I have this small tin, marked as per photo, it's only 2.5\" long, 2\" wide and .75\" deep. painted green with yellow markings. Gold anodised interior (empty !) it cost peanuts, it's in mint cond and has the metal box marking on the back MB 6. Does anyone know exactly what these caps were for ? I'm hoping they were for the Home Guard weapon the Northover Projector which used caps to fire the main charge, like an old musket. Any ideas ? Tony.