Hello to everyone!
About a year ago I had acquired a similar cartridge to this one (not this exact cartridge shown below), and have been trying to do research on it ever since.
The only information I can really find is on gunauction.com at the following link:
I must add, the head of this cartridge has no headstamp.
I know there are very knowledgable collectors in the IAA, and before emailing Winchester to ask for their opinion on it, I figured I would ask the IAA community first.
Any thoughts are welcome and appreciated!