I have both slow and fast twist barrels in this round. By nature of being custom chambered and who did it and what blank, so much also depends on how tight the chamber and throat is. Like in even factory barrel/ chambers, what works in one may not work in another. On my one with real tight tolerances, I found myself starting at standard chamber starting loads, and with the other not so tight, 2 grs. below max and working up. I did find that in the slow twist H4350 worked best with the light weight bullets, and while H4831SC is also a favorite, I ended up going with RL-25 in the long pointy heavy weight bullets. You just have to play around shooting and have some fun, to find out whart yours likes or dislikes.
Dave
