Goodness, I have tried RL22, RL25, H1000, Retumbo, and IMR4350 with this 300. Yes, I had good luck with Retumbo, but not as good groups. I think with 200gr I was using 94gr of Retumbo. Didn't Chrono. I got 2.1" groups at 200 yards with this. I like H1000, and besides I got 8lb container of it.