Reloading shop temp

AWS

Custom Accessory Maker & Retired PM Staff
What would be the highest temp acceptable for a dedicated reloading room. I have mine in the back of the attached garage. I used to have a swamp cooler and could leave the garage to kitchen door open and vent it out the shop window and cool the whole garage. Last year we put in refrigerated air so.no circulation through the garage and shop. I put a remote temp.sensor in the shop and the shop is holding at a pretty steady 85⁰ at shoulder height. It is warm up but still reasonable to work in. Other than the powder I'm working with powder is stored in insulated coolers in the concrete floor..


Thanks

AWS
 
Very good question, Erich. I was surprised at the AI answer:

Ammunition should never be stored above 150°F (66°C); SAAMI and multiple industry sources identify 150°F as the upper safety limit, with ideal storage kept between about 55–85°F. Prolonged exposure above this threshold accelerates propellant and primer degradation, increasing risks of misfires, squib loads, and case failures.​

Recommended Storage Temperatures​

  • Ideal range: 55–70°F (13–21°C). kikofirearms.comkikofirearms.com
  • Acceptable general range: 60–75°F (15–24°C). TheGunZoneTheGunZone
  • Absolute maximum: 150°F (66°C). Ammunition begins chemical breakdown near this point. TheGunZoneTheGunZone+1
  • SAAMI guidance: Keep ammunition between 55–85°F for best longevity. tactibeaver.comtactibeaver.com

Why 150°F Is the Critical Limit​

  • Propellant degradation: Nitrocellulose-based powders begin off‑gassing and breaking down around 125–150°F. kikofirearms.comkikofirearms.com
  • Primer weakening: Priming compounds degrade above ~140°F, causing misfires. kikofirearms.comkikofirearms.com
  • Case integrity: Repeated heating cycles can make brass brittle and prone to cracking. TheGunZoneTheGunZone

Practical Storage Guidelines​

  • Store ammunition in a cool, dry, dark place.
  • Maintain humidity below 50%, ideally 30–50%. kikofirearms.comkikofirearms.com+1
  • Avoid attics, vehicles, or garages where temperatures can exceed safe limits.
  • Use sealed ammo cans with intact gaskets to reduce moisture exposure.

Summary​

Ammunition remains safe and reliable when stored below 150°F, with best results in the 55–85°F range and controlled humidity.
 
I would imagine the components, no matter what they're stored in, will eventually reach ambient temperature.

You mentioned a window in the garage, I would get a window or portable air conditioner.
 
I have never seen single digit humidity :ROFLMAO:. Don't know if ever below 40-50% except inside in the winter if a house doesn't have a humidifier on the furnace.
One of the only perks of living where i do. The other is only needing a light jacket or sweatshirt in the dead of winter so long as the wind isn't blowing.
Drawbacks are less than 12" of precipitation a year and temps up to 120f at the hight of summer.
 
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Humidity is an issue when wanting to duplicate charge weights from previous reloading sessions. I use a dehumidifier to maintain 50% in basement in the summer. Winter no issues with humidity exceeding 55%.
 
One of the only perks of living where i do. The other is only needing a light jacket or sweatshirt in the dead of winter so long as the wind isn't blowing.
Drawbacks are less than 12" of precipitation a year and temps up to 120f at the hight of summer.
Where is that?
Down here the humidity is so high you can see the water in the air.
 
I've always followed the 70/40 rule for storage. 70ish degrees and no more than 40% humidity. I had read about this recommendation years ago and have been following it for years without any problems
 
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