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I Never had this problem reloading before ?

Discussion in 'Uncategorized Threads' started by ZeroHero, Jan 25, 2008.

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  1. ZeroHero

    ZeroHero TS Member

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    I ran into a new problem the other day that never happened before. At least never that I caught it anyway. I opened a new can of PB powder and set up the loader. I normally weigh about 4 shells out of every 100 after I get things going. Everything went normal and I loaded 400 rounds. When I came back to load another 200 a couple of days later the charge weight of powder was 1/2 grain less then it was on the first loading session.

    I did everything just as I have in the past and never had this happen. Anyone have any idea's or suggestions of what might have happened?

    Duke
     
  2. hmb

    hmb Well-Known Member

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    It's not a problem. HMB
     
  3. zzt

    zzt Well-Known Member

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    Changes in humidity can make that happen. 1/2 grain is near the max that can be caused by humidity, but I wouldn't worry about it. You really are loading by volume, not weight. So if humidity adds .2 grains to what your normal bushing throws as weight, nothing that counts has changed. The shells will perform identically.

    BTW, in case you are interested, different lots of powder can require a greater change than 1/2 grain. When I open a new lot, I load up some according to my favorite recipe, then go out and chronograph them. If they are much low or high, I use smaller or larger bushings to compensate. When I have it "right" (as in, in the ballpark), I use that bushing for the rest of the jug/lot.
     
  4. Capt. Morgan

    Capt. Morgan TS Member

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    I deal with this continuously on my PW. Same bushing, same powder lot...one day it drops 17.2 and the next day it drops 16.8. I've stopped worrying about it since we're dropping powder by volume anyway.

    Morgan
     
  5. ZeroHero

    ZeroHero TS Member

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    Thank you for the replies. This was a new can, and I had to go down 3 bushings to get the weight that I was loading from the old can. I guess the part that puzzles me is which weight would be the correct one by the book? (powder with more/less humidity) I tried again this morning and I had to go 1 bushing larger to get back to the original weight. I only load published loads and I check the weight each time I load. If you lived where it is very humid does this change your loading data?

    Duke
     
  6. zzt

    zzt Well-Known Member

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    Duke, it is possible your old can of PB was manufactured in the USA. The new stuff has been manufactured in Canada for some time. It is finer grained than the old stuff, and does requires different bushings to throw the same weight.

    Regarding your question about what is the correct weight vs. humidity level, I don't know. I can tell you that over the course of using an entire 8 lb jug of e3, the bushing I use will throw 15.9 grains about 90% of the time. If we have a particularly humid spell, the volume is the same, but the weight might go up. The problem is worst in the winter, because we have extreme humidity swings. In the summer, our air conditioning has a relative humidity compensation, which we enable. It keeps the relative humidity at 45%. Consequently, the weights thrown by my bushings are very consistent in the summer.
     
  7. Tim Lee

    Tim Lee Member

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    Duke -

    I've seen similar variances from one day to another out of my PW800 and also have correlated it to humidity, however I've only noticed it with Solo 1000. Although I did use PB for a short time, I never noticed it varying more than a couple tenths or so... I THINK that is because during that short time period of my using PB, there wasn't a great deal of humidity change from one loading session to the next.

    my .02,

    -Tim
     
  8. phirel

    phirel TS Member

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    I have a few problems with some of the above answers. It is true that we drop powder by volume and not weight. But the performance of the powder is by weight, not volume. Equal weights of powder charges should preform uniformly but equal volumes of powder may not preform the same if the weights are different.

    Powder is only slightly hygroscopic so the relative humidity in the air surrounding the powder should have very little effect on the weight of the powder.

    I do agree that 1/2 gr difference in powder charges is not going to have a major affect on performance but it is probably the maximum acceptable variance.

    Powder packing in the powder hopper will cause variance in the drop charges. I do not know if this could result in a 1/2 gr difference.

    Pat Ireland
     
  9. Hauxfan

    Hauxfan Well-Known Member

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    Porch Dog, When you open a new can of powder, it is always a good idea to check your loads and see if it meter's the same as your old lot.

    Some powders, and I'm not saying it is your powder, but some powders vary from keg to keg.

    Better to be safe than sorry.....

    Hauxfan!
     
  10. Tim Lee

    Tim Lee Member

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    Pat -

    Is it possible that some powders are more hygroscopic/prone to weight changes due to humidity than others? Particularly in Pistol Cartridge Silhouette loading, I use some pretty small quantities of powder in some calibers and really keep an eye on weight as even a couple tenths will make a noticeable difference in FPS and pressure indicators (primarily 22 Hornet and .32 Mag). While I've attempted to take the powder packing variable out by using baffles in all my powder measures, I do seem to show some powders varying more than others.

    -Tim
     
  11. hmb

    hmb Well-Known Member

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    Oh, I forgot, shake well before using. HMB
     
  12. waverider

    waverider Well-Known Member

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    I am with Pat Ireland and will add that the recipes are in grains not volume.

    I also agree that even 1/2 grain will not mean much, unless you are loading a recipe close the maximum pressure of 11,500 psi for a 12 ga and the drops are become higher.

    I feel that what is more important is the consistancy of the powder drop for each bunch of shells loaded.

    Jason
     
  13. zzt

    zzt Well-Known Member

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    Pat, to make this simple, assume the powder absorbs absolutely no moisture. Water vapor condenses on any solid, even at room temperature. In some conditions, more, in others less.

    So my bushing that throws 15.9gr of e3 at 72 degrees and 45% relative humidity delivers x weight of powder and y weight of water. Change the humidity levels greatly and the same bushing, which is measuring by volume, throws the same volume of powder, thus the same weight. More or less moisture is included in the sample, and that is why the weight varies.
     
  14. Bocephas

    Bocephas Well-Known Member

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    Porch Dog, I have had the same thing happen to me.
    I think I put a post on here last year just like yours.
    Now on when I open a new bottle of PB I check the load quite often.
    Once you get it adjusted you will have no problems.

    Bo
     
  15. mercedesman1981

    mercedesman1981 TS Member

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    Just a thought here,

    We might be able to guess when we need to pay attention to our powder weights when there is enough static electricity to cause the powder to stick to the outside of the bottles.

    My MEC has plastic bottles and with the weather cold and clear for the past several days in Seattle, the static electricity is more note worthy. It is quite dry here now, humidity must be close to 20%.

    Just a thought,

    Mike
     
  16. phirel

    phirel TS Member

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    zzt- You missed a critical point in your post. Water (humidity) will condense on any surface only after the relative humidity reaches at least 100%. Assuming everything in the reloading room is at the same temperature, if water would condense on the powder, it would also form dew on everything else in the reloading room.

    If your reloading room was warm, and your powder very cold, condensation could occur but few of us keep powder in the freezer.

    Pat Ireland
     
  17. BuckGuru

    BuckGuru Member

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    If you fill up your powder hopper, then give it a few taps on the side with a screwdriver or other object, you will be amazed at how much the level in the hopper drops. I believe packing the powder like that, or leaving it loose, is more likely to be causing your variations than humidity. You keep the powder in a closed container and then put it in a hopper and close that up, so I can't believe humidity changes it that much.

    BTW, if you have a MEC and want to keep the charge weights the same for every session, get an adjustable charge bar. Just dial in the correct weight at the beginning of each session, and check it frequently as the powder level in the hopper changes.
     
  18. skeeljc

    skeeljc Supporting Vendor Supporting Vendor

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    I am not sure that powder performance is proportional to weight. The surface area to the powder flakes is probably a better correlation to energy released. That would mean that volume is a better coltrol. Can you imagine the powder companies specifying a 0.148617 cubic inch volume as the recipe? Factory shells are loaded by volume, not weight. I beleive load data specifies weight because that is what reloaders can measure.

    Once you develop a good load just stay with the same bushing and you will be good.

    Jim Skeel
     
  19. 22hornet

    22hornet Well-Known Member

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    PerazziBigBore;

    That is true! I've done it, too. Gene Hill once wrote an article about finding the perfect dove load. What he did was carefully arrange a bunch of shells..7½'s, 8's, 3 dram, 2.75 dram, etc. into seperate groups. He then dumped them all together into his pouch and went dove hunting! He said that he had one of his best days afield...
     
  20. zzt

    zzt Well-Known Member

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    That is not strictly true Pat. Whenever water, in the form of water vapor, is present in air, liquid water exists as well. It is found on everything in contact with the humid air. The liquid and gaseous phases are in equilibrium. There is continual exchange between the phases, that is, water vapor condenses and water evaporates, even at a relative humidity of 45%. As long as temperature and pressure remain constant, the changes in phase occur at the same rate.

    Pressure and/or temperature changes affect that balance, by favoring increased condensation or evaporation, depending on what changed and the direction of that change. Eventually, a new equilibrium point will be reached. However, that takes time and the system will be out of balance until then.

    We have forced air heating in my house. The fan runs continuously at 50% to circulate air and the heater and humidifier cycle on and of as needed. Pumping hot, humid air into the basement reloading room, which is cooler than the rest of the house favors an increase in the rate of condensation, even though the relative humidity is not 100% (dew point has not been reached). The process reverses when the heater shuts off; however, I don't think it is completely reversed by the time the heater comes back on. I can also tell you that when it is really cold outside and the relative humidity is low, my humidified doesn't come close to keeping up, and my powder bushing will throw a .2 grain lighter than normal charge. As much as .3 grain if the air is really dry.
     
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