I am almost to embarrassed to admit this, but since it is somewhat anonymous I will. I once was shooting my muzzloader. It has a peculiar habit of needing to strike the cap twice before it goes off. I lived alone in the country at the time so I was trying to determine why it was doing this by firing just the cap inside my house. So i put a cap on, and pulled the trigger. It did not fire. Then I looked down and noticed a 1 pound container of Cleanshot powder sitting there with the lid off. I shudder to think of even the best case scenario if a spark had found its way in there. I realize that shooting a cap inside the house is probably a bad idea as well.