Yea, there is a window of operation. But for a 30-06, it shouldn't be too hard. For my 270, it was difficult. 4350 or faster will give you what you need. I would stay away from H1000 loads.

I had trouble loading 4064 and varget loads in my 270. 4350 was the only powder that gave me good accuacy and cycleing. I am sure many more are out there, but its what I had good luck with.