What are the possible causes of a bulged case?
Was at the range a few weeks ago. A friend was firing commercially reloaded .45 ACP 200gr SWC in a full size Baer. Don't know what powder. Heard an extra loud shot and stopped - didn't sound right. No barrel obstruction and the gun looked fine. We searched around and found the case. It was bulged at the rear where it sat over the feed ramp, and the primer was blown out. No cracks in the case. What are possible causes of this?
Seems likely it was simply a double charge, but what other possibilities are there? Bullet setback causing extra pressure? Anything else?