Conditions that can change component consistency

Rodney65 · Feb 1, 2025

Is there any storage, environmental, or similar conditions you guys have observed or tested and discovered that can cause a change in reloading components or accelerate/decelerate a change?

Just wondering about things like storing primers in sealed bags with oxygen absorbers versus just in their factory boxes, powder being left in a hopper (does it matter if your reloading room is dark?), component age (some people say they use the same jug of powder for years), humidity in reloading room, or cold/warm cycles in storage.

Sometimes I will get a velocity change with the same components and I can not identify the cause. I actually had some ammo chrono faster on a cold day and it made me think my chrono was off.

Interested in thoughts, opinions, personal or professional tests.

Rodney65 · Feb 1, 2025

Oh sorry as soon as I posted the thread I saw this come up which addresses a lot of what I was wondering:

Advanced musings on powder humidity

I've been using humidity packs in my powder for about 2 years. Was at range the other day, shooting 50 BMG reloads, 2865 fps, SD

www.snipershide.com

RegionRat · Feb 1, 2025

Rodney65 said:
Just wondering about things like storing primers in sealed bags with oxygen absorbers versus just in their factory boxes, powder being left in a hopper (does it matter if your reloading room is dark?), component age (some people say they use the same jug of powder for years), humidity in reloading room, or cold/warm cycles in storage.

Sometimes I will get a velocity change with the same components and I can not identify the cause. I actually had some ammo chrono faster on a cold day and it made me think my chrono was off.

KISS

Ammo, primers, and powders (the kinds we discuss on this forum) are not intended to be stored in conditions other than standard breathing air, so no absorbers of any kind, no vacuum, no dry gas, no desiccants, etc.

The closer you keep storage conditions near 68F 50% RH, the longer it will last.

Good olde MIL-Spec GI ammo cans closed on normal conditions will protect ammo.

Barrier film bagging heat welded to create a water-proof seal will also work but barrier film bagging is not the same as polyethylene. It has trade names like Aclar.

Primers should be kept in OEM packaging and stored where there is low risk of impact, drops, shock, water, or chemical contamination.

Heat sealed Aclar bags will protect ammo and primers even in floods. Powders should also be kept well sealed in the OEM plastic jugs.

Rodney65 · Feb 1, 2025

RegionRat said:
KISS

Ammo, primers, and powders (the kinds we discuss on this forum) are not intended to be stored in conditions other than standard breathing air, so no absorbers of any kind, no vacuum, no dry gas, no desiccants, etc.

The closer you keep storage conditions near 68F 50% RH, the longer it will last.

Good olde MIL-Spec GI ammo cans closed on normal conditions will protect ammo.

Barrier film bagging heat welded to create a water-proof seal will also work but barrier film bagging is not the same as polyethylene. It has trade names like Aclar.

Primers should be kept in OEM packaging and stored where there is low risk of impact, drops, shock, water, or chemical contamination.

Heat sealed Aclar bags will protect ammo and primers even in floods. Powders should also be kept well sealed in the OEM plastic jugs.

Thanks for the reply.

I usually throw a few desiccant packs in the storage totes containing my sleeves of primers. I do have a vacuum sealer so maybe that would be the way to go.

I had heard the advice you gave about powder before, don't add the packs, but then in the thread I linked to people are transferring them to jars and mucking with the humidity.

Doom · Feb 2, 2025

Primers are pretty much inert so as long as they don't get wet or come into contact with oil they should be fine in there original. packaging. Temperature above 135F can be bad for them. You can go down the powder humidity rabbit hole but if you keep your powder properly closed in its original container you are not likely to see a discernible change in its properties. Putting humidity packs in a jug and not controlling the temperature it resides in actually causes the powder to change its moisture level continuously. There is one thing that is often missed and that is actual storage of cases. Brass is subject to several forms of corrosion which can ultimately lead to case failures. Ammonia, chlorine and several other chemicals in the environment can lead to failure. High humidity environments should be avoided as well as areas where ammonia or urea vapors may be present, even in trace amounts. While a common practice wet tumbling with tap water exposes brass to unknown chemicals including chlorine which may shorten the life of the case due to dezincification or stress corrosion cracking.

The advice that @RegionRat has given is in accordance with what powder and primer manufacturers recommend.

Rodney65 · Feb 2, 2025

Doom said:
Primers are pretty much inert so as long as they don't get wet or come into contact with oil they should be fine in there original. packaging. Temperature above 135F can be bad for them. You can go down the powder humidity rabbit hole but if you keep your powder properly closed in its original container you are not likely to see a discernible change in its properties. Putting humidity packs in a jug and not controlling the temperature it resides in actually causes the powder to change its moisture level continuously. There is one thing that is often missed and that is actual storage of cases. Brass is subject to several forms of corrosion which can ultimately lead to case failures. Ammonia, chlorine and several other chemicals in the environment can lead to failure. High humidity environments should be avoided as well as areas where ammonia or urea vapors may be present, even in trace amounts. While a common practice wet tumbling with tap water exposes brass to unknown chemicals including chlorine which may shorten the life of the case due to dezincification or stress corrosion cracking.

The advice that @RegionRat has given is in accordance with what powder and primer manufacturers recommend.

All good to know, thanks.

I was a bit curious about primers as their packaging does not seem to be moisture resistant in any way just being paper sleeves in paper boxes.

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