Additional thought, as My Hughes says above, check that you don't have little breech vent screws locking the DSSD in place. From what I remember of the gun (plus the fact that you have got one out already), you don't but do check anyway. Like most gunsmiths I once fought with 'stuck' DSSD in my early years only to find that they were locked in place all the time by something else. 10 seconds later they were lying in my hand. Extremely embarrassing!