RE: Ideal Humidity for storing guns and powder
Bigcountry,
For human comfort about 50-55% is good. So I'm guessing the same for firearms. As far as a good tool for testing humidity a sling psychrometer is very accurate. The higher humidity in the summer would be more detrimental to the primers and powder than the lower humidity. If you use A/C in the summer this should keep your house at an acceptable humidity level.
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