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Powder Volume vs. Weight

Discussion in 'Shooting Related Threads' started by Crickets, Jan 8, 2012.

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  1. Crickets

    Crickets Member

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    Curious. I started a new 8# jug of Red Dot in my mec today. There was about a 5th of a bottle (short mec bottle)left of old powder left since summer, and I filled the rest of the bottle with new powder. I cycled the machine a few times (dropped powder and shot) and after calibrating my scale weighed 3 charges of powder - 17.6, 17.7, 17.6. Well within my expectations and the same its been dropping for a year. I ran 50 shells and as usual weighed a sample - 18.8, 18.9, 18.7. !!!??????. Well within the specs of acceptable loads, but now nearing 1250 fps rather than 1180. But it got me wondering 1st - Why would there be such a large difference between lots of powder - Especially Red Dot - you'd think there wouldn't be that big a difference. AND 2nd, people have stated that humidity can cause big differences in throw weight, so I'm wondering how humidity would change the actual powder charge. Lets say we have 17 (for a 1145 fps load) grains of powder that was absolutely dry, and you added 1 grain of moister to that for a 18 grain measured weight - wouldn't you still have a 1145 fps load?
     
  2. Oscar Ray

    Oscar Ray TS Member

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    When you change powder lots, you need to check how much you are throwing. I am not sure why, but powder from lot to lot can have different densities.

    Oscar
     
  3. skeeljc

    skeeljc Supporting Vendor Supporting Vendor

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    The best way to regulate a load is to load five shells and chronograph them. This is the only way to be sure that you have the right powder charge. This is how the shell manufacturers do it (they also measure the pressure).

    Jim Skeel
     
  4. Ahab

    Ahab Well-Known Member

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    When you get a new jug of powder ... shake it up!

    It may have been sitting on a shelf for a long time and settled within itself.

    I do the same thing if I haven't loaded for a week.

    Let us know how it measures out after you fluff it up a bit!
     
  5. AEP

    AEP Member

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    Just spit-balling here, but when I was testing and weighing loads I found I would get a heavier weight with the same volume on rainy days when the hummidity was up. I haven't done enough checking to verify this it was just something I noticed.

    The velocity, chronographed, seemed to be the same.

    Just a thought,

    Andy
     
  6. shot410ga

    shot410ga Well-Known Member

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    AEP is right on...
     
  7. APrice

    APrice Active Member

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    "The best way to regulate a load is to load five shells and chronograph them. This is the only way to be sure that you have the right powder charge."

    Sorry, I'm not buying this theory. Not even practical for most of us. The BEST and MOST PRACTICAL way to produce consistent loads is to accurately weigh the powder charge.
     
  8. skeeljc

    skeeljc Supporting Vendor Supporting Vendor

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    I agree the "practical" way to check is to weigh the powder charge. Everyone has a scale (although some do not understand "how" to take representative samples).

    I am just not sure that weight is the best method to determine the correct powder charge. It is great for checking consistency. What we are really after is the desired speed. If you want a 1180 fps shell 1250 fps will make you think about finding a different powder.

    I just use the same bushing and check velocity when I get a new jug of powder. The shell velocity is what is important to me.

    Jim Skeel
     
  9. APrice

    APrice Active Member

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    "The shell velocity is what is important to me."

    Velocity (actually SHOT velocity) and pressure is what is important to all of us, but for those without elaborate testing equipment there is all that testing done by the powder manufacturers to consider. We have to assume that the chart values for a particular weight of powder are accurate. If we cannot make that assumption, very few of us should be reloading.
     
  10. Crickets

    Crickets Member

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    Aprice is on to exactly what I am wondering. Same powder - 1 gr difference. I dropped the Volume down to accommodate the published weight. Pretty large amount really. If its a moisture content thing I have just dropped my velocity by 100fps from what I loaded last assuming a lower volume charge to make the lower weight. I do not have all the great equipment - all I have are my "spidee senses" when I shoot indicating that I have a load I like. If there is a change in density from lot to lot or dry day to wet day, then it would mean you'd have to chrono your shells every time you get a new jug or you have a wet day. Is Aliant packing in 5% more power into every flake of red dot? Seems to me I should leave the Volume setting that has been performing so well for me and not worry about the weight - Right? or am I way off?

    By the way I do shake up the jug before pouring it into my bottle, plus the pouring process itself should loosen up the powder and I have a baffle that has been pretty reliable for the past year. - About 2000 rounds reloaded
     
  11. skeeljc

    skeeljc Supporting Vendor Supporting Vendor

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    Crickets and I think alike. Once I have a bushing that drops the charge that I want I tend to keep using that bushing. I am a little reluctant to change my bushing when the charge weight changes. That is why I like to use a chronograph.

    I wonder what Hodgdon would say about a 1 grain difference between two jugs of powder?

    I also have my doubts that relative humidity can affect powder drops if it is stored in the original container.

    Jim Skeel
     
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