"... had loaded with a double charge and the report was loud and recoil was extreme."
Over confidence leads to carelessness, carelessness leads to damage. That buddy was overconfident.
Instead of assuming I have done everything correct I always assume I make a mistake and check everything before moving to the next step, especially when charging pistol cases. In some 45+ plus years I've never harmed me or a weapon or anyone else. But I still recheck.