Is there a concrete rule on which barrel dimension can be used for a given barrel channel opening? For example: could you use a #6 contour in a stock opened for a #7 or even a #8? If possible would it be adviseable to do so? I ask this, as I have picked up a few stocks over the years planning to do heavier barrel builds. My needs/opinions have changed and light to medium builds are more in order. Can/should I use smaller barrel contours or should I buy the appropriate stock for a chosen barrel contour? Thank you for your comments.