It sounds like the rifle had excess headspace before, and that was the cause of the blowup, not the result of it. Since diagnosis long distance is not really feasible, I recommend you take it to a gunsmith and see if there is something seriously wrong and if so whether it can be fixed, or call Mossberg and ask about returning it to the factory for a checkup.
I can only say that AFAIK, those rifles are pretty good and not prone to giving trouble.
Jim
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