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Powder Metering Uniformity

Discussion in 'Shooting Related Threads' started by EdSy, Jun 23, 2013.

  1. EdSy

    EdSy Active Member

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    I've been struggling today to load a few hundred 12 ga. trap loads on my old MEC 600 JR. My specific problem is powder metering uniformity when loading 700X powder. I use the current style MEC shot/powder bars, with interchangeable powder bushings. I understand that simply running the bar back and forth with just the powder bottle mounted will not result in the same powder drops as when processing shells. So, I tried depriming, seating primer, dropping powder and then pouring the powder (being careful to get it all) into my RCBS electronic scale pan. After noting the powder weght and correcting the worst offenders, I returned the powder to the primed hull, seated the wad, dropped the shot and crimped. I repeated this over and over until I had established that my powder weight total range was about a half-grain (i.e. +/- 0.25 gr.)or maybe a little more. Is this normal for 700X? What powder would give me better (hopefully "best") uniformity of weight drops? Many Thanks, Ed
     
  2. EdSy

    EdSy Active Member

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    The press is solidly mounted to my bench, and the bench is a solid one. The most significant variation, shell to shell, is the de-prime/resize step. I can try reducing that variation, and the primer seat by running 25 hulls through the first two stations as a batch, before the powder drop / wad seating operations. Then, I'll try powder drop - precrimp - crimp as a set on individual shells, and also separating the powder drop / wad seat from the crimping steps.

    But, would changing to a different powder help with powder weight uniformity? What powder(s) give the most uniform weight drop? Thanks again, Ed
     
  3. Star4Ever

    Star4Ever Member

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    The reason I have a firmly mounted hydraulic MEC 9000 is to best achieve consistent powder drops. The hydraulic system does everything the same, time after time thus reducing variances.

    However, 700X is a powder that sometimes meters with higher variances. You may want to cut a long strip of fabric softener sheet (the kind used in the clothes dryer). Tape this to the mouth of your powder bottle so that the strip falls into the powder bottle but does NOT obscure the mouth of the bottle. It will reduce all sorts of static and allow the powder to flow very smoothly. This will result in better and consistent drops.

    With a manual system such as yours, you need to pay attention to the cadence and force and speed of the lever action of the press. Variances in you arm movement and speed can indeed cause inconsistent powder drops.

    Remember the bushing are volumetric.... the grains are weight. There will always be some variance depending upon how the kernels and donuts of powder stack up in the bushing. Chaos theory at its best.

    Art
     
  4. 9point3

    9point3 Well-Known Member

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    One can not measure true volumetric uniformity with a scale just as one can not prove the accuracy of a scale via the graduated cylinder.
     
  5. EdSy

    EdSy Active Member

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    Fortunately, I am not worried about volumetric uniformity; only the actual weight of the powder dropped into my empty hulls.

    Can anyone suggest a powder for 1 oz - 1-1/8 oz trap loads that meters more uniformely?

    Thanks, Ed
     
  6. Zoom.Golly

    Zoom.Golly Well-Known Member

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    +-.25 grains is plenty okay, and probably a bit better than many (most?) get with 700x or any big flake powders, e.g. Red Dot, Green Dot, Promo, especially with a single stage loader. I don't believe claims that some make about +-0.1 with those powders. Red PC baffle isn't much of a help with those powders.

    Reloading is easier than many want to make it, but if you really need to reduce the variance go to another powder. PB worked the best of the powders I have used, but it's unaffordable. International Clays was good, Clays almost as good. Clay Dot seems good, but I don't worry about drop variance anymore so I haven't really checked carefully.

    I have some 20, 28, and 410 gauge powders that are excellent, but they are not much help for those looking to load 12 gauge.

    Good luck.
     
  7. Lovemy99

    Lovemy99 Member

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    Try Titegroup. Smaller grains seem to drop the most uniformly through my MEC.
     
  8. Bob Merkov

    Bob Merkov Member

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    Ed,

    I find Clay-Dot to measure pretty consistently. I do get a fluctuation (as with any powder) when the humidity rises. I notice a variance of 1/10 of a grain, sometimes 2/10, but I don't let it bother me. Like Sam.Brown says, don't worry about it.

    Bob M.
     
  9. Leo

    Leo Well-Known Member

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    I have both MEC juniors and MEC progressives. With your junior, remember the number 5. While you are loading, the powder gets jostled 5 times before it goes in a hull. With a progressive, it only gets jostled once. The same number bushing in a progressives throws a lighter charge than in a junior. The lighter the powder flakes, the more difference the 5 handle strokes make. When selecting a bushing, full stroke the handle 5 times, letting it "clunk" on the top and bottom of that stroke. Now throw the charge and weigh it, that is what your hulls are getting. Keeping the powder bottle at least 1/2 full keeps things consistent also.

    Good Luck
     
  10. Shooting Coach

    Shooting Coach Well-Known Member

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    Are you cycling the press the same number of times checking powder as when loading shells?

    Single stage presses tend to pack powder into the bushings more uniformly than progressives.
     
  11. Johnny

    Johnny Well-Known Member

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    + or - .2 is about all you can really expect. Every one wants to believe their press it dropping within .1gr but that is not very realistic.

    I wouldn't worry about .5 grain variation as long as you aren't loading max loads. You won't know the difference.
     
  12. mike campbell

    mike campbell Active Member

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    I dump my powder out on a sheet of plywood and pick out all the square flakes.
     
  13. Brady509

    Brady509 Well-Known Member

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    PB and 7625 meter great for me regardless. I use the cheap powder baffle and can load in a earthquake with second to no variance.

    Brady
     
  14. EdSy

    EdSy Active Member

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    Thanks to all who responded. -Ed
     
  15. uplate

    uplate TS Member

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    I used to use 700X in handgun loads but no longer do and one of the reasons
    was the variation of charge weight in small amounts metered for handgun. In
    general, fine grained powders meter more uniformly, especially ball powders.
    Titewad would be a good powder for you to try as it is close to 700X in burn
    rate. It is so fine grained that it may leak from your loader without a washer
    under the powder bttle. Bullseye is fine grained and consistant if you are
    just loading one oz loads. It is a bit too fast for 1&1/8 oz.
     
  16. shotgunner50

    shotgunner50 Member

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    Ed,
    I have loaded a lot of 7oox over the years and the last 2 containers a 4# and a 8# would not weigh consistently.I don`t believe it is anything you are doing wrong it is the powder.I can load clays and be very consistent with my 9000 or 650.
    M Taylor shotgunner 50
     
  17. JT 27

    JT 27 Member

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    Powder baffle, ground the loader, use anti cling strips, consistent cycle the press, hydraulic assist if you can afford it.
     
  18. Gregg535

    Gregg535 Member

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    Jan 29, 1998
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    That is a typical amount of variance for 700X or Red Dot and is fine. No problem. If you really want a powder that throws an accurate weight try Ramshot Competition powder. It is a ball powder and flows at a concistent rate whether the bottlle is full or half full, etc. The burning rate is similar to Red Dot or 700X.
     
  19. Ajax

    Ajax Well-Known Member

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    If you have ever chronographed new shells. 65 to 80 feet variance. You would not be to concerned about a small difference in powder.

    Ajax
     
  20. ImpalaBob

    ImpalaBob Member

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    You might be very suprised at the powder differences in factory shells.

    Getting a pretty good average within my min-max range is about all I care about. YES I use a powder baffle under the bottle .... and have no static issues with my loader.
     
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