I grew up in a country with very strict gun control (Germany) and did almost the same thing that timonovici did. We used to collect blanks in the woods, thrown away by NATO troops during maneuvers. I don't remember what I was expecting, but I too remember the bang being so loud to make me dizzy - I think I wasn't sure for a few moments if I was dead or alive.
Just a few days ago I wrote a comment [1] about a boy who used to live a few kilometers from my house when we were children and lost half of his hand doing experiments in his parents basement.
I think fire and exothermic reactions in general are much too interesting for children to not find a way to experiment with them at one time or another, but parents should take care that children don't do it alone and that they do it in a safe way.
I also (partly) grew up in (what was West) Germany but I am British. My dad was an ATO but by that time he generally ran ammunition depots. From a very early age (5+), me and my brother were taught how to look for "devices" under cars and other skills that kids should not need.
Dad was called out to mop up after a young lad found an unexploded mortar shell and put it in a bench vice and whacked a nail into the firing pin. He has several more harrowing tales along those lines.
Gosh what fun old days those were. This was the era of the Cold War, at school we would have a bomb scare nearly weekly, Rheindahlen E mess was bombed, troops were shot at by quite a variety of nasty people and other fun and games. Mind you, a CSM pinched a Saracen or Saladin and tried to run down a bloke who was playing away with his wife. He drove it over the other bloke's car first. Shandy was involved.
On the bright side, I have friends from afar that I'm in touch with today - 40 odd years later.
This was not talked about much because it was a criminal offence, but growing up at that time in that area we were all the same and I could tell you a bunch of other stories like that.
Collecting the rounds was like a sport. The one with the biggest collection was the winner. Sometimes we found elements from ammunition belts too. They were rare and because of their small size and dark color much more difficult to find than the larger untarnished brass colored cartridges. One of the boys from my town had the perseverance to collect enough elements to assemble a belt that he could wear over his shoulder. He looked like John Rambo.
All of this wasn‘t a local phenomenon either. Much later I learned the story of a boy from a different area whose house was searched for pirated home computer games. Police didn‘t find any pirate copies but they found the blanks he had collected. Strict as the gun laws are he got a young offender sentence for unauthorized possession of a firearm (unerlaubter Waffenbesitz).
And this was all only about thrown away blanks from NATO maneuvers. When it comes to all the weapons that “disappeared” basically over night at the end of World War II, I know there is another trove of stories, but these are for someone from another generation to tell.
You might have heard about the BBC serial The Machine-Gunners, which tells a related story from the British perspective. It was very popular with us kids in Germany at that end of the Eighties. The opening theme Colonel Bogey March is now stuck in my head..
Just a few days ago I wrote a comment [1] about a boy who used to live a few kilometers from my house when we were children and lost half of his hand doing experiments in his parents basement.
I think fire and exothermic reactions in general are much too interesting for children to not find a way to experiment with them at one time or another, but parents should take care that children don't do it alone and that they do it in a safe way.
[1] https://news.ycombinator.com/item?id=16698251