I would really love to hear from some of the older guys. I am a relative newbie, and these stories can (hopefully) help guys like myself learn from others mistakes.
I personally don't have any overly dramatic stories to tell. Within my first week of casting, I was smelting down range scrap. I had hosed it down and left the bucket to dry in the sun for several days. I skimmed off the first run of dross and junk, and piled a new load on top of the molten lead. I stepped inside to give it a few minutes to melt down. About 30 seconds later I heard what sounded like a small caliber handgun shot from the porch. I opened the door to about 5 of the 20 lbs of molten lead spattered in all direction. Obvious to me know, a bit of moisture was trapped inside one of the deformed slugs. First lesson learned. NEVER add range scrap to a loaded hot pot! Had I been outside, I would have been severely burned.
Another less intense, but nearly as scary, incident occurred whilst casting. I was in water dropping .45 acp boolits when a droplet splashed up and into my mold. This happens occasionally, but is usually vaporized almost instantly. For whatever reason, this one did not. As I poured the next cast, the effected cavity regurgitated 200-250 gr.'s of hot lead straight up and out. Most hit bottom of the pot, and I got several small gobs to the face. After cleaning myself off (and changing my shorts) I put my glasses back on, to find a nice round splat of lead over my left eye. Glasses saved my eye.