I was snowed in for 4 days. Food running low.
Anybody install hygrometers on their powder keg caps?
- Thread starter fatelvis
- Start date
Rick300
Gold $$ Contributor
Well that explains it
Not me man. Just got done pointing up some bullets. Relative humidity in my basement was fine.
I'm assuming that there is some sort of concentration coefficient between the powder and the air and that it also likely changes with temperature. Doesn't really matter though. I know from testing that if I speed up the drying of the powder with desiccant to a targeted level, the new lot of powder matches the last lot to a much larger degree than if I hadn't. I can set that target with the dew point of the air above the powder if I allow enough time for equilibrium to establish. I'm not the only one that has tested this. I'm just trying to point out a limitation with the most commonly used metric. Dew point is available on the Kestral Drop so it's not a huge deal.
Yes, RH is a proxy for the powder moisture level. I'm quite sure, from testing, that all the moisture isn't locked into the powder. It is likely at a higher concentration in the powder than the air and the powder certainly holds a much greater mass of water.
Nobody is putting desiccant in their powder jugs and leaving them. The humidity packs are being used to preserve the as shipped moisture levels. I started there and soon figured out I'd be starting over with load development for pretty much everything in the safe.
My excuses for spending too much time on the internet are:
From a past life, I puke prose pretty quickly
The wife had a hip replacement a few weeks ago
Too wet to shoot this week and kinda cold in the garage to be loading.
FDCaptain
Gold $$ Contributor
Way too much time on your hands, and too much busy work for the casual shooter.
charlie b
Gold $$ Contributor
As an engineer I do like a good test series of just about anything. Setting up a test that gives meaningful results is very difficult. Moisture levels in powder is something of interest. As is the differences in shooting in dry climates vs wet climates. And how long does it take for the powder to absorb the moisture.
Probably why I like shooting. Every day is a different test setup. If only I could measure all the test variables I'd be a happy camper
And, no, I am not restricted by winter out here. It was 70F here this afternoon. Spent 3hrs at the range this morning when it was only 55F. Just got done documenting my targets and initial analysis. Fun times.
Probably why I like shooting. Every day is a different test setup. If only I could measure all the test variables I'd be a happy camper
And, no, I am not restricted by winter out here.
It was 70F here this afternoon. Spent 3hrs at the range this morning when it was only 55F. Just got done documenting my targets and initial analysis. Fun times.Rich S
Silver $$ Contributor
Several sources have posted some pretty interesting results. Bottom line humidity can definitely change your tune. I ran into it that a few years back. My loads were running too fast and I kept dropping my powder charge. This was with Varget in a Dasher. I loaded some rounds with powder from a new jug from the same lot. My velocities returned to my initial charge/load data. I bought some hygrometers and measured the RH. The 1st jug had a lower RH. I assume it was due to my reloading area having a lower RH during the dryer winter months. I didn’t do a real scientific test but did play with different levels of moisture to see the affects. For one test I hung a damp sponge in a jug with about 1 lb of powder. The RH was around 70. I loaded 5 rounds and shot them along with others from a jug (same lot) with a 50 RH. I’m thinking it was over 30 fps difference.As an engineer I do like a good test series of just about anything. Setting up a test that gives meaningful results is very difficult. Moisture levels in powder is something of interest. As is the differences in shooting in dry climates vs wet climates. And how long does it take for the powder to absorb the moisture.
Probably why I like shooting. Every day is a different test setup. If only I could measure all the test variables I'd be a happy camper
And, no, I am not restricted by winter out here.
I’ve been shooting the last several years using the humidity packs. Im convinced it has helped me stay in tune more consistently.
BTW. I don’t think you want too dry of powder either. With limited testing I saw ES increase with low RH. I believe most powders leave the OEM around 50-55 RH.
Can you see it on target - yep.
Spacegunr
Silver $$ Contributor
I have thought about getting some of these. I like the idea anyway.
Don't understand how they can reach a specific %RH. Doesn't make sense. They absorb moisture continually going thru various RH levels until the Pak cannot absorb more moisture and they quit working. You need to weigh the paks periodically to see when they quit working.
The Boveda packs are not desiccants. They're something else that maintains a water vapor pressure around themselves.
I read an article by Litz at Applied Ballistics that started me into investigating powder moisture level impacts. The highlight reel went something like this:
Bought a Kestrel Drop and tested my stash of powder. Anything I'd had over a year was 42-44% RH. I tested a new jug when it arrived, and it was 58% RH. Yes, I was using RH when I started.
Bought some of the 67 gram 58% RH Boveda packs and dropped them in the new and a couple of the older 8# jugs. I rotated the older jugs whenever I thought about it to mix the powder. After a month, I pulled the Bovida pack and dumped the Drop into the jug. The RH in the jug started at room level ~38% and rose to 54% over a couple hours. The Boveda pack had raised the moisture in the powder and the powder was now acting as the Boveda pack. I was surprised by this given the large difference between the weight of the powder and that humidity pack.
Cool, now my powder was back to the way the manufacturer had shipped it. Loaded up a pressure ladder and the velocities had tanked. The light goes on that if I go down this path, I'll have to redo load development for my entire safe. I'm a cartridge whore, that would be a lot of work.
Another light that went on was the humidification process takes time on the order of weeks, it was likely there is some variation in humidity in the jug. I started dumping powder into small paint buckets and mixing it before using it. Used dryer sheets are your friends here.
I shoot ELR and go through a lot of powder. At some point, I wound up with jugs I needed to use that were in an intermediate moisture state. I decided to try to speed the drying process up. Did some research on desiccants and found there were a few types that were readily available and cheap. They differed in the vapor pressure they could pull air down to. Vapor pressure is yet another way of looking at moisture in air. I've had the air/water properties calculator I presented in an earlier post on my desktop since the '90s but it hadn't occurred to me to check what insights it might provide for reloading now that I was tracking and manipulating moisture levels. That's when the limitations on using RH for this became apparent and I switched to Dew Point. For my outside voice anyway. I'm using mass fraction internally.
Desiccants are cheap. The drying process goes faster the more of it you have and the larger the surface area it's working on. Started with some Retumbo. It took about 36 hours to lower the RH to the "used" level. Put the powder back in the original container without the desiccant and checked the moisture. It was still at the target level. Loaded up some ammo and it was a seamless transition from one jug to the next on velocity. This approach should also suppress the formation of layers of different moisture levels.
None of this is terribly complicated. Anybody can repeat or do their own version of it. It does take time and a couple hundred dollars. The Kestrel drop alone was ~$100 and the larger Boveda packs are not cheap either. I'm aware of others that are testing the impact of moisture on velocity spreads. I'm testing lowering moisture even further to speed up powder enough to uncompress loads without dropping to the next faster powder. I don't know about any accuracy testing but my crowd trends towards ELR/PRS.
I read an article by Litz at Applied Ballistics that started me into investigating powder moisture level impacts. The highlight reel went something like this:
Bought a Kestrel Drop and tested my stash of powder. Anything I'd had over a year was 42-44% RH. I tested a new jug when it arrived, and it was 58% RH. Yes, I was using RH when I started.
Bought some of the 67 gram 58% RH Boveda packs and dropped them in the new and a couple of the older 8# jugs. I rotated the older jugs whenever I thought about it to mix the powder. After a month, I pulled the Bovida pack and dumped the Drop into the jug. The RH in the jug started at room level ~38% and rose to 54% over a couple hours. The Boveda pack had raised the moisture in the powder and the powder was now acting as the Boveda pack. I was surprised by this given the large difference between the weight of the powder and that humidity pack.
Cool, now my powder was back to the way the manufacturer had shipped it. Loaded up a pressure ladder and the velocities had tanked. The light goes on that if I go down this path, I'll have to redo load development for my entire safe. I'm a cartridge whore, that would be a lot of work.
Another light that went on was the humidification process takes time on the order of weeks, it was likely there is some variation in humidity in the jug. I started dumping powder into small paint buckets and mixing it before using it. Used dryer sheets are your friends here.
I shoot ELR and go through a lot of powder. At some point, I wound up with jugs I needed to use that were in an intermediate moisture state. I decided to try to speed the drying process up. Did some research on desiccants and found there were a few types that were readily available and cheap. They differed in the vapor pressure they could pull air down to. Vapor pressure is yet another way of looking at moisture in air. I've had the air/water properties calculator I presented in an earlier post on my desktop since the '90s but it hadn't occurred to me to check what insights it might provide for reloading now that I was tracking and manipulating moisture levels. That's when the limitations on using RH for this became apparent and I switched to Dew Point. For my outside voice anyway. I'm using mass fraction internally.
Desiccants are cheap. The drying process goes faster the more of it you have and the larger the surface area it's working on. Started with some Retumbo. It took about 36 hours to lower the RH to the "used" level. Put the powder back in the original container without the desiccant and checked the moisture. It was still at the target level. Loaded up some ammo and it was a seamless transition from one jug to the next on velocity. This approach should also suppress the formation of layers of different moisture levels.
None of this is terribly complicated. Anybody can repeat or do their own version of it. It does take time and a couple hundred dollars. The Kestrel drop alone was ~$100 and the larger Boveda packs are not cheap either. I'm aware of others that are testing the impact of moisture on velocity spreads. I'm testing lowering moisture even further to speed up powder enough to uncompress loads without dropping to the next faster powder. I don't know about any accuracy testing but my crowd trends towards ELR/PRS.
The FAQ in this one is informative and several notches beyond what's found on the Interweb.
Not a stupid question. It's probably the one that starts the silliness in most cases.
The answer is it's a lot larger than most realize and there isn't a safe universal answer.
As was pointed out earlier, we're using the moisture in the air to estimate the amount of water in the powder. My position is given enough time, it's a useful estimate on the impact to pressure/velocity but I wouldn't try to back out the amount of water in the powder. I also don't think it's just a weight thing. The chemistry/thermodynamics are likely also affected.
If that's not a hypothetical case and you're starting with a max load with 85% and need to do it in one jump, be careful.
I used to roll my eyes at BR shooters commenting humidity affected their tune. I'm not a BR shooter, but after thinking through the loading at the bench between strings thing, I'm not rolling my eyes anymore. If I was a BR shooter, I'd take my first clue on the charge weight changes from the chronograph. That's not a suggestion for BR shooters, I realize many of them despise chronos. That's the first thing this long range shooter would try if he found himself cornered in a BR match. I suspect it's not the final answer but might be a first step in the right direction.
The answer is it's a lot larger than most realize and there isn't a safe universal answer.
As was pointed out earlier, we're using the moisture in the air to estimate the amount of water in the powder. My position is given enough time, it's a useful estimate on the impact to pressure/velocity but I wouldn't try to back out the amount of water in the powder. I also don't think it's just a weight thing. The chemistry/thermodynamics are likely also affected.
If that's not a hypothetical case and you're starting with a max load with 85% and need to do it in one jump, be careful.
I used to roll my eyes at BR shooters commenting humidity affected their tune. I'm not a BR shooter, but after thinking through the loading at the bench between strings thing, I'm not rolling my eyes anymore. If I was a BR shooter, I'd take my first clue on the charge weight changes from the chronograph. That's not a suggestion for BR shooters, I realize many of them despise chronos. That's the first thing this long range shooter would try if he found himself cornered in a BR match. I suspect it's not the final answer but might be a first step in the right direction.
I think most BR shooters rely on the shape of their groups i.e. how small or big they are. There is the question of the amount of moisture in the air and how much it affects the flight of bullets as well. Moisture is a bugger ain't it?
I once read on one of these forums that powder adsorbed moisture almost immediately when a container was opened. If that be so, it seems like a slippery slope and nearly impossible to deal with.
The moisture transfer process is actually pretty slow. Not sure if it's absorbed or adsorbed but lean towards absorbed with partial pressures as the driving potential. Powder is pretty porous, so it might not matter that much. Leaving a jug open all day isn't a good idea. Leaving the top off a powder measure and refilling it as you load probably isn't either if there is a large difference in moisture between the air and powder. If you work with the top on, dump the last inch of powder back into the jug, mix it, then refill the measure, it'll cover 80% of the problem for not a lot of effort. Adding one of the Boveda packs at the same RH as the powder under the cap of the measure is the next level.
The reason I'd roll my eyes about BR shooters and moisture was it's a third order effect on external ballistics and certainly doesn't affect group sizes through that mechanism. Even with ELR, parking the humidity estimate at 50% and leaving it won't be your biggest problem in the firing solution estimate. If you have some sense of it, breaking it into 25%, 50% and 75% stomps it into the noise. The only way I see it affecting 100 yd BR groups is by way of the internal ballistics.
The reason I'd roll my eyes about BR shooters and moisture was it's a third order effect on external ballistics and certainly doesn't affect group sizes through that mechanism. Even with ELR, parking the humidity estimate at 50% and leaving it won't be your biggest problem in the firing solution estimate. If you have some sense of it, breaking it into 25%, 50% and 75% stomps it into the noise. The only way I see it affecting 100 yd BR groups is by way of the internal ballistics.
fatelvis
Silver $$ Contributor
Actually, I don't have that much spare time, as I'm still working, but I've been seeing big fluxuations in velocity due to burn speed (dryness of powder) after opening a new bottle of powder of the same lot #.
fatelvis
Silver $$ Contributor
I didn't know those existed. I like the idea! Although they are very pricey.
FDCaptain
Gold $$ Contributor
I live in Colorado; humidity is low 99% of the time, I have the same desiccant container in my safe for 4yrs. haven't had to re-charge it yet.
Does it matter what the Rh is?????
- Pour the powder from the container to a powder measure. It sits in the powder measure at room RH for many minutes.
- Powder measure to a scale pan at room Rh.
- Scale pan to a funnel on top of a cartridge case at room Rh.
Relative humidity (RH) has a temperature component. Of you measure the RH in a sealed container, the RH will decrease as the temperature increases, though the amount of water in the container remains the same. At the plant we use the dew point to measure the moisture in the air.
Below is a link that does a decent job explaining.
iere.org
Below is a link that does a decent job explaining.
How Much Moisture Is in the Air? - The Institute for Environmental Research and Education
How Much Moisture Is in the Air? The amount of moisture in the air is constantly changing, varying dramatically from […]
iere.org
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