I THINK auto ignition temperature of black powder is in the 450 deg. F range, but I'm not sure about that anymore.
OK, found links to a thread with MSDS information.
It's higher than I thought.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.