[Lycanthrope]

I think it was some bad Glock brass.

I've seen both ,and double charge usually shreds the offending round pretty hard....not just blowing out the rim on one side. They also tend to mess up ejectors, extractors and other internal parts. This is pretty mild in comparison. A half blown out rim is usually a relatively warm load ran through brass that has had the rim stretched too far..too many times.

Lycanjustmyexperiencethrope