US WW2 20x110 Headstamp question


I have two US-Made WW2 20x110 Hispano cases, which I have been unable to identify. The headstamps are: “ASC 1942 20MM M21A1” and “G.M.S. 1943 20MM M21A1” What factories used these headstamps?



“ASC” = A.S. Cambell Co Inc., Boston, MA.
“G.M.S.” = Globe Machine & Stamping Co., Cleveland, OH.

Best regards, Rob


Thanks Rob, I’ve had those 2 cases for ages and couldn’t find anything on them. You wouldn’t happen to know this one would you? It is Steel-cased 20x139 stamped “D 00 VM 20mm”