Winchester have always been made of unplanted brass.
Unplated primers are brass; same as the cases. Those look like copper, not brass.You've never seen un-plated primers before?
Me too, 8 1/2-120's. Still have some older reloads here with those primers still in them and they still work just fine.I shot thousands of nickel plated Winchester large rifle primers for decades, only recently have I started using the gold colour ones with my new box of 1000. WK



























