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How does humidity affect powder? A new experiment

NamibHunter said:
You clearly have a log of reloading experience, and your comments are all valid, but my attitude is instead of giving up and living with all these issues, 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.
Click to expand...
If I were flying, I'd have my cartridges in a sealed container that can withstand the pressure difference. And, in the container I'd have the appropriate humidity control pack. Then I wouldn't take the cartridges out of the container until I was ready to use them. Leakage isn't instantaneous and neither is the transfer of moisture. So, the time from removing the cartridges from a climate controlled container to chambering and firing, shouldn't amount to much of a factor.

For hunting, some kind of sealant would be best; something like some manufactures use on some of their ammo. Wish I knew what that is.

NamibHunter said:
Not trying to “worry”, not trying to scare anyone, just trying to identify what keeps 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 variance looked like a viable candidate.
Click to expand...

Agree, about not cleaning the inside of the necks. After annealing and cleaning the outside of the necks with steel wool, I like to tumble with white rice (medium grain) after I've sized them having used Imperial Sizing Die Wax. The rice absorbs the wax lube and apparently leaves a very thin coating on the inside of the neck, which makes for nice and consistent seating and no bullet weld; at least, no detectable weld in a 6 month period that I've experienced. The outside of the cases are cleaned nicely, though not what one can get with wet tumbling, but that's not my goal anyway. Here's what my cases look like after 5 firings using this method:

6.5 PRC Lapua Brass.JPG
 
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NamibHunter said:
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.
Click to expand...

On bullet weld - I’ve been experimenting with a method of coating the case necks in wax (on the inside) to prevent this. Letting some ammo sit now to see if it welds or not.

The other thing I do currently is to rinse my sized cases in laquer thinner, saving and reusing the solvent so that it contains enough case lube to leave a thin and consistent film in the case necks. This has shown me benefits in consistent seating force and reduced likelihood of cold welding.
 
Thanks for the ideas, it is much appreciated.

Guess a small Pelican pistol case would work to prevent a pressure change affecting the water content of the loaded rounds (and therefore burn rate and MV) when flying.

Pelican cases, like many others, have a pressure relief valve, so at least you can equalize pressure before opening it, once you arrive in say Denver Colorado, or Tajikistan - for a once in a lifetime Marco Polo sheep hunt, that will cost you at least $50K. 😊

Will will try the rice tumbling media. I know Greg Dykstra of Primal Rights is a strong proponent as well.

I seal my hunting ammo with Ranger Industrial Sealant (multiple colors are available), which is advertised as suitable for sealing primer and bullet. Hornady used to sell a primer sealant, but it was discontinued. Both worked fine to keep water out, but they have their own downsides too (increased and variable seating force, if you try to seat the bullets deeper before firing). That was not a good sign.

Found it easy to seal the primers, but rather tricky to properly seal the bullets. Some cases still leaked and changed weight by almost 0.1 grain over 3 months, and perhaps 10% of the cases ended up not properly sealed. [Best theory i could come up with: Old cases often have deep scratches on the inside, and i guess the sealant is seeping deep into the neck, and some cases have more or deeper scratches than others…. But who really knows!]

 
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MarkyMark007 said:
looks like another problem in the making, and industry is already selling products for non-existent problem...
Click to expand...

There's a big difference between a problem you didn't know about, and a problem that doesn't exist. I'm not sure which one you're referring to here, but both humidity and cold welding are known and documented concerns that do affect internal ballistics. You either not knowing about them, or not shooting at a level that shows their influence, does not mean they are a non-existent problem.

Plenty of uneducated people drive their cars around without having the oil changed, but that doesn't mean engine oil life is a non-existent problem. It just means those people are ignorant.
 
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I did a very small test just to calm down my curiosity
I have a 8LBs keg of H4350 that has about 4lbs left with %42 RH and I am getting consistent Results
I bought a new 1lb bottle just to see how diffrent the velocity is going to be?!
I put my kestrel D3 in the bottle and waited to get a stabilized number, was about %49-50
I put a %49 Boveda pack and waited another day knowing it will go up to %53(did it before)
I loaded 5 rounds each from the old jug and the new bottle
41.3grs
Lapua SRP
CCI 450
Berger 144 LRHT
Barrel was clean so I shot 8 fouling rounds and waited for the barrel to cool down to 80-90 and shot the 5shot group
Here is the velocity report
Groups are in different day with very close temperatures

%53 RH

IMG_0531.png


%42 RH

IMG_0532.png


I knew where my nodes where with the 8pounder keg

So I shot another ladder from 41.2 to 41.6 with 0.1gr increment 5 shots each

I noticed with %10 different in RH I am still getting consistent results with my load at 41.3grs and the average velocity changes only about 2fps.
The brass was preped the same day for both tests, was sorted for accurate shoulder bump and neck tension
I know 5shots doesn’t seems very statistical insignificant to come to a conclusion but now I know how consistent are Hodgon extreme powders and I don’t need to sweat over %10 RH as long as I keep my powder sealed, maybe I need to adjust the powder charge by 0.1grs.

Average 5shots velocity (%42RH)
41.1grs 2780fps SD: 5.0
41.2grs 2794fps SD:3.8
41.3grs 2797fps SD:1.4
41.4grs 2799fps SD:5.8
41.5grs 2807fps SD:2.7
41.6grs 2812fps SD:3.5


Average 5shots velocity (%53RH)
41.2grs 2788fps SD:7.0
41.3grs 2797fps SD:3.5
41.4grs 2801fps SD:4.8
41.5grs 2806fps SD:2.7
41.6grs 2816fps SD:1.5
 
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Max_The_Phoenix said:
I did a very small test just to calm down my curiosity
I have a 8LBs keg of H4350 that has about 4lbs left with %42 RH and I am getting consistent Results
I bought a new 1lb bottle just to see how diffrent the velocity is going to be?!
I put my kestrel D3 in the bottle and waited to get a stabilized number, was about %49-50
I put a %49 Boveda pack and waited another day knowing it will go up to %53(did it before)
I loaded 5 rounds each from the old jug and the new bottle
41.3grs
Lapua SRP
CCI 450
Berger 144 LRHT
Barrel was clean so I shot 8 fouling rounds and waited for the barrel to cool down to 80-90 and shot the 5shot group
Here is the velocity report
Groups are in different day with very close temperatures

%53 RH

View attachment 8288843

%42 RH

View attachment 8288844

I knew where my nodes where with the 8pounder keg

So I shot another ladder from 41.2 to 41.6 with 0.1gr increment 5 shots each

I noticed with %10 different in RH I am still getting consistent results with my load at 41.3grs and the average velocity changes only about 2fps.
The brass was preped the same day for both tests, was sorted for accurate shoulder bump and neck tension
I know 5shots doesn’t seems very statistical insignificant to come to a conclusion but now I know how consistent are Hodgon extreme powders and I don’t need to sweat over %10 RH as long as I keep my powder sealed, maybe I need to adjust the powder charge by 0.1grs.

Average 5shots velocity (%42RH)
41.1grs 2780fps SD: 5.0
41.2grs 2794fps SD:3.8
41.3grs 2797fps SD:1.4
41.4grs 2799fps SD:5.8
41.5grs 2807fps SD:2.7
41.6grs 2812fps SD:3.5


Average 5shots velocity (%53RH)
41.2grs 2788fps SD:7.0
41.3grs 2797fps SD:3.5
41.4grs 2801fps SD:4.8
41.5grs 2806fps SD:2.7
41.6grs 2816fps SD:1.5
Click to expand...

Though "5shots doesn’t seems very statistical insignificant to come to a conclusion", it really isn't significant enough to draw any kind of conclusion. One could get the very same difference, or even more, between 2 different 5 shots using the same lot of powder. Though, you do have 5 different 5-shot groups to compare that would seem telling enough that for most shooting disciplines, that humidity difference makes no difference on target. IMHO, this would have been more telling had you done 25 shots with just one powder load from each. 🤷‍♂️ :giggle:
 
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Industrial laboratories have very tight standardized controls on the temp and humidity.

The vast majority of us don't have the resources to put that kind of expensive controls on our home workshops, so the best we can do is try to keep things reasonable, pick conditions that are reasonable, and learn to watch and record them. It is a long term learning feedback loop.

The sooner a rookie learns that climate is important at the range as well as in the workshop, the better. YMMV
 
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straightshooter1 said:
Though "5shots doesn’t seems very statistical insignificant to come to a conclusion", it really isn't significant enough to draw any kind of conclusion. On could get the very save difference, or even more, between 2 different 5 shots using the same lot of powder. Though, you do have 5 different 5-shot groups to compare that would seem telling enough that for most shooting disciplines, that humidity difference makes no difference on target. IMHO, this would have been more telling had done 25 shots with just one powder load from each. 🤷‍♂️ :giggle:
Click to expand...
I literally had the same point of impact in both tests
Group size pretty close
%53 RH target
From left to right 41.2 to 41.6
IMG_0533.jpeg


%42 target

From left to right
41.2 to 41.5
41.6 to 41.9
C1734FA3-0896-441B-BA4D-4F3CBF8749EA.jpeg
 
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whatsupdoc said:
Hodgon 8lb jugs are crap, the mouth lip is kind of ragged and many times the "seal" is not properly bonded to
the container mouth. The container is made from HDPE so it has good moisture barrier properties
but is a poor oxygen barrier.
Not sure if oxygen is detrimental to smokeless powder but I would think long term it is.


From the VihtaVuori Web Site:

----------------------------------------------------------------------------------------------​

Did you know? Powder moist content​

18.07.2018

Variations in moisture content change the burning rate of a powder and thereby chamber pressures and muzzle velocity. The moisture content of the N100 and N300 series powders is usually around 1 %, the N500-series’ normal moisture content is 0.6 % because of the added nitroglycerine.
So what difference does moisture content have? Here’s an example. In a test, a powder sample was dried by heating it, losing about 0.5 % of its weight. Cartridges were then loaded with the dried powder and fired using a pressure gun. Chamber pressures and muzzle velocities produced by these special cartridges were compared to those produced by cartridges loaded with untreated powder. (The powder charge and bullet were of course the same in both sets of cartridges.)
Comparing results showed chamber pressures increased from 320 MPa to 355 MPa with the dried powder, and the muzzle velocity increased accordingly from 770 m/s to 790 m/s (2526 to 2592 fps). And note, this is only one example, of one caliber and loading. The difference might be much higher depending on the cartridge and loading combinations.
What does this tell us? Well, it seems we need to forget the o
Click to expand...

whatsupdoc said:
ld saying “Keep your powder dry”! Instead, focus on proper powder storage, at a temperature below 20°C / 68°F and humidity between 55-65 %. Safe reloading everybody!
---------------------------------------------------------------------------------------------------------------------

Their powder has a moisture content of .06% to 1% so this leads me to believe that most smokeless powder will fall
somewhere close to that range.

So am I understanding that 55-65% humidity will keep the moisture content between the .06% to 1% range.
Click to expand...

This is kind of interesting... so the implication may be that the moisture content lowers/raises the 'weight' of the powder. Not necessarily the combustion rate or chemical 'composition?'

So more humidity = more water content = powder is heavier for the amount of 'chemical content' so in essence you are throwing 'lighter charge weights?' Is that what I somewhat gather?

This is a very fascinating topic. Thanks OP for the initial post (c. 2021). I have more reading to do now that I've gone down this rabbit hole. Can't believe I missed this thread when it started!

Never really worried about humidity because I load large lots of ammo at a time. Never less than 500 at a sitting for .308 or .300. For higher-end stuff like .338 or .50 at least 200 at a time. Then check zero/DOPE, etc. And ammo is stored in tight cans.

But this is pretty interesting stuff. Time to put a Humidity gauge in my loading room because it definitely swings to very, very low humidity in winter. And much higher in summer. So this matters!

Back to reading...

Cheers,

Sirhr
 
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And to be clear to summarize the above, and all the other posts on the matter:

As the powder dries out, it gets lighter so you put in more mass of powder to achieve a given charge weight say, 40 grains. If you put in wet powder into a 40 grain charge, perhaps only 39.5 grains of it would be powder and the rest water.

Furthermore, that water saturated powder burns, slower, achieving less pressure and less velocity.

So if you opened a new keg of powder and went up to a max load of, let’s say 42 grains, but then your powdered dried out over the course of the summer, and you loaded up more with the same powder at 42 grains you would easily be over max

And that’s not even accounting the effective temperature. Supposing the powder in question is temperature sensitive and you developed a max load in March. And then your powdered dried out through the month of August when you loaded the same load and shot it at 90° instead of it 30°. Now the effects of the aforementioned have increased and you are way over pressure.
 
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