If I am reading and understanding correctly, the hold didn't go through into the chamber. It's just into the barrel threads over the chamber and left a wall thickness of .138".
Correct?
If that's so I think the work was not done as carefully as it should have been, but it's not unsafe. The cylinder walls on a 454 Casull are thinner than that, and the 454 runs a higher chamber pressure then a 308 rifle. So .138" may seem thin, and it's far thinner than the standard wall thickness, but not too thin to be safe.
