I had one of those when I was a kid in the 70's (1970's, that is). I used to load them with the paper caps from the roll and drop the bomb from my stoop to the concrete patio below. If it didn't fall straight on it's nose, it wouldn't detonate. In these cases, I would yell, "DUD"!! When I got bored with that, it was always fun to just get down on the ground and strike the individual caps with a rock till they exploded..if you were really lucky, you could set the whole roll on fire..ah, those were the days!! Today's kids don't know what they're missing!