S&W Model 29 Mountain Gun. The loads were factory CorBon 200gr .44 Special. The operator was an experienced shooter with military training.
The shooter started with .44 Magnums, then switched to Specials. It's likely that he expected the milder report and recoil of the .44 Special loads and therefore didn't notice the discrepancy at first.
Surprisingly, the ejector rod is fine, as are the topstrap and cylinder. Looks like a new barrel assembly should have her back up and running.
Lesson learned: be careful when switching between Magnum and Special loads, as you might not pick up on the discrepancy in time.