Weigh each powder drop?

Discussion in '6mm, 6.5mm, and .25 Cal (Not 6BR)' started by Stosh123, Jan 12, 2020.

  1. Stosh123

    Stosh123

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    Old timer wonders do most reloaders actually scale weigh the powder for each round or is the Harrel dispenser accurate enough for BENCHREST competition?
     
  2. JamesnTN

    JamesnTN Silver $$ Contributor

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    I weigh every drop on a lab grade scale to +/- 1 kernel to my desired load
     
  3. Stingray

    Stingray Gold $$ Contributor

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    same here
     
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  4. dstoenner

    dstoenner

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    Yes. Even 8208 because every now and then even it is wrong. For 100 general purpose shooting i load to +0/-.1 gn for my f-open loads i load to +/- .02 gn

    david
     
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  5. BoydAllen

    BoydAllen

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    It depends on the coarseness of the powder. I can throw to +- .1 gr. or better with ball powders and very fine stick powders like the LT powders, and 8208 and Benchmark. 133 is marginal. For anything coarser, I throw light and weigh. I could not tell you how many current 100 & 200 yd. benchrest records have been shot with thrown charges. Having said all of that, most shooters have no idea as to how to get the most out of their powder measure, and for them a Chargemaster is the answer. Obviously, for the cutting edge at 1,000 yds, for competition benchrest, higher standards are the rule.
     
  6. dgeesaman

    dgeesaman Gold $$ Contributor

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    Short range or 1000y?

    David
     
  7. Stosh123

    Stosh123

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    David, I only shoot 100 and 200 yds. I’m the guy that has been dilly dallying around with 100 new Lapua .220 Russian brass that DJ Brass turned the necks for me. Then before I loaded a single round, I found that running them through a Wilson resizing die, the cases came out scratched. Wilson polished the I.D. and that solved the problem. Finally got 50 ready for the range, just got to get a day here in South Carolina where it isn’t raining.
    After this 1st firing, is there anything I should do before the 2nd firing?
    Thanks to all that have taken time to respond. Stan




     
  8. jimmymac

    jimmymac Gold $$ Contributor

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    Dropped charges, three different loads of H322 using a Harrell’s BR thrower. 100 yard results.

    CC376199-7EB9-4AA6-9441-BB6AA0377AB4.jpeg

    I’m not saying it’s better. I am saying it works with acceptable results on the target if you have confidence in your throwing ability.
     
  9. johara1

    johara1

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    You will save a lot of components at long range throwing powder. Because you will be going home very early...... jim
     
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  10. jimmymac

    jimmymac Gold $$ Contributor

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    Jim, he's talking short range...
     
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  11. dgeesaman

    dgeesaman Gold $$ Contributor

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    There are a few short range benchresters at my local club. About half throw (using a high grade thrower such as a Harrels) and about half use a Chargemaster.

    Before you get too excited about Chargemasters, remember that they are accurate to within 0.1 gr in most situations. Throwers are maybe twice that. i have to wonder how many HOF points have been earned using either method - because both are competitive.

    It can be argued that it's easier to keep in tune with more consistent charge weights. So to that end I understand the choice of a Chargemaster.

    Weighing to the kernel is 5x to 10x finer than 0.1 grains. For short range I truly don't think that will ever matter. Leave that to the 1000y competitors.
     
  12. Stosh123

    Stosh123

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    All is very interesting.
    Jimmy Mac: I can only hope to get groups like that. Then again, maybe the new brass will surprise these 82 year old eyes. Having 1500 rounds using my original 100 pcs of Lapua brass, might have something to do with the less than stellar groups.
     
  13. johara1

    johara1

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    He said bench rest, I guess 600 and 1000 don't qualify? I do know as I said before short range loading is crude to what you need for long range, I weigh to the +-.01...... jim
     
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  14. Hohn

    Hohn

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    The Pareto principle is especially useful to shooters, and it is easy to control powder charge variation sufficiently to have to face much more difficult source of variation.

    In engineering, we refer to the "stack up"-- the combined effect of all sources of variation. And we target first the ones that are easiest to control to move them far to the right in a Pareto. The idea is you first go after the most relevant factor, reduce it to irrelevance, then move on to the 2nd most important factor, etc, and repeat the process.

    The critical question is: How controlled must be my charge weight variation to rule it out as a meaningful source of variation?

    I've yet to see any data that is conclusive that accuracy of charge weights better than 95% +/- 0.1gr produce a measurable improvement in groups. Anecdotes aplenty, but no actual data that would support a valid statistical conclusion. The standard error of a 3, 5, or even 10 shot sample is much too large to allow such conclusions. Shooting the sufficient sample size would burn out your barrel in most instances.

    If you are shooting a 36gr charge weight and arguing that you need better than 0.1gr, you are essentially asserting that controlling charge weight to 95% within 1/360th of the total amount is inadequate--or that you can observe a difference between two charges that are 1/360th the total amount apart. That's a pretty bold claim. And more importantly, it requires INCREDIBLY large samples, controlled conditions, and exhaustive testing to prove or disprove. The bigger the case and heavier the charge, the less it matters how precisely you control your powder weight.

    For the 40gr neighborhood of charges I use in my favorite loads, even 95% +/-0.2gr is more than adequate for ruling out powder charge weight variation as a meaningful source of variation. This is a total variation that puts 95% of my charges within 1% of the nominal mean. That is adequate in almost every instance, and until and unless you have controlled your OTHER sources of variation there's little value in pursuing more precise charging.


    Once you've controlled your charge weights to within 1% of the nominal value, work to get your neck tension and case capacities within 1% as well. (hint: they aren't). CBTO is pretty easy to control well. But neck tension? You need to be turning necks and annealing every time to get CLOSE to keeping neck tension within 1%. Variation in hardness alone will produce well over 1% neck tension variation even with turned neck of identical geometry. Are you using a precision reamer on your case necks? If not, how can you hope to keep your neck tension within 1%?

    Charge weight matters a lot, but it's also very easy to check the box on that front and move on to the items that are much more difficult to control anywhere near a comparable level of precision.
     
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  15. johara1

    johara1

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    you may want to weigh primers and trim and point bullets and you will get closer..... and weigh powder to the .01 +-.... .001 nt. and necks turned to the same .0001 and of course annealing and ES in the low single digits..... jim
     
  16. CharlieNC

    CharlieNC

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    At the distance you intend to shoot, especially further than 100yd, do a ladder test using fine increments at that distance and you will see for yourself how much it matters. Load +/- 0.1 and 0.2 and measure the vert and horz changes in POI. The further you go, the more impact you will see unless you have already used this type of approach to identify your node.
     
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  17. jimmymac

    jimmymac Gold $$ Contributor

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    Look at post #7. Short range.
     
  18. johara1

    johara1

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    Post #1 says Benchrest in bold caps..... lol.... jim
     
  19. Iowa Fox

    Iowa Fox Silver $$ Contributor

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    82! That's good news, that means I might have 10 more years left.
     
  20. BoydAllen

    BoydAllen

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    One of the advantages of shooting benchrest for some time is that you end up with fire forming barrels. Using one that is not totally trashed, you can simply load cases as perfectly as possible with regard to powder charge weight and uniformity of CBTO and then shoot them over a chronograph, sorting according to velocity to make groups of cases that produced velocities that have the least spread. Bart Sauter shared this in a post and I really think that he is onto something. I added the part about the fire forming barrel because I assume that he does not use the one that he has set aside for the nationals for this sort of work.
     

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