Whats is optimum climate for long term gun/ammo storage?

Lower humidity is definitely better. Fluctuating temperatures are also a problem. I always thought an old chest freezer would be good for ammo storage. They’re fairly air tight, so once you get the humidity out it would probably be slow to get back in. I like desiccant for drying the air over heat rods.

From what I’ve read over the years, 50-60 % humidity is ideal. If your humidity gets too low, wood can dry out and crack; also rubber and silicone will dry out quicker as well.

As far as what is Too low (?), I don’t know. For me, I wouldn’t want to go below 40%. But then, I have a lot of wood stocked guns.



Edit to add: this post related to guns, I wasn’t considering Ammo.

40% relative is plenty low. 72 is getting up there. The rods are constant , keep using them. (inside a safe?) It is worth trying desiccants in an effort to take the edge off of the humidity spikes to mentioned , but do not eliminate the rods.
So far no one has brought up the obvious - are you using an electric dehumidifier? If not , do so. 2 if necessary. It won't be beneficial to your utility bill , but they work.

It would be good to lower the high end of that fluctuation , but I would not say that you are deep in the danger zone. If ammo brass stays fairly bright and clean you are fine. If it turns dull with green in the recesses you have significant trouble.

Let your brass and steel be your indicators.

40 to 50% will work just fine. Sealing ammo in an airtight container is OK IF the air you trap in the can is below 45% when you seal it up. If you trap moist air in the can corrosion will happen.

move to arizona!

murf

Having spent most of my life living within walking distance of the high Tide mark ( including living on boats, and one apartment where spring and fall high tides came up to the garage) I can definitely say that getting rid of the cardboard is a really good idea.

In my mind and my practice, regardless of storage conditions, there is no substitute for the insurance of a quick visual inspection (say) once a month (same as oil, tire pressure, etc with a vehicle) - very cheap insurance.

Agree with Ramone, get rid of the card board boxes they come in. Most of my ammo is loose in ammo boxes with a seal also use these water tight storage bins.
https://www.amazon.com/IRIS-Quart-W...torage+bin&qid=1601216262&sr=8-13&tag=mh0b-20

I put 4 or 5 of the little desiccant packs in 50 cal ammo cans when I close them up. I don't think less humidity is an issue for storing ammo. For long term storage of firearms, I'd consider taking stocks off of things, and vacuum sealing them if they are wood, and slathering the metal in gun grease inside and out.

If your humidity is going high to low in a day like that, you may have too much air circulation going through, seems like a huge swing. In my area in the Northeast, humidity can spike way up outside at times in the summer, and sweat will just drip off you if you go outside. I just run an AC in the same space as my gun cabinet, and it pulls the humidity out of the air - and keeps the temp around 70.

I don't like or need to use anything that adds heat, dehumidifiers and golden rods add heat - and heat is one of the variables in the equation of heat and humidity in firearms storage. I run several large canisters of the desiccant packs, 4 or 5 in my gun cabinet. Humidity is usually 55% and temp is mostly around 70 as the temp is controlled by the living space temperature. When the humidity starts to creep up toward 60%, I recharge all the canisters.

Defunct freezer is an excellent storage point. Not out of place to see them with a hasp and lock on them, either.

It's important to remember that all of the "rods" are just tiny heaters. The principle is very simple--warmer air cannot "carry" as much water vapor ("humidity") as cooler air.
Here is the classic chart:

If we look at 70º (dry bulb) and move up the line, the dew point (wet bulb) temperature needs to be about 60º for a 50% Relative Humidity.
Warming the air to 75º and go up that like, now the dewpoint has moved up to 65º for 50% RH.
So, It's Science! []
But, there are limits.
At higher RH, you may not be able to heat the air enough to lower the humidity within the heating range of a given rod (most rods are expected to work at basement like temps--65-75º and similar humidities).
A wet place like the PNW you might need 10, 15, 20º of heat, and, having pushed past the dew point, you will be condensing moisture out of the air.

The tl;dr answer to OP is something around 60-65ºF at less than 50% RH would be an ideal storage situation, with limited direct sunlight.

CapnMac said:

Defunct freezer is an excellent storage point. Not out of place to see them with a hasp and lock on them, either.

It's important to remember that all of the "rods" are just tiny heaters. The principle is very simple--warmer air cannot "carry" as much water vapor ("humidity") as cooler air.
Here is the classic chart:
View attachment 945280
If we look at 70º (dry bulb) and move up the line, the dew point (wet bulb) temperature needs to be about 60º for a 50% Relative Humidity.
Warming the air to 75º and go up that like, now the dewpoint has moved up to 65º for 50% RH.
So, It's Science! []
But, there are limits.
At higher RH, you may not be able to heat the air enough to lower the humidity within the heating range of a given rod (most rods are expected to work at basement like temps--65-75º and similar humidities).
A wet place like the PNW you might need 10, 15, 20º of heat, and, having pushed past the dew point, you will be condensing moisture out of the air.

The tl;dr answer to OP is something around 60-65ºF at less than 50% RH would be an ideal storage situation, with limited direct sunlight.

Click to expand...

Actually, warm air carries more moisture than cool air, which is why you get condensation as the temperature drops. The air can no longer hold as much moisture so it starts condensing on surfaces. Heating the air keeps the moisture in the air, but doesn’t remove the moisture. This is why I prefer desiccants for humidity removal over a heating rod. If that rod fails for any reason, your relative humidity is going to climb as the temperature drops. A cool, stable temperature with low humidity is going to be the best option.

An option for a cheap desiccant is white rice. I was just reading a couple studies that showed it removed moisture from hearing aids as effectively as some commercial desiccants.

Museums prefer 50% humidity to keep their relics in pristine conditions; 40% is just fine. Use some box desiccants with your golden rod

I've left boxes of ammo in my truck for years through brutal summers here in the swamp with very high relative humidity and they fired fine. even longer in a garage with very high rh and high temperatures. not saying to do that, but dont over think it all for perfection.

I just store all mine in US GI issue ammo cans. If the can is in good shape, you're good to go. I just opened one I got from my granddad that full on 30 M1 carbine ammo. He sealed it in the 70s. The stuff is just fine. It was stored in his unheated barn for 10 years, then in my unheated garage for another ten. Then my dampish basement.