Ok well then (to carry on my conversation with myself here), I found
THIS:
“According to Rick Patterson, Managing Director of
SAAMI, "In fact as long as your ammunition is stored at normal room temperatures with low humidity, it can function reliably for decades."
It takes more than just a warm day to detrimentally impact ammunition -- SAAMI believes the breakdown begins around 150 degrees Fahrenheit. There are very few environments where stored ammo can reach those extremes, but the trunk of a vehicle is one of them.
"Definitely avoid storing ammunition in a car on a hot sunny day- that's probably the single most likely scenario that could cause problems for the average shooter," Patterson explained. "With extremely high temperatures, you get rapid degradation of the ammunition components. The case and bullets are relatively inert in terms of temperature, but the chemical properties of the gunpowder and priming mixture can be affected ... Over time, you'll see a drop in performance, perhaps to the point of going
click rather than
bang."
So ...
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