Getting the casing out of the shellholder should be no issue at all, since the jaws automatically open to allow that removal.
You need to adjust the pointed stem on the frame [below the cradle] upwards until it wedges between the two plates as you lower the cradle fully after sizing.
This wedging action will separate the plates, and if adjusted correctly, allows you to remove the case without any obstruction.
All cases of .420 to .512" diameter use the same plates. For the small cases, you need to turn the plates. [watch those little springs!!]
Regards, Dave.