NRVO readers may find this interesting.  It was sent to me by a friend in Maryland. 

I went to the range for the first day of shooting this year and decided to shoot black powder with a friend. We were the only ones on the range.
At about the end of the day I dropped something in front of the firing line, so I asked if we were "clear," got the "OK" and went forward.

Next thing I knew, my friend shouted "FIRE!"

I told him, "Don't fire! The range is 'cold'!" But he repeated, "FIRE!"

Again I responded, "Don't Shoot!" Whereupon he pointed to the target, merrily blazing away behind me from part of our black power discharge!

This sort of thing can occasionally happen with black powder guns:  a wad may catch fire from the powder discharge, and it's not unknown for a blazing wad to ignite nearby vegetation.  In the American Civil War, at the Battle of the Wilderness, this happened. Wads from muskets started a forest fire that burned many soldiers to death!

Moral of the story: be careful out there and be aware of this danger especially in the dry season.