I've been loading R-17 for almost a year now in several cartridges, 243, 6mm, 260 and have played with it in a 22-250 with good results.
As for load data, there's not much to be had, but it's a very good powder and well worth developing some loads for it to see how it works for you. I've been loading long a long time and know how to develope loads. I haven't bought a manual since 1971. I luv the results I've gotten with R-17, It's the best powder by far I've found for a 260 with 1:8 twist.