I had a handful of "setup" rounds I had made in 357 that made it into the good stuff...had four different squib incidents. The most interesting one was Maggie was firing her 686- first round went off, second round sounded funny so everything stopped...the bullet had extended into the barrel but had not left the casing completely and the cylinder wouldn't turn, nor could you open it. After a little while of investigation and careful thought the only solution seemed to be to take a dowel and knock the bullet back into the casing to free up the cylinder.
NOT my idea of a cool thing to do to a loaded revolver, but it was the only thing I could think of. I did it very carefully, it worked fine, and we were able to go on shooting. I found all the bad rounds, but that small flurry of incidents has made us very aware of the SOUND of each round fired. Anything odd, we stop immediately now.