British Vickers MMG Receiver Shutter (Ejection Port Cover) Assembly Complete

Original Item:  "Shutter" is the term used by the British military to describe ejection port cover of the Vickers gun.  The shutter consists of a sliding metal plate with a dual-purpose spring-loaded catch.  The catch assembly holds the shutter in either the open or closed position while an additional spring stud retains the shutter in the receiver unless it must be removed for cleaning or maintenance.