shot my .22 Mossberg 702 Plinkster , got more than i bargained for . boring till 2 min mark

Guessing i had a double fire, the initial shell in the chamber and then in cycling to the next shell , im guessing the slide overran the shell however just caught enough of the rim (In rimfire shell) to trigger the one in the clip to explode, way louder than the regular shells before that, Dammm. Chamber, slide and clip are all unharmed. Fired Tens of thousands of 22 rounds before and never anything like this....