Anybody shooting it in 257 WBY?
X-VERMINATOR
No data in the 2017 manual I downloaded a while back.
It looks to me like it's very close to IMR 7828 SSC, which is the only powder I have ever used in my 257, it worked so well I saw no need to ever try anything else.
Very close to 7828, VV560 and R22 & R25 which all work in the .257 WB so worth a try. I would see if you can calculate the approximate loads based on 7RM data from Alliant. Should be 95% of the 7RM or thereabouts.