There have been a couple of threads discussing Reference and Calibration components and cartridges. I’m not sure they were fully explained, at least not to my satisfaction.
The “Y” in the lot number is supposed to indicate a Calibration lot but Reference lots also contain the Y. I have several boxes of Reference Primed Cases with the lot number FA Y-7.62-468.
In todays system the Y has been replaced with “C” and “R”. R indicates the Reference Standard.
I would guess that yours are specific to the powder, WC 846.
Thanks Ray, my guess was what you stated.
I bought the box at a swap meet 6 months ago for $10.00
I was typing as you were posting. See my edit.