Revolvers don't jam. The hammer can fall on an empty chamber or the bullet can be a bad load. Either way, Casey would've known. Matthew Casey states he's only alive because he "was staring down the barrel and the gun jammed". He was close enough to see whether there was an empty chamber or not. What he should've said was "there was an empty or a misfire". Besides, when a spring fed gun jams, the round has to be cleared before it can fire again.