leaving powder out overnight

[Benjerman08]

We all know that leaving powder exposed for long periods can lead to problems. My question is this: If powder is left out exposed overnight (dry climate), are there any problems that can occur? If I am loading into the evening and want to resume the next day, should I still re-canister it? Thanks.

 

[jonbearman]

I wouldnt worry if it is a dry climate however your powder measure will darken with age the longer it is exposed to powder.My set up is in a controlled atmosphere especially during the wet months.I have never had a problem with leaving it in a powder measure for a day or so.I normally empty my electronic powder measure to avoid tinting the hopper tube.High heat and moisture is the powders enemy.

 

[fdshuster]

I keep my powders in their tightly sealed cans------all the time. The only time the lid is off is when I'm filling the powder measure.

When the cases are charged with powder, the bullets are immediately seated.

 

[jo191145]

You should see no problems. I've been known to leave powder in the hopper for long periods as long as its not the soupy summertime.

And I'm on the opposite side of the spectrum from fdshuster.
I like to open new jugs of powder to let them "breathe" a few days before load development ;D
Once you crack that hermetic seal they're exposed to varying atmospheric conditions. I prefer to get any possible change over all at once before using. Probably more superstition than fact with a side of lazy thrown in on my part

 

[fdshuster]

jo191145: Just another thought: How does the powder laying at the bottom of the can "breathe" at the same rate as the powder at the top, or for that matter, how does it "breathe" at all being covered over by everything on top? Just askin, no argument intended or implied, I'm always open to suggestions.

 

[BoydAllen]

One may measure change in powder with a scale, and with a chronograph. The weight per volume CAN change over time, as well as the number of particles that make up a given weight. The question is whether the rate, or amount of change is enough to matter for your application. If the humidity is relatively constant in your loading room, there may be some advantage in conditioning your powder by exposing it to those conditions for a period of time. Some shooters who have done this sort of thing, have spread the powder in some sort of tray and then returned it to a bottle. This is getting down to some pretty fine stuff, and before I took any elaborate steps, I would do some testing. I return power to the container that it is stored in at the end of a loading session, and have come to the opinion that I probably should pay more attention to keeping the lid on my measure.

 

[savagedasher]

I have talked to bench rest shooter that did for ever they would put in a pan to let it breath so I don't feel it would make any difference. Good Shooting Larry

 

[Greyfox]

I use an RCBS Chargemaster. I never put the lid on it and I have been known to leave powder in the hopper for a couple of weeks at a time. I have never seen any problems. You will find that as you chase accuracy that there are any number of procedures that people use for precision loading. Some (many) of these will show absolutely no changes on the target, but people still do them and insist that they must be done. I could list several of these and create all sorts of things for people to argue about, but I won't. Don't be concerned about leaving the top off overnight or "letting it breathe", you won't see a difference either way.

Rick

 

[jo191145]

jo191145: Just another thought: How does the powder laying at the bottom of the can "breathe" at the same rate as the powder at the top, or for that matter, how does it "breathe" at all being covered over by everything on top? Just askin, no argument intended or implied, I'm always open to suggestions.

I use no scientific rationale in my shooting habits. I prefer good ol VooDoo

This little superstition derived way back when I was just learning to reload. Upon opening a fresh can of Varget I noticed that sharp acidic odor from the powder. Loaded up some cases and went outside to try them. Happened upon what I thought was a sweet spot. The next day that sweet spot was gone and velocity was way off.

There could be a million other mistakes I made that day but I still let that odor bleed off new powder to this day. VooDoo seems to work for me although the neighbors are sometimes perturbed to see me dancing around a target at midnight holding a bottle of rum and dead chicken.

 

[BoydAllen]

There was a well done test involving 133, that was published in Precision Shooting, that proved that moisture content of powder has considerable effect on velocity, and the weight of a given number of particles of powder. The weight difference between fully dried and fully humidified was 2%, and the velocity difference was something like 320 FPS. Freshly out of a newly opened container powder was between these extremes, and the method used to vary the moisture content was intentionally designed to take the powder to difference in moisture content, that I believe one would not normally experience. Nevertheless, it was an interesting and well done experiment. I would not be so quick to reject looking at this with a chronograph and scale. Some of us load in more stable environments than others.

 

[lrgoodger]

I'm with Rick. While it is indisputable that moisture intrusion affects powder weight and burn rate, it is highly unlikely that a drastic enough change will take effect overnight to make a difference on the target.

If one had a hopper that had been open for a while in extremely humid weather and began loading with that and ran the hopper empty, then opened a fresh can of powder and finished loading, there could possibly be a slight POI change between the two moisture states. I would advise against mixing such loads for a competition.