I don't know if this qualifies as a "reloading" goof...but here goes. Back when I was about 12 or 13, I was always trying to make black powder. Could never get it to go like real stuff..only a semi-fast burn. Found a half-used road flare & mixed some of that in..not much better. Took one of my dads paper 12ga. shells & opened up. Mixed this with my own & got a little better burn. Using opened shell, I stuffed as much powder in as I could compress & still get all felt wads back, folded & glued crimp. Next afternoon as it was getting dark, I took shell into woods back of house & pondered how I might set it off. wedged it in woodpile & thought about shooting primer with BBgun, but didn't think I could hit so small a target without getting real close...(good thing for me I didn't try this). Finally I hit upon the brilliant idea of centering shell on muzzle of said gun, held this over top of head as far as outstretched arms could reach, kind of scrunched head down and almost closed eyes..I still wanted to see what would happen...& pulled trigger. With a thundering roar, the woods around me lit up as if it were noon! Found shell on ground..only brass head left..then I noticed the battery cup primer was missing..like a fool I looked for it on ground..then I happened to look at BB gun muzzle... that primer of about 1/4" dia. had been forced over 2 inches down that .177 bore!
Then it finally sunk into my thick skull, and I started to shake...what if for some reason, that primer had skidded off that muzzle..and my head right under it! My guardian angle must have earned his overtime that day!