Boobytrapped AK Mags
Breach Bang Clear has the details, this was an interesting read.
Basically, it looks and feels like a full magazine. And indeed it does function like a normal magazine too–at least for a few rounds, until 35 grams of TNT blows up in your face.
Read the rest of the article: http://www.breachbangclear.com/boobytrapped-mag-in-bosnia/