I shoot 90 gr. RL-25 for 2,810 fps, 30" barrel, Remington brass, Fed. 215. 300 gr. Lapua.
Mine don't like H-1000 or retumbo. 100 fps. slower and smokey.
My E.S. is 3 and my S.D. is 1. I shoot 15 shot strings over chrony, letting it cool for 5 minutes after 3 shots.
Tried the Fed. 215 M and E.S was all over.
US 869 is very temp sensitive! up to 200 fps. from 30* to 90*.
Have had good luck with RL-25. Not to temp. sensitive. at least not with my set up and low E.S.