First thought, go on accurate shooter and ask the members what has been working for them.... http://forum.accurateshooter.com/index.php?board=7.0

Make sure you provide all info on your rifle.

Have you done a Ladder Test on the loads you think are most promising?

Do you know the precise chamber length, and chamber neck size?

Are you checking concentricity of the rounds?

Seating depth may have a positive outcome, but you need precision measurements.