Having a bang session with my 32/20 and I had a case head separation. Normally a tight patch would push the ruptured case out, but in this case it was stuck fast. Try as I might with oversized brushes and patches it would not move. Seems like a trip to the 'smith was the only solution.
Next I tried a 303 stuck case extractor, tightened the thread up and pushed the forward part into the chamber until it 'clicked' into place. Then using a 30cal rod down the barrel to tap the extractor and presto the offending broken case released.
Should be able to use this method on any 310 Cadet as well.