If you place the action into the stock without screws, does it wiggle at all?
Or is it like they were mated?
Different stock form factors also give different results.
For example, actions with an even bottom will match better than if there is any radius to the action, since even a small difference in the radius will cause pressure points.
This might not turn out to cause worsened precision, but a good stock and action mating has lots of shared surface.