Hi Frank. I have read several times that the 25 gr is common east of the Mississippi, and 20 gr is common in the west.......
The one box of 20 gr bullets I have, came from Gun Broker, for more $ than I care to discuss! ha ha

I had a thought (oh no) the other day. I wonder if Winchester would ever offer the .17 WSM primered brass and let us add our own powder and bullets?
I load .17 HH and these are not much smaller. Using the Hornady dies with that cool 'drop down' seating sleeve, it would be easy.

Naw, never mind..... ha ha

ron