This is a W&S action , This should be the breech pin . There is an unexplained screw on the trigger plate behind the triggers , to far forward for the hand pin .It looks as if the stock has been cracked , repaired and the trigger plate extended .
A suggestion is that you fire the gun , remove the sear springs and sears . I know this sounds odd but I have come cross some boxlocks that this is needed to to take the stock off .I have a feeling this may be one of them .