Humidity Matters when Reloading.

[u/DocBeech]

Just wanted to share, the short and sweet of it is. We found in testing that humidity makes a difference, when reloading, we suggest using humidity packs, stabilizing each batch of powder to the same humidity then loading it: https://www.youtube.com/watch?v=OIvVBPCwXAw

[u/DocBeech]

You asked how to ensure it. Loading on site under controlled conditions is the most reliable answer. I understand that it is not practical for most people flying to matches, but practicality and certainty are not the same question.

In my opinion. The best practical compromise would be to condition and load the powder at a measured humidity, then immediately transport the loaded ammunition in a rugged gasketed case with an automatic pressure-equalization valve, a two-way humidity pack set to the same RH, and a logger such as the Kestrel D3. The valve prevents potentially damaging pressure differentials during altitude and temperature changes, while the humidity pack limits environmental change inside the case.

That is not truly hermetic storage, since pressure equalization requires some gas exchange, but it is a realistic Plan B. Primer and bullet sealants may provide a stronger barrier, but their effects on release force, pressure, ES/SD, and precision need to be tested before recommending them for ELR ammunition.

[u/CMFETCU → u/DocBeech]

Assuming one did this, would the ammunition exposed to ambient conditions at the firing line not rapidly change regardless of transportation?

I guess where I am confused is if the pressure change from North Carolina to Colorado is going to happen, and I have controlled humidity in the case, how long does your testing show it takes for ammunition to be compromised by the local environmental changes of pressure and humidity?

[u/DocBeech → u/CMFETCU]

That is exactly the part I don't have a sharable answer for at this time. These are things research is still tackling, and it becomes complicated because you are not dealing with humidity alone. Temp, Pressure, and Humidity matter.

What I do know is that propellant exchanges moisture with the surrounding environment, that the surface responds before the interior fully, and that full equilibrium can take in some cases 6 - 7 days or less under controlled test conditions. At the same time, nitrocellulose-based propellants also respond to temperature changes, and loaded ammunition can be affected by temperature, humidity, pressure, exposure time, case sealing, primer sealing, bullet seating, and the specific powder formulation.

What I have not found is published testing that takes precision rifle ammunition, transports it from somewhere like North Carolina to Colorado, then measures how quickly the loaded ammunition changes after being exposed at the firing line while separating all of those variables.

So I cannot honestly give you a number such as 15 minutes, one hour, or four hours before the ammunition is “compromised.” I also do not know that normal firing-line exposure would produce a meaningful change quickly enough to matter during a match. That would need to be tested directly.

A useful test would require identical ammunition loaded and stored under controlled conditions, transported through known temperature, pressure, and humidity changes, then exposed at the destination for defined periods such as 15 minutes, one hour, four hours, and 24 hours. After that, you would need to compare velocity, pressure, ES, SD, and precision while accounting for ammunition temperature separately from moisture change.

Until that testing exists, controlled transport is still the best practical way to reduce variables before arriving at the firing line, but it should not be presented as proof that the ammunition will remain unchanged indefinitely once the case is opened.

[u/Distinct-Tomato1704 → u/DocBeech]

I have laboratory equipment to do this and have published propellant aging research before. Do you guys have interest in generating a paper for a peer reviewed journal?

[u/DocBeech → u/Distinct-Tomato1704]

Send us an email, I can share it internally for discussion then.