Gunpowder or scale?

feelinducky

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I did some reloading on Friday night. I ended up putting powder in 6 cartridges that I didn't seat a bullet in. I kept them in the reloading tray put them up on a shelf in the garage and left them. Last night I went to reload again and took these one at a time and reweighed each charges. I made sure each case was empty. Each charge was about .2-.3g less than what I had originally loaded them at. What is that all about? Does powder loose moisture? I thought it would be hydrophilic. Is this a scale issue? RCBS 505. Does powder loose weight (moisture) if it is not covered?

Thanks
 

FearNoWind

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I've never tested the volatile chemical characteristics of gunpowder but considering that the recommendation is to keep it "tightly" closed in storage and that the containers are air tight, along with the fact that an open container emits a distinct odor in open air, I'd say you probably lost some chemicals to evaporation. But that's just a guess.
 

g0rd0

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I've never tested the volatile chemical characteristics of gunpowder but considering that the recommendation is to keep it "tightly" closed in storage and that the containers are air tight, along with the fact that an open container emits a distinct odor in open air, I'd say you probably lost some chemicals to evaporation. But that's just a guess.
what he said
 

gohring3006

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It would be interesting to see if performance changes using strain gauges. And a chronograph. If we get evaporation and loss of weight could we over charge a case. hmmm. Makes me wonder-----
 

rcairflr

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My guess would be scale issue, but you have me curious, i am going to set some powder out in the garage and see if it loses weight.
 

rcairflr

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6:46 24Sept2014, just put 50.05 grains of H335 in the garage.

Checked the accuracy of my scale with calibrated weights and remeasured the powder sample 3 times. Each time it repeated at 50.05 grains.

Saturday morning I will reweigh the open powder sample and publish the results.
 

feelinducky

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I wish I would have measured the temperature in the garage. It does get pretty warm in there, and living in California we have very little humidity.
 

gohring3006

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It would still be interesting to know it actually happens no matter the atmospheric conditions.
 

dkhunt14

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I was loading for a match one night and I got tired so I went to bed. Left a charge of H 4350 sit on the scale. In the morning the scale read heavier. I thought it must have drifted overnight. I poured the powder in my other pan and sat the pan back on the scale and made sure it was zeroed. I poured the powder back on the scale and it was the same. It gained over night. Now I live in Pa and the humidity is high here. I believe if is was real low humidity it could go the other way. Matt
 

feelinducky

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I did some googling about it and most guys were talking about water absorption. I forgot to mention that I used the same powder and added about .2 grains to it and they seemed hotter.
 

dkhunt14

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It was a couple of years ago and I can't remember but it seems it was about .2. If you put it in a garage in heat and low humidity it probably dried out and needed to go the other way. Actually in your case since the powder was already weighed you should have left it the same. Matt
 

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