Re: Is H335 too fast for 300 WIN MAG?
To my mind (I prefer loads with slow-burning powders with as near to 100% density), RL-17 is a bit fast for the large-case magnums. I prefer the RL-19 & H4831 range too.
RL-17 is in the "4350" range on the burn chart. Alliant has never had a powder similar to IMR or Hodgdon 4350, RL-17 finally fills that gap. I haven't tried it yet, but it is on my options list for a few smaller cartridges.
If you prefer a faster burn rate, then RL-17 or any of the 4350s will work for the .300WinMag.