Jope,
Your post is a bit confusing. What powder are you using. Hodgdon H110 or Vihtavuori N110. These two powders have different burning rates. N110 is slightly faster then H110.
You might also want to give Hodgdon Lil'Gun a try. I have found this powder to preform well in the 300 Whisper.
As far as suggested loads. Both Sierra and Hornaday manuals have reloading data for the 300 Whisper. If you give Sierra and Hornaday a call the will either fax or e-mail you the load data.
There are also some links here on quarterbore:
http://www.quarterbore.net/forums/showthread.php?t=189
I have also posted a few loads here:
http://reloadersnest.com/frontpage.asp?CaliberID=135
Most of the loads posted under "not yet verified user loads are mine with the exception of load #'s:
2973, 2974
3299, 3577
I hope this helps
320pf