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PW powder drops go light...

Discussion in 'Uncategorized Threads' started by Mac V, May 1, 2007.

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  1. Mac V

    Mac V Guest

    This falls into the category of "I wonder why?" rather than "I gotta find an answer!", but

    When I use my PW 900, I reload about 3 flats in a session. I check the powder drop weights about once every 50 shells or so and I can count on them being consistent. And I always weigh the first and last drops of the session.

    So it puzzles me when I end one session, start another 3 or 4 days later and find the the powder drops are now consistently .2 or .3 of a dram (On Edit: No, I really mean grains!)lighter or heavier. I've not added or changed anything from one session to the next. I have usually attributed this to environmental changes. If I chose to, I could load all day and the new drop weights would stay light, or heavy.

    I have a wide-enough range of powder bushings (stock and modified) so I can change the bushing and re-establish original weight, but is that what I really want to do? If I'm still throwing the same volume of powder as before, there must be something else I'm weighing beside powder.

    Should I correct for the change or not?? Is the change significant?

    Mike
     
  2. Ahab

    Ahab Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    3,651
    Wow! A difference of .2 to 3 drams? That's a 5 to 8 grain difference!

    My guess is that your scale is screwed up!

    Now....if you meant .2 to .3 grains...no biggy...humidity and temperature will cause that much change. Also .3 grains will not cause a significat change in pressure or performance.
     
  3. Mac V

    Mac V Guest

    <blockquote>"Wow! A difference of .2 to 3 drams? That's a 5 to 8 grain difference!

    My guess is that your scale is screwed up!"</blockquote>

    Aw, feldercarb!!

    I DID mean grains. I have no clue as to where "drams" came from. I use a RCBS 0-5 beam balance and it's not even calibrated in drams.

    I did figure that it was weather related but I don't see big changes in either relative humidity or temp where I reload.

    Thanks for pointing out my dyslexic screw-up!

    Mike
     
  4. Jason Hassler

    Jason Hassler Member

    Joined:
    Jan 29, 1998
    Messages:
    302
    Here is a thought on this topic- Perhaps keeping an eye on air currents in the room might make a difference. I have noticed with my scale that if there is any air current in the room (a fan or open window nearby) it will make the reading on the scale inconsistent. Seems obvious but I thought it was worth mentioning.
    Jason
     
  5. dverna

    dverna Active Member

    Joined:
    Jan 29, 1998
    Messages:
    2,717
    Empty the powder measure after every session.

    Don
     
  6. buckwheat

    buckwheat TS Member

    Joined:
    Jan 29, 1998
    Messages:
    156
    Ground your reloader.
     
  7. phirel

    phirel TS Member

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    9,556
    Mike- Is it possible that the problem is with your scale and not the reloader? Static electricity is another possibility but static electricity cannot build up on the press without some movement.

    I do not have this problem with my PW and I do not drain the powder from the hopper when I finish a loading session. Sometimes the powder remains in the hopper for several months.

    You did state that you weigh the last round. I suggest that you weigh this last shell and replace it in the press. Write the weight on the side of the hull. Then, before you begin your next session, weigh the same charge again. If the indicated weight on your scale changes, that would identify the problem. Actually, you should weigh your last powder charge and 3-4 other little things on your loading bench (spent primer, washer, dime, etc.)

    Pat Ireland
     
  8. Mac V

    Mac V Guest

    Pat,

    My reloader is bolted down so two of the bolts pass through the steel frame of the bench and the bench is anchored to the floor.

    I don't empty the powder either.

    I weigh the first and last powder charges, not the shells. I'm puzzled by your suggestion to weight the last shell and "replace it in the press". How would I do that with a PW?

    I do periodically check the zero on the scale against a brass test weight and as long as I haven't moved the scale, the zero stays the same. I thought about the scale as a problem so I've made arrangements to borrow a scale to check mine against. I've found that if I can restrain myself from messing with the powder bushing to correct the weight, it will return to its original reading eventually.

    Thanks for the input...more things to consider.

    Mike
     
  9. miketmx

    miketmx Well-Known Member

    Joined:
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    Messages:
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    I have a PW 900 loader and it is in the basement of our house. I don't have the variation that you get but I only use Alliant Red Dot and Green Dot. A denser fine grain powder may be more subject to changes in humidity or temperature.
     
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