 due to ogive.)

    I started loading 9mm and OAL variance is +- .005. 124gr Berry's Plated RN. I've loaded ~500rnds.

    My dies are clean. Everything is tight. The rotating case retention plate is tight without binding. I'm using mixed already-fired range brass.

    So what's the deal?? Are my cases not clean enough? Is it case length difference? Is it just the bullet shape matched to the seating die shape?

    Thanks for your comments and experience.
     

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  2. Colorado4Wheel

    Colorado4Wheel
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    So are you saying you have it set for (for example) to 1.130 and it varies from 1.125 to 1.135

    Or

    You have it set to 1.130 and it varies from 1.128 to 1.133?
     

  3. fredj338

    fredj338
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    Even the worst case, a variation of 0.005" isn't hurting anything. You probably have a bad batch of Berry's bullets w/ more deviation in the nose shape than should be.
    Steve brings up a good point below. Mixed brass. Thre is a lot of variation in 9mm brass & that always affects OAL, especially w/ soft plated or lead bullets.
     
    #3 fredj338, Nov 18, 2011
    Last edited: Nov 18, 2011
  4. Colorado4Wheel

    Colorado4Wheel
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    Even some nicks on the base/rim of the brass will lead to more OAL variation. +/-.005" ain't a big deal. Just to make you feel worse, I get better then that with a stock toolhead, mixed brass and a Lee seating die.
    Might want to make sure you tighten the lock ring with the bullet/case combo in the die.
     
  5. mogollon

    mogollon
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    Most likely it is simply ogive variation from one bullet to the next. You can verify this by removing the seating stem from the seating die, place it over the nose of the bullet, and measure from the base of the bullet to the top of the seating stem. (mm is more prone to this than 45, simply due to the smaller diameter.
     
  6. rpgman

    rpgman
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    yep, I sort my brass, both 9mm and .40.
     
  7. F106 Fan

    F106 Fan
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    This can certainly be a problem. I am using both the Redding Competition and the Dillon seating dies and I have some variation as well. I am pretty convinced that the shape of the nose of the bullet isn't consistent.

    It might be interesting to see if the variation is different when you load Sierra Match bullets versus bulk jacketed or plated bullets. I wonder if I am getting anything for that 'match' designation. And, no, I am not loading match bullets at the moment.

    Richard
     
  8. GhettoSmack

    GhettoSmack
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    Clarification:
    I'm TRYING loading 9mm to 1.150. The loaded and crimped rounds come out from 1.145" to 1.155" . Variance of +- 0.005; total variance of 0.010.

    These are for competition (IDPA, USPSA). I am a little OCD so I like CONSISTENCY. My concern is that chrono-ing a round 1.155" will not meet [Minor] PF and 1.145" - 1.150" will be on the line. Practice rounds are one thing, but competition rounds I want THE SAME with no surprises. (Do I sound like a bullseye shooter? haha)
     
  9. GhettoSmack

    GhettoSmack
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    Thanks for your comments and suggestions. Sounds like bullet shape and case length might be the biggest culprits. I may have to experiment with different manufacturers to see which ones fit the seater die the best = most consistent. I just don't want to spend too much on FMJ compared to Plated.

    Then, again .... what's the harm in loading practice rounds (low cost, inconsistent length plated) and competition rounds (higher cost, consistent FMJ)? Nothing wrong there!
     
  10. F106 Fan

    F106 Fan
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    I would assume you are loading to 130 PF instead of trying to cut it really close. After all, the tests aren't going to be done with your barrel and there is no 'standardized' chronometer. You need some slack.

    So, load some short - say 1.140" and some long at 1.160" and see what difference it makes.

    My guess is that the difference will be much smaller than the difference between 40 deg F and 110 deg F. Heck, you may find that keeping the cartridges in your pocket results in 10 fps over letting them sit around in cold air. Always turn in the warm shells.

    Look at the standard deviation of your strings. Try to get a load that has minimal deviation. I have a load with Berry's 147 gr and 3.5 gr Bullseye with a standard deviation of 3.5 fps. The average is 906 fps and extreme spread is only 12.2 fps. The PF is 133.

    I used to race small hydroplanes with a 400# class minimum weight (boat plus driver and remaining fuel) which was measured AFTER the race. The trick was to jump out of the boat as you beached it to 'help' keep it from crashing into 'something'. And wear wool jogging clothes because you can pick up 10# of water before you get back in the boat.

    Everybody wants to push the limits!

    Richard
     
  11. ron59

    ron59
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    I know with my 147gr Montana Gold CMJ, my OAL was +/- .002"

    With the Bear Creek Molys (also 147gr) that I'm using now, it's more like +/- .005" (if not .007"). Fred mentions that soft plated or lead bullets can/will affect OAL, certainly seems true for me too.
     
  12. rpgman

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    even though I sort my brass for both 9mm and .40, I still get a +/- .005 on some.
     
  13. fredj338

    fredj338
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    If your loads are that close, then stop gaming & add a safety factor in. I doubt 10PF is going to make or break you in a match. a 0.010" OAL variation isn't going to change vel more than std deviation anyway.:dunno:
     
    #13 fredj338, Nov 18, 2011
    Last edited: Nov 18, 2011
  14. GhettoSmack

    GhettoSmack
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    fredj338 - I guess you're right. 0.010 variance shouldn't affect PF that much. It's just frustrating to have to measure all finished rounds and separate.

    0.010 variance OAL works fine in my "plastic fantastic" guns and CZ85. My 9mm 1911 is much more picky. It loves S&B @ 1.155" AOL, but doesn't care much for -common reloading retailer- at 1.150. So I load for my 1911 and it works in all my others.

    From the current posts, it appears I am not the only one with the variance issue.
     
  15. rpgman

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    I'm sure we all have a variance issue. I measure only every 5th case.
    If it's within the +/- .005 of my OAL of 1.130 for my 9mm and .40 I'm fine with that.
     
  16. ron59

    ron59
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    Instead of having a concern, you should actually TEST this situation.

    You have a chrony, don't you? shoot 15 of them. 5 that are 1.155" and 5 each at the short/long versions. I bet you don't get more than about 15-20fps difference out of them, which isn't much. I target my load at 133PF or so with my 9mm, I want a comfortable cushion.
     
  17. GhettoSmack

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    Actually, I do not have a chronograph. No one I know -- many reloading competition shooters -- has one, either. At least not one they will let me use. I wish I COULD test the loads at different lengths. That's why I asked YOU GUYS ... the ones with a chrono and experience.

    From what I gather, if 0.010" OAL variance equals ~10PF, then loading rounds to 130PF at the short length (1.145") will be at ~120PF at the long length (1.155"). That's a DQ in competition (min 125PF). To cover that variance, I would need to load to 135PF.

    I'm not saying that is good or bad.

    So I will experiment with different bullet manufacturers to see which shape is more consistent in my press (seater die). Although .... I might try TWO seater dies (have an empty stage in my XL650). The first die to seat the bullet about 0.010 longer than desired. Then the 2nd seater die as the "finish" length. Anyone ever try this?
     
  18. Boxerglocker

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    You are worrying over nothing.... 0.005 +/- with you set up isn't gonna have any drastic variance in PF. I have almost the exact same set-up (plus shell plate bearing kit) use 135g Bear Creek molys, mixed brass with WST 1.150 inch OAL target. Usually at 0.005 +/- my loads have officially chronoed at state matches consistently. Last State IDPA 1024, 1024 and 1019 fps. (It was noted by all the official chrono was generous by about 20 fps. on my chrono consistent at 1000 fps, my target PF is 135.)
     
    #18 Boxerglocker, Nov 19, 2011
    Last edited: Nov 19, 2011
  19. BuckyP

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    In USPSA they chrono through your gun / barrel.

    This. I also agree going a little over 130, my goal PF is 132-133. That should give you a bit a leeway, and you won't even notice an extra 2 to 3 PF
     
  20. Colorado4Wheel

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    No wonder you are so freaked out. That is wrong in a huge way. No way a .01 change makes a 10pf difference at that oal. Maybe a 1-2 pf difference. IDPA'ers like to take their game a little too seriously sometimes. Stop worrying about it. Have fun. Don't waste your money on anothet seating die.