Yep, thats exactly what my grandfather says he did. I live in Finland, which was Germanys co-belligerent against the Soviet Union. My grandfather lived in the city of Pori and still does today. He had managed to find some Mauser cartridges and badly wanted to fire them. He knew that there was a german camp nearby so he decided that he is going to steal a rifle from there. So he went there and slowly crawled towards the camp and at the camp he found a rifle rack, quickly took one when no one was looking and crawled away. He was never caught. Unfortunately when he finally tried inserting the cartridges, he found out that the rifle was actually an italian Carcano rifle, which the germans had for unknown reasons. So naturally, the cartridges wouldn't fit. Since it was already risky enough to crawl there once, he didn't try another time.