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Posted: 3/4/2015 10:36:36 AM EDT
My record keeping is for $h%&, so I could be a bit wonky on this. But bear with me.

I seem to recall my plinking pistol load for 9mm is 4.1gr of American select, and through my Lee auto disc I'd get +/- 0.1gr which is fine with me. My workshop is now very very cold, in the 30's right now. My powder hopper is prepped with graphite powder, and I do run a baffle in there(which is a change since I started, so this could be the difference as well). My drops now are 3.9gr. Now it's not a HUGE change, but I was just wondering if temps had any effect in powder drops? I know static can, which generally static is worse in winter and dry areas, but this is a basement workshop and humidity is controlled to a point and I think it was about 40-50% the other day in the shop. Just curious.

Link Posted: 3/4/2015 11:31:06 AM EDT
The plastic disks may be contracting a bit in the cold. Just a thought.
Link Posted: 3/4/2015 11:51:04 AM EDT
I vote baffle.
Link Posted: 3/4/2015 12:07:24 PM EDT
Probably the weighing method that is a small amount. How long have you been doing this(setup),since last summer or since 1972?



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Link Posted: 3/4/2015 2:13:48 PM EDT
Link Posted: 3/4/2015 2:15:26 PM EDT
Interesting...Is it practical to heat up the area enough that you could see if the temp. does make a difference ? Maybe move it to a warmer area , let it acclimate and test ?
Link Posted: 3/4/2015 2:26:23 PM EDT
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Originally Posted By dryflash3:

Temp and humidity effect my beam scale, no problem I zero it before use.

You didn't mention how you are weighing powder. Digital or beam? Cheap digital?

I'm thinking you problem is your not settling the powder before you start weighing charges.

So no, temp does not effect how powder is thrown from a powder measure.

The user not being consistent has a great effect.
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Originally Posted By dryflash3:
Originally Posted By RandyLahey:
My record keeping is for $h%&, so I could be a bit wonky on this. But bear with me.


I seem to recall my plinking pistol load for 9mm is 4.1gr of American select, and through my Lee auto disc I'd get +/- 0.1gr which is fine with me. My workshop is now very very cold, in the 30's right now. My powder hopper is prepped with graphite powder, and I do run a baffle in there(which is a change since I started, so this could be the difference as well). My drops now are 3.9gr. Now it's not a HUGE change, but I was just wondering if temps had any effect in powder drops? I know static can, which generally static is worse in winter and dry areas, but this is a basement workshop and humidity is controlled to a point and I think it was about 40-50% the other day in the shop. Just curious.



Temp and humidity effect my beam scale, no problem I zero it before use.

You didn't mention how you are weighing powder. Digital or beam? Cheap digital?

I'm thinking you problem is your not settling the powder before you start weighing charges.

So no, temp does not effect how powder is thrown from a powder measure.

The user not being consistent has a great effect.
very possible it IS me. I did throw about 5-10 charges before weighing though. I use both a Lee beam and a cheap Frankford digital to backup weights. They are within 0.1gr of eachother and consistent in the drop I've noticed.
Link Posted: 3/4/2015 2:27:15 PM EDT
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Originally Posted By popnfresh:
Probably the weighing method that is a small amount. How long have you been doing this(setup),since last summer or since 1972?



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Just started reloading this past fall. Not a ton of experience sorry!
Link Posted: 3/4/2015 3:16:39 PM EDT
Link Posted: 3/4/2015 3:41:54 PM EDT
[Last Edit: 3/4/2015 3:45:10 PM EDT by RandyLahey]
American select powder. Small disc/flakes

I use the Frankford scale to double check my beam scale. I have heard of the drift, and I would say that the only time I may have noticed drift is if I'm weighing over 10-15 charges w/out resetting tare weight. I usually don't weigh every charge. Only weigh when I confirm charges after the press sits for awhile, or if I make deliberate changes.



Link Posted: 3/4/2015 3:54:17 PM EDT
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Originally Posted By dryflash3:
Franklin Digital is not safe to use to measure powder. Too much drift.
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Indeed.

I had one, and my first observation was that it didn't seem to actually calibrate, just verify that it was within some unknown spec. Then I noticed that it would read differently based on where I put on object on the scale. Also, it would read differently based on how firmly I set the object down. Then I observed it measuring weights differently as time went on. Presumably, that was due to "warming up", but with its auto-off feature, you can't just leave it on.

I sent it back, it is far too untrustworthy.
Link Posted: 3/4/2015 5:22:32 PM EDT
Link Posted: 3/4/2015 5:45:06 PM EDT
Both temperature and humidity can effect the density of powder. For years, I used a RCBS Uniflow, and it would drive me crazy that each time I used it, I had to re-measure slightly, or re-calibrate the scale slightly.

Then I learned about loading by volume vs. by weight. Someone told me Lake City Match ammo is all loaded by volume, not weight of the charge.

So now I just use the same volume each time I throw powder (either in the Uniflow or the Lee Autodisk,) and when I weigh, I weigh for consistency, not absolute weight. And I stay away from the max charge.

i'm much happier now.
Link Posted: 3/9/2015 10:15:44 AM EDT
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Originally Posted By DaveSpud:
Both temperature and humidity can effect the density of powder. For years, I used a RCBS Uniflow, and it would drive me crazy that each time I used it, I had to re-measure slightly, or re-calibrate the scale slightly.

Then I learned about loading by volume vs. by weight. Someone told me Lake City Match ammo is all loaded by volume, not weight of the charge.

So now I just use the same volume each time I throw powder (either in the Uniflow or the Lee Autodisk,) and when I weigh, I weigh for consistency, not absolute weight. And I stay away from the max charge.

i'm much happier now.
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+1 on this. The benchresters use volume. They should know.
Link Posted: 3/9/2015 11:07:00 AM EDT
yep, sources of error could be the scale as well, especially digital scales.

If you leave the powder in the hopper over days, i would expect it to be heavier as it absorbs the ambient moisture. Sealed in a can it should be nearly moisture stable until next time you open it. Wide swings of temp could cause the air to creep in and out of the can if the seal isnt' so great.

Just thinking of possible causes.

Would be interesting to shoot the old load and the later load over a chronograph to compare them. About 10-20 rounds of each to get a good number.
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