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20mm Oerlikon with I.S. HS..who made it?


Well-Known Member
I can`t find this HS on a 20 x 110RB Oerlikon.Any info appreciated.


  • I.S. 20mm.jpg
    I.S. 20mm.jpg
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Is this a Canadian case as it is Berdan primed? The headstamp does not look British.

However, the only "I.S". I could find in the listings is the Instrument Screw Company Ltd, Harrow.

Thanks TonyE, I don`t know if it is Canadian, It was given to me by an RCAF vet many years ago ( 1950? )
I found this HS identified on another forum as USA made by International Silver Co. of Meriden Conneticut. Sound right?
Just a guess,but maybe they just made the cases for someone else who did their own priming and loading?
20mm Oerliken

These Oerliken cases have been in our family since WW2 and were picked up near the Thames, they were always on the mantlepiece Mum loved polishing brass (actually she didn't, "but they needed cleaning") and they're paper thin.



A third case was 1942 RG OeZ