The 3 holes are found on non military helmets for ARP, Police, Fire Services etc-it indicates lower quality steel used to make them-military helmets...
From the condition and calibre (the Germans couldn't make them in 9mm Parabellum due to the conditions of the Versailles treaty post 1919), it might...
I have a silver plated teaspoon with the GS badge engraved on it-not sure how old it is though-'liberated' it from the kitchen at my old Res signals...