I don't shoot that bullet in my .257R., can't give you a fav.
I'd try H-4350. It does very well with the 115 NBT. H-100V worked well with the 100 TTSX.
StaBALL may be one to try. I got mine from Powder Valley, not sure if they still have it. Haven't shot it in the Roberts.
Some like H-4831 and RL-19. I tried RL-26. It left unburned granules in the chamber; I couldn't chamber the next round.
Maybe others will chime in.
DF
