If it doesn't eject when you retract the barrel – because there is no tang on the taper, or it is too short – try using wedges between the back of the chuck and the end of the tailstock barrel.
Brutal method – hold one end of a piece of round bar in the lathe chuck, and 'tother end in the tailstock chuck. Lock the barrel but make sure the bed clamp is slack, then give the front of the tailstock a whack using a piece of wood as a drift.
Phil