An accident waiting to happen that I recall the most was on a small exercise on an open field firing area and getting into an old trench and dropping a load of blank while reloading some of the magazines. Picked them up and realised that there were live rounds in my hands and I'd picked up a load of live from the floor of the trench. As I was one of the DS, I had to pick them up and keep them safe AND away from the blank that I also had. Blank and BFA's = trouble!