I am working up some loads in 375 imp. I am starting with new rem cases fire formed, speer 285 gr grand slams, federal magnum primers and imr 4064 powder. Also useing hornady bullets in 270 and 300 gr. Does anyone have any ideas for different powders to try, r-15 seems to be a favorite for 375 H+H? Thanks in advance

My internal program shows higher velocities with IMR 4831, IMR 4350 and RL 19. I am using 4350 in mine.

suntiet; I'am presently using RL19 (96.5 grns.- very compressed) behind a 270 Barnes X in a .375 AI (24" tube) and am getting 2915 fps avg.
I'am planning on trying WW760 and see how it performs.
Good Luck - memtb

375 Wby, Rem cases, IMR 4350, 91 gr, 26" barrel, 300 gr Sierra, Rem Mag primer, 3.65" COL, 2900 fps, same components with RL22 , 94 gr, 2800 fps. This rifle has the early Wby freebore, which in this case works out to 0.60". It allows some pretty hot loads with no pressure signs whatsoever. I would reduce these loads by 10% and start working up for a 375 AI. - Dan