Did you carry out some version of a ladder test to id a node before bedding, or just have a load that shot well? It would be interesting to compare node points pre vs post bedded regarding a change in harmonics. If the nodes are the same then there could be something different involved. I can understand the harmonics could change depending upon how well the action is being held in the rifle; think about clamping a 36" steel rod in a vice with steel vs rubber vs wood jaw face and the impact on vibration (such as a tuning fork sound if you were to strike it in this example).