If the other empty cases look alright, especially fired after that one, you can likely rest assured that it was a faulty case that ruptured. Inspect the chamber rim and the empties and if there is no apparent cause, you can just forget about it. An anomaly.
Sometimes you get what you pay for, sometimes you only pay more for what you get.
Three shots are not a "group"...they are a "few".
If the Bible is the literal, infallible, unerring word of God...where are all those witches I am supposed to kill? (Exodus 22:18)