Optimum % of moisture in powders

[CJ6]

Is there an optimum percentage of moisture when loading or even storage of powder? IS THERE SUCH A THING
The question was raised on another forum and it was proposed to DRY your powder down (OPEN JUGS SITTING NEAR FURNACE VENT) others suggested silca packs inside of the containers.
They're not talking about powder that has been exposed to water/excessive moisture but as standard practice.
This is NOT something I'd even consider doing.
Your thoughts.

 

[whatsupdoc]

Accurately measuring moisture content in a material is not so easy to do in a lab
forget at home.

 

[M-61]

The question was raised on another forum and it was proposed to DRY your powder down

How would one dry their powder UP?

 

[CJ6]

Good question. Set it on a humidifier???

 

[Mulligan]

Drying powder changes the burn rate. Sometimes very significantly.
As an example,
As part of an experiment I was doing, I dried several varieties of powder that are typically used for short range benchrest. Here in Western Colorado, daytime temps in the 90's and relative humidity near 10% is fairly common. In short range benchrest, shooters load at the range, their powder is in a dispenser for hours at at time.
I decided to test how it could change. I set out shallow containers with weighed charges and weighed them again every 15 min for an hour. 80% of the reduction in weight was in the first 15min. Some varieties of powder lost .3gr, for a 28gr charge, that is a LOT! The velocity increase from the dried powder was as high as 73FPS, Most were in the 40-50FPS range.

I think most powders are made in plants that maintain somewhere near 50% RH. This gives the product the "dead fuel moisture" the powder makers are after.
Dead fuel moisture is a term I am used to, I am sure powder manufactures have a different term they use.

CW

Edited to correct grammer.
CW

 

[CJ6]

With (according to your tests) the 80% changes in 15 minutes, it would seem that would also work in the opposite direction when loading negating the drying process.

 

[Mulligan]

With (according to your tests) the 80% changes in 15 minutes, it would seem that would also work in the opposite direction when loading negating the drying process.

Sort of,

What I am saying is this.

The powders I tested, were about 80% normalized in 15 min. (By the way, I did test a dual-based powder just to see how it would react, and It changed the least of all the powders I tested).
I do not know they would respond in say a 75% RH environment?
What I can say it they dry out fast in the arid climate of the intermountain west.

CW

 

[CJ6]

So how did this effect your loads then? Velocity Pressure.

 

[Jager]

It's not so much that a particular amount of moisture within a powder is optimum... it's much more about having the same amount of moisture all the time.

There's the rub.

 

[Mulligan]

So how did this effect your loads then? Velocity Pressure.

In post 5 above, I listed some velocity changes I seen on that day.

I hope this helps
CW

 

[CJ6]

It's not so much that a particular amount of moisture within a powder is optimum... it's much more about having the same amount of moisture all the time.

There's the rub.

And that's the thing. Keeping it consistent.
If you dry down your powder (at home) bring it to the range, set up your loading gear, pour your powder into the measure all the while the powder is gaining moisture, how can you keep any sort of consistency?

 

[DLT]

I would say where it stays majority of the time, what ever the humidity is there. Then it should stay close to the same all the time. Truth is I store all of mine in the house in a closet and it is what it is. I don’t have the ability to shoot the difference if there was one

 

[CharlieNC]

I suspect the best answer would come from the powder manufacturers.

 

[CJ6]

I suspect the best answer would come from the powder manufacturers.

I do have an email out to both VV and Hogdon.
I am interested in what they may have to say.

 

[Ruger15151]

I do have an email out to both VV and Hogdon.
I am interested in what they may have to say.

They claim that powder is packaged with 50% humidity. That might be your answer.

I use these to maintain that humidity once my jugs are opened and exposed to the environment.

Amazon.com

These are for 8 pound jugs and they make smaller ones that I use in 1 pound bottles.

Since using them I have found my velocities are much more consistent throughout the year.

 

[whatsupdoc]

How would one dry their powder UP?

Many ways, but manufactures heat it to dry it.

 

[Jeff Porter]

I had a jug of H4895 that was stored in a non climate controlled area. Was loading for new rifle in 6BRA and was about 100 fps under what others were seeing. FB moderator suggested drying the powder. So I put a pound on a pie plate in a food dehydrator at 105 F for four hours. Velocity came up and the SD was mid single digits with the dried powder.
Since this time I have routinely dried my H4895 and had very consistent results with less lot to lot variability.
Your mileage may vary. But it works for me. Just dried 2 pounds last night.

 

[Jeff Porter]

Here is a jump test I ran on a new barrel with 105’s with dried powder. Seating at the bench, I seated 12 at 1.810 and shot a blind group ( it was getting dark and I could not see holes lol) Called two shots left, one shot low right. Other 9 broke center.

This 9 shot group shot from a sling went a hair under 0.5 moa with SD of 4.5 ES of 15.4






Yeah - I’ll keep drying my powder for this rifle.

 

[M-61]

Many ways, but manufactures heat it to dry it.

Yeah. My point was UP . You dry something. It’s not up or down. You might up or lower a moisture percent.
And yes “heat it to dry it”

 

[tom]

It makes a difference, but in the little testing I did, the velocities moved a greater amount than the tune. For example, a 17% change moved the velocity 45 fps, which would require a .45 change in charge weight to get back to equal velocities. BUT, since I shot a 1,000 yard ladder on actual paper while recording speeds, the result was to only move .1 in powder to achieve the tune again. See below, it was "manipulated" 32% vs 49% for an example.







It is going to take on whatever it is stored at, whether it's sealed or not. The better it's sealed, and the larger the amount will just take longer to "get there" from testing Donovan had done and shared. I would let it be what you store it 99% of the time, and it's not going to move enough to matter having it on the road for a weekend. I do question the vial thing, since we saw changes happen faster to "small amounts", but I still do that out of convenience and store it differently than prior to testing.

About the snow, ya it wasn't the best few weekends to go build a range to shoot 1k!



But a guy has to do the work in the off season somehow!



Tom