RL-25 has by far been the best performing powder for my 300 RUM both in accuracy and velocity. I run top loads with awesome accuracy.
I have noticed a bit of differance in loading from lot to lot. I just moniter my velocity and if its lower, I add, if its higher I drop it some. As soon as I make a small adjustment, presto, groups are pefect again.
I have used four lots of powder and each time I get perfect accuracy even though I have to adjust slightly. I have used other powders that no matter what I did, the new lot just would not group despite the old one being excellent.
It took quite a while to find my 300 RUM load. Using a Lilja 27" barrel on a REM 700 action, I found that 98.8 grains of H1000 did the trick for me. My 180 grain Barnes TSX moves out at 3450 fps and groups just under half MOA. I found RL-25 and RL-22 produced higher velocities, but the fps had a greater variance between shots.
Hey all new guy here. I have been running 180 gr Accubonds in front of a max load(102.5 gr) of Retumbo. They have been grouping @ around an inch consistantly. This load is on the warm side in my gun. Any RE 22 or 25 recipes folks want to share would be appreciated. Thanks