Thread: Old powder wrecked reloading gear.

Greetings,
I also would not rule out moisture as at least part of the problem. In spite of the sunny day there would have been moisture in the air. As air cools the humidity goes up even with the same amount of moisture. Humidity is a percentage of the moisture that can carry at that temperature. At some point as it cools the moisture starts condensing on cool things like metals and voila rust. The towels may have aggravated things as well. It is likely that you sealed the moisture in when you closed the container.
Regards Grandpamac.