H335 is a little fast for the 6 mm Rem, and I don't see any loads at that bullet weight for it in Hodgdon's data. QuickLOAD estimates moderate pressure (about 46,000 psi), less than great case fill (about 78%) and about 3500 fps from a 24" barrel (I don't know your barrel length off the top of my head).
Hodgdon's data site would be a good place for you to look at other powders.