How does humidity affect powder? A new experiment

[NamibHunter]

If you want/need to reduce bullet weld, try testing a batch of ammo without wet tumbling and removal of the carbon in the case neck. I’ve said for a long time that wet tumbling is counter productive for this reason.

Cold weld (not the same thing as galvanic corrosion!) relies on two very clean surfaces in close contact under pressure. In wet tumbled case necks, we have all of those present. The simple solution is to remove the “clean” part of the equation- either by leaving the carbon in the neck, or lube on the cases, etc. Some things work better than others, and as you found some things like your sealant don’t necessarily prevent cold weld.

Agree with your comments NOT to over clean the inside of the necks and leaving some carbon in place. I used to run an ultrasonic cleaner, and that over cleaned the 6.5 CM Lapua cases to a shiny state, inside and out. Had significant problems with cold weld if the ammo was left to stand (inside an air conditioned house) for more than a few days.

Once i switched to corn cob tumbling media via a standard vibratory tumbler, and left some carbon in the necks, SDs clearly got better (7-9 fps). Still had the odd round that would stick when reseating (1 in 10 or so), and ES remained a little high (low 30’s). So the problem was mitigated - just not completely solved.

On my new 300 WSM I went a different way: tumble the ADG cases in walnut media for a limited time (60 minutes, via a timer that turns off power to the tumbler), apply Neolube nr 2 to the inside of the neck, and i use HBN coated 225 ELDM bullets. So the bullets are lubricated too. SDs for large 30-40 shot samples came down from 8-10 fps (pretty good) for the 6.5 Creed and the 308, to 4-6 fps for the WSM. ES effectively halved, a very nice improvement. Reseating a box of ammo (40 rounds) that was done 2 weeks ago showed zero sticking bullets. Need to store a box of loaded ammo for 6 months or longer before declaring victory, but this approach is the best i have found so far.

Not sure if it was the Neolube, the HBN bullet coating, or the combo of the two that did the trick, but it worked for me so far.

 

[Yondering]

Agree with your comments NOT to over clean the inside of the necks and leaving some carbon in place. I used to run an ultrasonic cleaner, and that over cleaned the 6.5 CM Lapua cases to a shiny state, inside and out. Had significant problems with cold weld if the ammo was left to stand (inside an air conditioned house) for more than a few days.

Once i switched to corn cob tumbling media and a standard vibratory tumbler, and left carbon in the necks, it clearly got better. Still had the odd round that would stick (1 in 10 or so).

On my new 300 WSM I went a different way: tumble the ADG cases in walnut media for a limited time (60 minutes), apply Neolube nr 2 to the inside of the neck, HBN coated the 225 ELDM’s. SDs (30-40 shot samples) came down from 8-10 fps for the Creed, to 4-6 fps for the WSM. Reseating a box of ammo (40 rounds) that was done 2 weeks ago showed zero sticking bullets.

Not sure if it is the Neolube, the HBN bullet coating, or the combo of the two, but that worked for me.

Roger that. I’m interested to try the HBN but haven’t got around to it yet. Mainly just haven’t taken the time to find a good source. What do you use?

For cleaning, I’ve started adding some carnauba car wax to the corn cob media (which also has Dillon case polish). I use that mixture to remove lube from my sized brass; it does a great job on the outside with just a thin waxy coating left; on the inside it seems to leave a little more of the lube in place. That seems to be working pretty well to eliminate cold welding.

 

[NamibHunter]

Roger that. I’m interested to try the HBN but haven’t got around to it yet. Mainly just haven’t taken the time to find a good source. What do you use?

For cleaning, I’ve started adding some carnauba car wax to the corn cob media (which also has Dillon case polish). I use that mixture to remove lube from my sized brass; it does a great job on the outside with just a thin waxy coating left; on the inside it seems to leave a little more of the lube in place. That seems to be working pretty well to eliminate cold welding.

Thanks for the tip. A wax coating should help. New factory cases apparently have a wax coating too.

Well, I order HBN powder direct from David Tubb/Superior Shooting Systems. He adds an anti-copper fouling agent to his blend.

You could order from Amazon, but there have been reports of material being shipped that could be used to badly scratch glass, so not pure lubricant. Either contaminated material, or they simply shipped the wrong chemical. It also need to be of very small particle size, or it won’t impact plate properly on the bullets. The fly-by-night outfits are best avoided, i think.

That said, a buddy of mine uses microLubrol ultrafine grade (<0.5 micrometer), and he gets good results.

 

[NamibHunter]

Just ran an experiment: Skipped the Neolube nr 2 coating on the inside of the necks (with enough black carbon left in the neck from firing the round last time, and still using HBN coated bullets, same load): SD went up from 4-5 fps range to 7.6 fps, for 20 shots. So yes - i am going back to Neolube.

If you go search on Youtube for “Reloading Witch Doctor” you will find a video where he tests no lube, vs Neolube inside the neck only, vs Neolube on bullet plus neck (which got the best groups) in a superb 6PPC bench rest rifle. [Guy has a PhD and has won some BR medals, and works in a scientific research capacity, and he uses proper Statistics (T-test) to detect if there is enough evidence to believe the outcomes of his various experiments. Very dry, but informative. Don’t expect entertainment.]

 

[6.5SH]

 

[Yondering]

Thanks for the tip. A wax coating should help. New factory cases apparently have a wax coating too.

Well, I order HBN powder direct from David Tubb/Superior Shooting Systems. He adds an anti-coper fouling agent to his blend.

You could order from Amazon, but there have been reports of material being shipped that could be used to badly scratch glass, so not pure lubricant. Either contaminated material, or they simply shipped the wrong chemical. It also need to of very small particle size, or it won’t impact plate properly on the bullets. The fly-by-night outfits are best avoided, i think.

That said, a buddy of mine uses microLubrol ultrafine grade (<0.5 micrometer), and he gets good results.

Thanks for the tips. Agreed on the fly by night places; I'll order some from Tubb.

The neck lubing stuff in your other post makes a lot of sense to me. I'll have to watch those videos for more info when I have time.
Most lubes should act a a "contaminant" to prevent cold welding, but more than that, they can give a huge reduction in static friction, or stiction, which should work in our favor for more consistent neck/bullet friction.

 

[Haney]

I thought this was about HUMIDITY ?

 

[NamibHunter]

I thought this was about HUMIDITY ?

Fair point, sorry!

Not to make excuses, but I have a worry that humidity seeping into cases makes bullet weld worse. But not sure yet.

 

[NamibHunter]

Thanks for the tips. Agreed on the fly by night places; I'll order some from Tubb.

The neck lubing stuff in your other post makes a lot of sense to me. I'll have to watch those videos for more info when I have time.
Most lubes should act a a "contaminant" to prevent cold welding, but more than that, they can give a huge reduction in static friction, or stiction, which should work in our favor for more consistent neck/bullet friction.

Neolube nr 2 is also electrically conductive. Not sure if that matters here or not, but i vaguely recalls that corrosion chemical reactions tend to be electrolytic in nature, so it might have some bearing on its effectiveness. Or not!!

But I do know for sure that i’m WAY out of my depth on the chemistry aspect… Trained professionals need to step in…

 

[NamibHunter]

Back to HUMIDITY again…

 

[Doom]

I thought this was about HUMIDITY ?
midity


Fair point, sorry!

Not to make excuses, but I have a worry that humidity seeping into cases makes bullet weld worse. But not sure yet.

If that were true then the military would have required specific control of humidity for ammunition storage long ago.

 

[NamibHunter]

If that were true then the military would have required specific control of humidity for ammunition storage long ago.

Fair point. Bullet weld is a real phenomena (very badly named), but it is a secondary effect, and not something i would worry about with factory ammo, unless it is stored for 50 years.

If you want to get your ES of 30 fps down to 12-18 fps for shooting at a mile, then taking some basic precautions to mitigate bullet weld can be beneficial. Like seating long and reseating just before the match. Or painting the bullet and the inside neck with Neolube. Not needed for 400 yard 223 ammo.

 

[6.5SH]

If that were true then the military would have required specific control of humidity for ammunition storage long ago.

Other than exceptions for some specialty ammo typical "combat" ammo has sealer on the primer and the bullet.
More for it getting wet and staying reliable than humidity changes over time.

 

[memilanuk]

From Google...

https://www.sisweb.com/referenc/msds/neolube2.pdf

 

[6.5SH]

Even powdered graphite is nasty to be around. At least the liquid isn't going to make a cloud of dust.

Glasses, gloves and a solvent respirator are called for when handling it. If we are being honest those were needed for handling Hoppes and every other solvent of yore, but hardly anyone did.

 

[secondofangle2]

I’m a pulmonologist and I don’t wear a respirator for any of the aforementioned activities

 

[MarkyMark007]

Even powdered graphite is nasty to be around. At least the liquid isn't going to make a cloud of dust.

Glasses, gloves and a solvent respirator are called for when handling it. If we are being honest those were needed for handling Hoppes and every other solvent of yore, but hardly anyone did.

than I guess you don't do barbique... there is a 'tones' of powdered graphite... and you not only breathe it, you eat it.

but you are right, powdered graphite is not what you want in your lungs. in china, where they mine grapfite, whole area has damaged lungs and people die very young because of that.

 

[Yondering]

than I guess you don't do barbique... there is a 'tones' of powdered graphite... and you not only breathe it, you eat it.

but you are right, powdered graphite is not what you want in your lungs. in china, where they mine grapfite, whole area has damaged lungs and people die very young because of that.

That is not powdered graphite in wood smoke.

 

[secondofangle2]

Guys, powdered graphite is an occupational hazard if you are exposed to it daily over time. I don't think that counts for the little bits you're using for bullet lube. This is reminiscent of people (mistakenly) claiming that "fentanyl" dust in the air drops you dead.

https://www.cdc.gov/niosh/docs/81-123/pdfs/0306.pdf?id=10.26616/NIOSHPUB81123#:~:text=Effects%20of%20overexposure%20Repeated%20inhalation,graphite%20dust%20causes%20graphite%20pneumoconiosis.

 

[secondofangle2]

than I guess you don't do barbique... there is a 'tones' of powdered graphite... and you not only breathe it, you eat it.

but you are right, powdered graphite is not what you want in your lungs. in china, where they mine grapfite, whole area has damaged lungs and people die very young because of that.

Where is the pandemic of disabled gun cleaners disabled from Hoppes #9 then?

 

[memilanuk]

So... dragging this back onto the original topic...

@mc10 question for you: how well sealed do you think an average 'precision' rifle round is? Normal neck tension (say 2-4 thou, no crimp) no sealant just regular 'match' ammo.

Would it be reasonable to expect the humidity or % moisture content of powder inside a loaded round to remain at, or fairly close to, the ambient conditions at which it was loaded? Assuming that it's just sitting in an ammo box, not physically damaged or exposed to extremes in temperature or moisture ie not left sitting in the sun nor left out freezing or in the rain.

 

[acudaowner]

you could always try it put some powder in a throw away cup put it outside and leave it for a day or two to see first hand what humidity does should also leave bullets out side and try the same experiment and see if they are affected the same way . send video pics and details on how and what you did , what happened or did not happen , an essay no less than 50,000 words soil samples , blood alcohol levels .
bullets are not air proof or moisture proof the between the bullet and the copper case is space granted really tiny space but tiny or not moisture will find a way in . if he is experimenting might as well try it as well just to cover everything . id also suggest setting the case standing up in a tiny bit of water to see if water will get in through the case and primer again really tiny but will it be affected or not .

 

[memilanuk]

I'm going somewhere specific with this, so please, hold off with the wise-assery for a bit. I know it's difficult...

 

[Yondering]

you could always try it put some powder in a throw away cup put it outside and leave it for a day or two to see first hand what humidity does should also leave bullets out side and try the same experiment and see if they are affected the same way . send video pics and details on how and what you did , what happened or did not happen , an essay no less than 50,000 words soil samples , blood alcohol levels .

Why would you see any need to do that with bullets? Lead and copper don't absorb moisture.

 

[NamibHunter]

So... dragging this back onto the original topic...

@mc10 question for you: how well sealed do you think an average 'precision' rifle round is? Normal neck tension (say 2-4 thou, no crimp) no sealant just regular 'match' ammo.

Would it be reasonable to expect the humidity or % moisture content of powder inside a loaded round to remain at, or fairly close to, the ambient conditions at which it was loaded? Assuming that it's just sitting in an ammo box, not physically damaged or exposed to extremes in temperature or moisture ie not left sitting in the sun nor left out freezing or in the rain.

Only way to convince yourself is to run your own experiment. Not hard to do either. Another person’s post will never be convincing…

For what it is worth: Several folks have now run the very simple experiment where loaded ammo is left outside for days or week, to see what happens to the weight of each loaded round, and bullet speed when fired. I have tried it twice, and in both cases, a small minority (5-15%) of the loaded rounds lose or gain between 0.04 and 0.1 gn in weight, which can only be caused by two factors a) absorbing or releasing water vapor due to changes in ambient humidity, or b) off-gassing of volatile chemicals from the powder itself (reducing weight).

Humidity: There is ample evidence, even from the ammo makers themselves, who have published on the topic, that powder humidity affects speed. Powder changes humidity when open to the atmosphere, so don’t leave it in a powder measure hopper, and close the lid tightly. And reload inside the house, not in a shed or a garage.

Evaporation of volatile organic compounds: There is not much known about this effect (at least not in the literature a reloader would encounter), but it fair to assume that the loss of stabilizer chemicals will have some effect on burn rate. No idea how significant or not this is. Or how fast this occurs. [Powder also slowly degrade chemically over time, but this is a very very slow process (many years to several decades). Not under discussion here.]

Whatever the mechanism at work here, a small nr of loaded rounds change weight (and i have confirmed they also change speed). You do need a good milligram scale to pick this up, but if you have one, try it and see for yourself.

The remainder of the ammo appears not to “leak” (or leaks less than 0.02 grains). That inconsistency pushes up the SD by about 1-3 fps (but ES can go way up). Not nothing, but not a train smash either…. You will just shoot over or under your target, maybe 3 to 8x, for one box of 50 reloaded rounds…. For a serious competitor, this will matter. For the rest of us, it is a minor annoyance. [Note that the statistical distribution for MV becomes non-Normal. Two “populations” mixed together, those rounds that leaked and those that did not.]

“Bullet weld” or whatever the correct terms is, is more significant in my testing. It does get a lot worse with time. Load long and reseat the day you go shoot. [Btw: I think wax coated virgin brass is less susceptible to bullet weld, compared to reloaded brass, but i can’t prove that yet.]. To run this experiment, store some loaded ammo for a year or more.

My take-away is to control the humidity of your reloading room: Add a dehumidifier if you live in a humid climate. Add a humidifier if you live in a dry desert climate. Try the humidor trick if you like.

Easy enough to do.

 

[straightshooter1]

Why would you do this?

In the dry desert the dry air sucks moisture out of everything like a dry sponge, doing it rather fast. It not only does it to your body, but it's an issue like with various wood furniture where it'll shrink and crack if not attended to. I've seen my powder loose moisture pretty fast when not put back in it's container as soon as I'm done reloading. And that drying powder DOES burn faster resulting in higher pressures with higher MV's. Even when putting the powder back into it's container, it will have lost enough moister to pull some moisture out of the powder that was left in the container resulting in lower moisture for all the powder in the container as the moister content of the container equalizes. The more extreme the difference between the powder's moisture content to the atmospheric relative humidity the faster the change will take place.

 

[NamibHunter]

Why would you do this?

I live on the Gulf Coast, so i don’t need to do this except for one week a year when Houston drops below 35%, but my contention is that as constant as practically possible humidity in your reloading room is better than seeing 15% on a day with clear blue skies with a wind blowing in from the snowy north, compared to 40% when the wind blows in ocean moisture from the south. I just avoid reloading during this time, but i get nose bleeds if the air dries out too much, so invested in a piezo electric humidifier. Works well for noise bleed prevention. Not sure about powder stabilization…. I run the dehumidifier setpoint at 45%. About 10% below what it was before i bought the 2 machines, one per floor.

My idea is to avoid the situation where the first round you load holds moisture equivalent to 35% (what the bottle was exposed to before you tightly closed it 4 weeks ago), and the last round an hour or two later is closer to 20%, when today’s Relative Humidity is 15% because it is a blue sky day, and the powder is trying to equilibrate to match the ambient conditions. That takes time.

Powder moisture (while sitting in an unsealed hopper) will slowly ramp up (or down) over several hours. Stabilizing the humidity in your reloading room should help to keep the burn rate very similar between the first loaded round, and the last, completed several hours later. [And keep the door closed so you don’t have to adjust humidity for the entire house.]

The published graphs show a very big change in burn rate and speed from that kind of humidity change. So either stabilize humidity in your reloading room by dropping it by 10% (if generally on the high side), or raise it if ambient humidity level is normally on the low side (dry climate). Or simply avoid reloading on days when humidity is abnormal…

 

[straightshooter1]

This is why you stabilize an entire jug of powder. And then it's consistent rather than trying to constantly fight it. Let it dry. It will stabilize at a point. And then you're GTG. Proceed to load

Yeah, that sounds like a good idea for where I live and something I haven't tried yet. Guess, I will do that and see how it goes. However, we're entering monsoon season and when it rains hard the RH can rise from 10% to over 90% and take a few days to subside. Indoor humidity isn't affected as much, but it is substantially effected. So, reloading during those times after drying out the powder will need to be a aware and a little cautious.

 

[Huskydriver]

Just keep it in the jug after initially stabilizing it. It only takes about 72 hours of airing out for your and mine environments.

What are you doing to stabilize it the cooking sheet method or just leaving the lid off?

 

[memilanuk]

Only way to convince yourself is to run your own experiment. Not hard to do either. Another person’s post will never be convincing…

For what it is worth: Several folks have now run the very simple experiment where loaded ammo is left outside for days or week, to see what happens to the weight of each loaded round, and bullet speed when fired. I have tried it twice, and in both cases, a small minority (5-15%) of the loaded rounds lose or gain between 0.04 and 0.1 gn in weight, which can only be caused by two factors a) absorbing or releasing water vapor due to changes in ambient humidity, or b) off-gassing of volatile chemicals from the powder itself (reducing weight).

Whatever the mechanism at work here, a small nr of loaded rounds change weight (and i have confirmed they also change speed). You do need a good milligram scale to pick this up, but if you have one, try it and see for yourself.

The remainder of the ammo appears not to “leak” (or leaks less than 0.02 grains). That inconsistency pushes up the SD by about 1-3 fps (but ES can go way up). Not nothing, but not a train smash either…. You will just shoot over or under your target, maybe 3 to 8x, for one box of 50 reloaded rounds…. For a serious competitor, this will matter. For the rest of us, it is a minor annoyance. [Note that the statistical distribution for MV becomes non-Normal. Two “populations” mixed together, those rounds that leaked and those that did not.]

“Bullet weld” or whatever the correct terms is, is more significant in my testing. It does get a lot worse with time. Load long and reseat the day you go shoot. [Btw: I think wax coated virgin brass is less susceptible to bullet weld, compared to reloaded brass, but i can’t prove that yet.]. To run this experiment, store some loaded ammo for a year or more.

That... actually touches surprisingly closely on what I had in mind when I asked the question. Not so much the leaving the rounds 'outside', if that's what previous testers have done. More so in the context of precision ammo assembled well in advance of a large long-range event, then shipped ahead to a location that has very different temp, BP and RH conditions than where the ammo was originally loaded.

In a few situations I've known of people who insisted that they got better results fine-tuning their loads locally, on-site, than they did bringing or shipping ammo that was pre-loaded from home. The discussion usually went down a theoretical rabbit hole, about whether the rounds were reasonably well sealed to where the conditions inside were the same as what they were at the loading bench, etc. Generally this ammo would be loaded anywhere from a few weeks to a few months in advance, depending on the venue (national vs. international).

I'd generally maintained that the people who were advocating loading on-site were unintentionally skewing the results, because they were usually trying to 'get by' with say, 300 pcs of brass - plenty for a local state or regional 2-3 day match with team stages, etc. Not so much for larger national+ level events that run 4-5 days. When they tried loading 'at the range' with their previous recipe... I'm guessing the local temp/humidity played hobb with their load tune. Their response was something along the lines of "you just wouldn't understand" because I shot F/TR instead of F/Open

I do have some ammo that has been sitting in my air-conditioned (heated/cooled, but not humidity controlled) shop for a couple years. I'd have to look back at my notes to see what exactly the powder charge was originally; it might be interesting to see what it weighs now, on the same scale (FX-120i). I don't *think* I have records detailing the MV average/SD/ES in enough detail that I'd trust it for a representative before/after comparison, though.

 

[MarkyMark007]

dont mix relative humidity and absolute humidity !!!

at 0°C at 100% relative humidity you have as much water in the air (absolute humidity) like at 50% relative humidity at ~18°C.

Air - Maximum Moisture Carrying Capacity

Maximum water content in humid air vs. temperature.

www.engineeringtoolbox.com

when you say that you have 50% relative humidity in some room, at higher temperatures you have a lot more water in the air. and probably you can get more water in the powder at higher absolute humidity; imho...

 

[NamibHunter]

Reviving an old thread:

I see Vihtavouri powders in stock more frequently now, and they claim “extreme temperature stability” and also claim their powder is “insensitive to humidity changes”.

Has anybody done any testing with the N500 series of powders (N560, N565, N568, N570) to determine speed difference between powder at say 30 RH compared to 80% RH? Is it any better than say H4831SC…or Retumbo…

 

[Emerson0311]

Reviving an old thread:

I see Vihtavouri powders in stock more frequently now, and they claim “extreme temperature stability” and also claim their powder is “insensitive to humidity changes”.

Has anybody done any testing with the N500 series of powders (N560, N565, N568, N570) to determine speed difference between powder at say 30 RH compared to 80% RH? Is it any better than say H4831SC…or Retumbo…

Lots of people who aren’t poors have used Vihtavouri powder for years with great success. My experience is just getting started because it was all I could find.

 

[cas6969]

Currently the heat and humidity in my reloading room is keeping me from doing any reloading, so there's that.

 

[MK20]

I spoke to a tech at hodgdon the other day on this subject. He said that the seals on their powder bottles allow exchange of air and humidity but are designed to keep things like rain out should the package of powder sit on your porch after delivery in a rainstorm.

 

[Doom]

First and foremost all of discussion about powder and humidity is fundamentally wrong. Unless I have missed something in my 12 years of reloading, neither Hodgdon (IMR,HXXXX), Alliant, or VV ship their powder hermetically sealed. It isn't necessary. Every container is shipped with a security seal so thet tampering will be evident. As for the container it is most likely HDPE and is essentially non porous. When properly sealed (tightly capped) there is little if any exchange of air between the container and ambient air. If the container breathed, you would not see it bulge out in hot weather and bulge in in cooler weather

AS for the powder itself, it does not have humidity. It does have a moisture content and if left openly exposed to a different environment it will come to equilibrium with that environment. This is a function of mass transfer and occurs, due to the hygroscopic nature of nitrocellulouse, on the surfaces of the powder kernel. Much of the moisture is contained within the kernel and must travel to the surface to be absorbed by the air. Time is required for this transfer to take place. The same is true in reverse, When handling powder most is contained in a packed column, either in the container, in the measure or in the case. Very little air is is directly in contact with the powder and that air tends to stay with the kernel. Also, referencing humidity is an error since the amount of moisture in air is not measured by relative humidity but rather by absolute humidity or humidity ratio. For instance, air at 75F and 60% RH has the same moisture content ratio as air at 60F and 100% RH.

All of the test that I have seen on powder and humidity purposely dry or add moisture to the powder which will always result in a change in mass and burn rate (H2O is a combustion diluent).

An 8 Lb container has a volume of about .3 cubic feet. That is a grand total of .021 lbs of dry air and .0004 lbs of water if the air is 75F and 100% Relative Humidity. A pound of powder would have about 5% moisture, or .05 lbs of water, and if it absorbed all of the moisture from the air, which it wouldn't, it would contain .0504lbs (0.8%) of water. This is a bounding calculation showing the limit of what could happen.

As for powder being shipped with a specific humidity, usually around 60%, this is actually true. It has little to do with moisture content of the powder. It is to prevent the buildup of static electricity in the handling process. This is to prevent explosions.

Unless you live in a Arctic or Desert environment, or leave you powder container open for long periods of time, or put it in the wife's dryer the moisture content of your powder isn't likely to move much.

 

[Doom]

and also claim their powder is “insensitive to humidity changes”.

The 5 series powders are double base containing nitroglycerin which is less hygroscopic than nitrocellulose if memory serves me correctly. So the powder may be be less sensitive.

 

[Doom]

I spoke to a tech at hodgdon the other day on this subject. He said that the seals on their powder bottles allow exchange of air and humidity but are designed to keep things like rain out should the package of powder sit on your porch after delivery in a rainstorm.

Really, rain?

 

[Yondering]

First and foremost all of discussion about powder and humidity is fundamentally wrong. Unless I have missed something in my 12 years of reloading, neither Hodgdon (IMR,HXXXX), Alliant, or VV ship their powder hermetically sealed. It isn't necessary. Every container is shipped with a security seal so thet tampering will be evident. As for the container it is most likely HDPE and is essentially non porous. When properly sealed (tightly capped) there is little if any exchange of air between the container and ambient air. If the container breathed, you would not see it bulge out in hot weather and bulge in in cooler weather

AS for the powder itself, it does not have humidity. It does have a moisture content and if left openly exposed to a different environment it will come to equilibrium with that environment. This is a function of mass transfer and occurs, due to the hygroscopic nature of nitrocellulouse, on the surfaces of the powder kernel. Much of the moisture is contained within the kernel and must travel to the surface to be absorbed by the air. Time is required for this transfer to take place. The same is true in reverse, When handling powder most is contained in a packed column, either in the container, in the measure or in the case. Very little air is is directly in contact with the powder and that air tends to stay with the kernel. Also, referencing humidity is an error since the amount of moisture in air is not measured by relative humidity but rather by absolute humidity or humidity ratio. For instance, air at 75F and 60% RH has the same moisture content ratio as air at 60F and 100% RH.

All of the test that I have seen on powder and humidity purposely dry or add moisture to the powder which will always result in a change in mass and burn rate (H2O is a combustion diluent).

An 8 Lb container has a volume of about .3 cubic feet. That is a grand total of .021 lbs of dry air and .0004 lbs of water if the air is 75F and 100% Relative Humidity. A pound of powder would have about 5% moisture, or .05 lbs of water, and if it absorbed all of the moisture from the air, which it wouldn't, it would contain .0504lbs (0.8%) of water. This is a bounding calculation showing the limit of what could happen.

As for powder being shipped with a specific humidity, usually around 60%, this is actually true. It has little to do with moisture content of the powder. It is to prevent the buildup of static electricity in the handling process. This is to prevent explosions.

Unless you live in a Arctic or Desert environment, or leave you powder container open for long periods of time, or put it in the wife's dryer the moisture content of your powder isn't likely to move much.

"everyone else is wrong" - then proceeds to contradict themselves in multiple places while reiterating many of the same things that were already said by someone else. LOL

And yeah, you've definitely missed something in your incredible 12 whole years of reloading experience. Most powder bottles do breathe with the cap on, and are not tightly sealed. Squeeze them and listen to the air come out, and then suck back in again.

 

[MarkyMark007]

maybe bottles are not the main source of moisture in the powder.

when we make ammo, we expose powder to air in much bigger surface than it is in canister. when we weight it in the pan. I presume that main humidity transfer to the powder is done that way... maybe...

 

[Doom]

This is classic of our population. Reloaders by and large have zero education or real knowledge of chemistry, engineering, or physics. It is the low grade, shade tree, sub-layer of a pretty scientific based industry and we just do a lot of trial and error to develop a load. Load development by nature is just uneducated people formalizing the process of trial and error. I always laugh when people on this site act like they're developing "empirical data". Hell, most people here spell it like "impirical"

You can try to reverse engineer scientific knowledge, talking about relative vs absolute humidity and explain something the rest of us have just plain observed and understood. Or join the rest of us and simply leave some powder out for a week and then load it and shoot it and see what it does. Talk about it in psuedo science. Or just try it out and see the evidence.

This is classic of our population. Reloaders by and large have zero education or real knowledge of chemistry, engineering, or physics. It is the low grade, shade tree, sub-layer of a pretty scientific based industry and we just do a lot of trial and error to develop a load. Load development by nature is just uneducated people formalizing the process of trial and error. I always laugh when people on this site act like they're developing "empirical data". Hell, most people here spell it like "impirical"

You can try to reverse engineer scientific knowledge, talking about relative vs absolute humidity and explain something the rest of us have just plain observed and understood. Or join the rest of us and simply leave some powder out for a week and then load it and shoot it and see what it does. Talk about it in psuedo science. Or just try it out and see the evidence.

You may not agree with what I have said and you are certainly entitled to your opinion but that doesn't make it correct. I will leave it at that.

 

[NamibHunter]

Thought this was interesting: higher humidity makes the powder swell and then a powder measure will be off:




Another good reason for weighing all your charges, and controlling humidity in your reloading room.

 

[NamibHunter]

One of the best write-ups on the topic so far:

How does humidity affect powder?

You may have heard about a relationship between humidity and bullet velocity either in a book, on a reloading forum, or from a crusty benchrest shooter right after saying they get better ES/SD&#821…

chronoplotter.com

 

[NamibHunter]

In my own experiments, some 8 lbs powder bottles leaked and humidity slowly changed (Kestrel Drop left inside recording humidity over a week), but some did not and humidity stabilized in a few hours and then remained constant. I guess it all depends on the damage done to the seal. Maybe the leak rate is just very slow and it will take months to see a change.

The choice of polymer (same as medicine bottles) appears to be air tight.

My worry is if you open a bottle of powder sealed in the factory at 65% relative humidity at 89 deg F and you load a 100 rounds over 2 hours, in winter with RH at 35% and 50 deg F, then the first round will not have the same burn rate as the last one.

Should you pour the powder into a dispenser/powder measure and let it sit for half a day to equilibrate, before you use it?

 

[NamibHunter]

Somebody in a different thread suggested these wi-fi enabled humidity sensors, cheap enough, and small enough to go into a one pound container, so i tried them last week:

Amazon product ASIN B09BVLP9C5
Works remarkable well, and the app is real easy to set up. The 3 humidity Sensors connect to a small wifi base station that remains plugged into a power socket. Your phone then connects to the base station via Bluetooth and download the latest data, once you are in range.

I did not enable the cloud storage. Made in China, but quality looks good, and cheaper than Kestrel ($69 for 3 sensors). Can add more sensors later on.

So these sensors are now inside the three powder containers that i use most frequently, with a two-way Boveda humidity pack in each to keep RH close to 49%, which is about where my reloading room is. The Boveda humidity packs won’t last forever, so this is a way to detect when they are depleted and need to be replaced.

Hopefully this solves the problem where powder humidity changes lead to large changes in muzzle velocity… which can take you out of the node.

 

[Doom]

In my own experiments, some 8 lbs powder bottles leaked and humidity slowly changed (Kestrel Drop left inside recording humidity over a week), but some did not and humidity stabilized in a few hours and then remained constant. I guess it all depends on the damage done to the seal. Maybe the leak rate is just very slow and it will take months to see a change.

The choice of polymer (same as medicine bottles) appears to be air tight.

My worry is if you open a bottle of powder sealed in the factory at 65% relative humidity at 89 deg F and you load a 100 rounds over 2 hours, in winter with RH at 35% and 50 deg F, then the first round will not have the same burn rate as the last one.

Should you pour the powder into a dispenser/powder measure and let it sit for half a day to equilibrate, before you use it?

You worry to much. First your humidity in the jug will change as ambient temperature changes without anything other than dry bulb temperature changing. If you really want to see what is going on look at dew point, not relative humidity. Dewpoint will remain constant for constant moisture content with changing ambient temperature.

 

[NamibHunter]

Humidity pack:

Amazon product ASIN B00JV27MCM
If you live in a desert, then the 32% pack might be more useful to you. If you live on the Gulf Coast and load in an outside shed (no AC), then the 62% packs might be best.

 

[NamibHunter]

You worry to much. First your humidity in the jug will change as ambient temperature changes without anything other than dry bulb temperature changing. If you really want to see what is going on look at dew point, not relative humidity. Dewpoint will remain constant for constant moisture content with changing ambient temperature.

I get what you are staying: RH is a relative measurement, and depends on temperature, and dew point is what matters more. Fair point.

This device monitors temperature as well, and then calculates and trends Dew Point and Vapor Pressure Deficit (VPD). Would be happy to see a fairly constant dew point, when temperature drifts down on cold winter days. Might put a canister outside to see what happens.

Idea is to run an experiment to see if SD comes down post “humidity stabilization project”. We shall see.

 

[straightshooter1]

Let me throw another monkey wrench into the gears.

The issue of leakage. After loads are finished, they can leak moisture unless the cases are sealed with some kind of sealant. If you ever seen how a bag of potato chips expands or contracts with the change in altitude, then you can probably get an idea of what's at work with how a cartridge might leak, in terms of moisture content. So, if you're someone like me loading just a couple hundred feet above sea level then goes hunting at several thousand feet, that difference in pressure can cause cartridges to leak and actually change the moisture content of the powder charge in a loaded cartridge, depending on the difference in humidity/dew-point and the length of exposure at the difference in altitude.

Hmmm??? Is there anything else we can worry about?

 

[NamibHunter]

Let me throw another monkey wrench into the gears.

The issue of leakage. After loads are finished, they can leak moisture unless the cases are sealed with some kind of sealant. If you ever seen how a bag of potato chips expands or contracts with the change in altitude, then you can probably get an idea of what's at work with how a cartridge might leak, in terms of moisture content. So, if you're someone like me loading just a couple hundred feet above sea level then goes hunting at several thousand feet, that difference in pressure can cause cartridges to leak and actually change the moisture content of the powder charge in a loaded cartridge, depending on the difference in humidity/dew-point and the length of exposure at the difference in altitude.

Hmmm??? Is there anything else we can worry about?

You clearly have a lot of reloading experience, and your comments are all valid. My goal is instead of giving up (and living with all these problems), i am more interested in how to resolve them. So very open to fresh ideas.

Yes, loaded rounds exchange air with ambient once there is a pressure differential, either because a low pressure/high pressure system moved in, or you took your ammo on a plane to a match. Have seen this happen over a 3 month period by weighing loaded rounds on a milligram scale, posted some results elsewhere on this site. Effect is very real. Tried sealing the cases (using the Ranger industrial sealant), that stopped the weight changes on 90% of the loaded rounds, but the variable amount of “glue” in the neck changed the neck tension and did more harm than good to the SD of the batch. So a failed experiment. If you know of a better solution, i would be curious.

Not trying to “worry”, not trying to scare anyone, just trying to identify what problem is keeping my SDs at 7-9, and what to do to get it to 4-5 fps….

Btw: Bullet weld was the major issue for me, caused my SDs to start off at 12-14 fps, and mostly got that resolved: Tumble in walnut media with 2 teaspoons of mineral spirits plus a tiny amount of polymer car wax mixed in, for 2 hours only controlled via a timer (don’t over clean the inside of the necks), use Neolube nr 2 on the inside of the neck, seat long, reseat the morning of a shoot. That took my SD from 12 to 8. So on to the next problem.

Looking for ideas to get to 4, and what experiments to run, not trying to tell anybody what to do…. Humidity control looked like a viable candidate.