Humidity Effects on Smokeless Powder
00:49:40 | In this episode, Bryan and Francis discuss Chapter 7 of Modern Advancements in Long Range Shooting – Volume 3, which covers the effects of humidity on smokeless rifle powder. We discuss the problem of powder absorbing and losing humidity and how this affects hand loaders and traveling and handling ammunition. Some simple solutions are discussed which will enable you to ensure more consistency with your ammunition.
Why does thia not have any audio it shows 0:00 -0:00
I can get 1sr 5 min if im not logged in but 0min when logged in
I apologize for the audio issue. I believe it is now fixed.
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Have a Kestrel D2 in an half consumed 8lb jug. Not sure what it was when I got it. I’m using a psychrometric chart to map specific (absolute) humidity. Not sure how “sealed” my container is but I would assume that fewer pressure (diff) fluctuations would lead to more stable conditions inside (slower equil)
Has applied ballistics studied the effects of powder humidity on the temperature sensitivity of a powder?
For example, powder X is humidity controlled and produces a 1 fps per degree of temperature change muzzle velocity.
The same powder X with low humidity produces a 0.7 fps per degree muzzle velocity temperature sensitivity.
And the same powder X with a high humidity becomes less temperature stable resulting in 1.3 fps per degree muzzle velocity variation?
It seems to me that this may be a reason to choose a specific humidity for your powder. Some may want to increase humidity or decrease humidity of thier powder in order to achieve a lower ES due to temperature variation.
Obviously maintaining a consistent humidity is one step in achieving low ES and SD values.
However, if a certain humidity level makes a powder less or more sensitive to temperature variation, it seems a fella might be able to choose a humidity level that achieves a more consistent muzzle velocity through all temperature ranges.
The testing would have to include several powders, each having a high humidity and a low humidity powder.
Each combination would have to be tested in hot and cold temperatures with a large enough sample size to see the effect of humidity on temperature sensitivity.
I live out in the western mountain desert.
It’s a low humidity environment that expiriences large temperature swings in the same 24 hour period.
After listening to this podcast, I assume my powder is constantly drying out as compared to factory conditions.
Realizing that it only matters that the humidity stays consistent in order to produce consistent SDs, I began to wonder if I am going to start to control my humidity, is one end of the humidity spectrum better or worse? The only factor I could come up with that might cause me to choose high or low humidity storage might be temperature sensitivity.
Because it seems to me that a high humidity might make powder more sensitive to cold or hot temperatures, resulting in an increase or decrease in muzzle velocity from the point of load development and testing to actual use.
That is an interesting point Michael! I don’t think we’ve looked into that way but I will make a note of that for future testing.
One thing they forgot to mention is which RH bóveda pack to get
If you are using Hodgdon powders, use a 49% pack, if you are shooting VV use a 58%. With that said, if you have a kestrel drop and can measure humidity then you can open a new jug of powder and throw one in, watch it for a couple of days and then buy the pack that most closely matches the factory state of the powder.
Why different RH levels for different powder manufacturers?
If I live and shoot in an area that hangs around 30-40%RH would it not be better for me to open my powder bottles and let them “dry” out before I load my rounds? My thought was to put some 32% packs in them. Seems like having the powder on the drier side would be better especially if you live in a dry climate. Is there a disadvantage to keeping powder drier than when it was produced?
Seems like matching the powder RH to the environment you plan to shoot will give you more consistent results.
I’ve seen the comment about if you’re using Vihtavuori Powder you should use 58% bovida packs and use the kestrel drop to monitor the powder by Mitch. I’m all good with that part but my next question is, how do u determine what size bovida pack should you get for a 8 lb jug of powder? Bovida has 5 different sizes for the 58% packs. I heard motion in the pod cast of a hand sized pack being used for an 8lb jug. Obviously with a small amounts of powder (1 lb jug) you would use a smaller pack due to the size of the container. Can you use the smaller packs( size 8 ) in a 8 lb jug or does it “ work better “ if you use the larger packs ( size 67 or size 320 )?
This is very good discussion on a topic that most shooters overlook. What about primers? I am surprised that their packaging is open to the air.
I am hesitant to put a Kestral drop inside a powder container since it contains a lithium battery energy source. What is the rationale for deciding this is a safe thing to do? I doubt the drop is designed to be intrinsically safe or explosion proof.
Testing for humidity and controlling humidity are two different practices. Most individuals should focus on management of powder RH (rather than measurement) by simply using Boveda or RH control pouches to keep humidity to managed level. Most powders range from 45-60% RH so simply selecting a specific RH range to target and keeping it in that range is the correct approach.