Same volume of powder, different weight?

Discussion in 'Reloading' started by Oliveralan, Oct 27, 2009.

  1. Oliveralan

    Oliveralan Well-Known Member

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    Hello,

    I just bought a lee powder measure kit, because I have read several times that some of the most accurate loads are made using volume measures. When I weigh the volume-measured charges I get different weights all the time, with the lee dippers it varies by up to 1.5grains... Using the case activated powder measure on my hornady lock n load ap press the charges still vary by .1 grains. Is this acceptable? I will do accuracy testing next weekend to see how accuracy is. is it normal for weight to vary like this? What can I do to get more uniformity?

    Thanks,
    Oliver Lottermann
     
  2. Winchester 69

    Winchester 69 Well-Known Member

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    Variation of weighed volumes should be due to humidity. When you use several means to measure by volume and the inconsistencies are not uniform, you are dealing with co-variation. i.e., there is more than one source of variation. Your Hornady LnL measure's consistency simply brings to light the high variation in the other measured volumes.

    If by Lee powder measure kit you are referring to the boxed set of dippers, what you have learned is that the form of measurement has high variation; this may be reduced with practice. The dippers are effective in conjunction with the use of a trickler for weighing the charges.
     
    Last edited: Oct 27, 2009

  3. Mikecr

    Mikecr Well-Known Member

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    I think you will only know by shooting over a chronograph.

    I wonder which would provide lowest ES: The exact same number of powder granules, or the exact same weight?
    And does moisture affect granule volume in a way that counters weight change? That is, if 235 dry granules fit a given volume, would they fit the same wet?

    It's an interesting topic. Maybe I'll count out a pet load & fiddle around with this..
     
  4. Johnboy

    Johnboy Well-Known Member

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    if you are useing the little dippers,this is what I do.use the chart and find the dipper needed for the charge.then I trickel the rest in.if one was only loading to just plink I wold just dip and charge a case.but I would scrape off the top of the dipper with a knife edge.but you are looking for accuracy and not to just plink.and for me most of the time I don't really worry about .1 grain.maybe I should but it hasn't messed with accuracy from what I can tell.
    do you have a trickler? if not I may be able to get you one.I really don't use mine that much anymore.I just add with a dipper really slow to get the charge I am looking for.just let me know if you need it.
    John
     
  5. Oliveralan

    Oliveralan Well-Known Member

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    John,

    I do have a powder trickler, and this is what I did to load my rounds for my ladder testing but I'm curious as to what gives better consistency, the same volume of powder or weight. Mikecr asked the exact question I wasn't able to formulate properly. What gives the least spread in velocity? The same weight or the same volume? If you can't have both. I have loaded 30 by volume at are at an average weight of 41.5grains each and I will load another 30 by weight of 41.5grains and see the average group sizes. The measure on my press is looking good since weight varies by no more than .1 grain and volume is the same charge to charge. Interesting stuff.. If anyone has done chronograph tests or knows someone who has please post the info or a link.

    Thanks,
    Oliver
     
  6. Johnboy

    Johnboy Well-Known Member

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    :) I think that I'll put my money on weight.:D this is whatworks for me.lightbulbbut I think you have a good idea on things.keep it up and you will be shooting with the best.
    John
     
  7. MagnumManiac

    MagnumManiac Well-Known Member

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    Winchester69 has it right!
    Even if you weigh your powder precisely on one day, on another day it MAY be different due to humidity changes.
    Whether it's weighed or measured, a .1gr+/- is not going to show any significant change in velocity, but due to the same humidity change, it may show a significant vertical dispersion on target due to changes in combustion.
    This is a little known fact by many loaders, that's why in benchrest they tune their loads on the day, not the week before!
    I always use the same setting on my measure, whether it corresponds with the initial weight setting or not! I have had differing weights of 1.5gr's on any given day, and it doesn't seem to affect accuracy or velocity a great deal. Rarely does this pose a problem once a 'node' is found, a good 'node' will run 1gr+/- without affecting anything drastically.
    :D
     
  8. Fitch

    Fitch Well-Known Member

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    Plus or minus a full grain makes no difference? As a general statement I respectfully disagree. That's a pretty big charge variation. I've never seen a "node" that was 2 grains wide with no POI variation.

    I have seen group sizes that didn't change significantly for that much variation when doing ladder testing, but POI certainly does, and POI is what kills game.

    That might apply if you are running 100g loads, or shooting at short range. But if you are running 20g loads the ES will be awful loading +/- 1 grain. +/- 1g is 110 fps in my .30-06 (my normal ES is 10 to 20 fps). It would be 512 fps in my .22 Hornet, and that "definitely" matters in the Hornet. In the .30-06 it's 3/4" at 300 yards. The Hornet would be all over the place at 150 yards.

    YMMV

    Fitch
     
  9. boomtube

    boomtube Well-Known Member

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    "I have read several times that some of the most accurate loads are made using volume measures. "

    I suspect you have been reading "bench rest" type articles.

    Those guys frequently use fine grained powders and very high grade dispensers so "some" of the time weighing doesn't matter to them, but they don't use Lee dippers either. At the ranges they shoot, 100 and 200 yards, a few tenths variation rarely matters but few of the rest of us accept that.

    Few of use would ever see any difference in a charge spread of .3-.4 grains at ranges under perhaps 300 yards. BUT, our powders are frequently much too coarse to be that consistant with simply dropping the charges so we usually weigh them.
     
  10. Mikecr

    Mikecr Well-Known Member

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    It also seems like the questions/answers may need qualification..
    The answers may be different for those who load at the range -vs- those who load in the garage -vs- those who load in an air conditioned reloading room. Same with those loading purpose-built 6ppc or 30brs -vs- the rest of the world.

    For example, I load in the house(in my wifecannotenter room). So I highly doubt variance in moisture comes into play one way or another for me(I weigh). My guns are purpose built only to decapitate woodchucks at abstract ranges carried.

    But I'm curious, like thread starter.
     
    Last edited: Oct 28, 2009
  11. MagnumManiac

    MagnumManiac Well-Known Member

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    You have mistaken the point I was making!
    I wasn't stating that a +/-1gr variation was present in the loads being used.

    I was stating that if your intended load was, say 81gr, and your measure on the day was giving you 80gr, as weighed, then it would pose no major problem, as long as the volume was identical.
    Group sizes would be no different, as combustion would take place just as it did when the powder weighed 81gr, as measured.

    My point is this:
    A good node will give you a 'window' where your bullet will exit the muzzle at a point that is constant and it may have an acceptable 'window' that is +/- 1gr of your intended load, not to be confused with a varying set of loads that vary by this amount!
    :D
     
  12. Winchester 69

    Winchester 69 Well-Known Member

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    Excellent commentary, sir. Exactly the point to be made.
     
  13. Fitch

    Fitch Well-Known Member

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    You are correct! I was mistaking the point you were making. I hadn't thought about it the way you intended. Now I need to think about your real point.

    Fitch
     
  14. Oliveralan

    Oliveralan Well-Known Member

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    Interesting point fitch, misunderstood it at first aswell. But I reload in my house with aircon so humidy is uniform. The problem I'm having is that when I measure one lee dipper of powder, weight it, then measure another, I get a weight that may be off by a grain or two. I fill the dipper then scrape the excess off with a paper business card. Why are my weights for an equal volume so off? I'm loading for .308win so +/-1grain out of 41.5 is quite a bit.

    Oliver