Re: Is H335 too fast for 300 WIN MAG?
H335 is pretty fast burning for a large-case like the .300WinMag. It's pretty identical in performance to Reloder15 and IMR3031...too fast a burner to get peak velocity before you start running into high pressures.
I don't load for the .300, but occasionally for the 7mmRemMag which is reasonably close in case capacity and bore diameter.
For the .300WM, I would probably stick with H4831, RL19, RL22, or something in that range. RL22 is a good performer for me in the 7mmRemMag.