I'm sorry... But perhaps I'm too dense to figure it all out, but my issue with the whole, nodes are predicable issue is, perhaps if you have an engineering degree, and the proper lab to test various metals, how they were forged, points of contact with different stock materials, thickness and taper of the barrel, change in rifling, powder variables, etc etc etc.... Perhaps you could lay out a predictable pattern for nodes.
Since most people don't have the luxury of time or money for such experimentation and data collection, the most reliable and easiest method to determine the nodes for "your" rifle are to work up some loads... Go to the range.... And test it there, taking notes on the results you find. Even changing brass and or primers and or powder and or seating depths and or .... (I could go on and on)... Affect the vibrations in the barrel to a point that one given change can throw accuracy and consistency of a given workup, out the window.
Take (2) guns from the same manufacture, same make, caliber, stock, and twist rate, and I'll bet you'll find that they don't like the same bullet powder combination. They might have a similar pattern with respect to distance between nodes,but they might not. Been doing this long enough to know a "mirage" when I see one.... And in my humble estimation, node prediction is exactly that.
If node prediction was easy, reduced time, and cheap... Trust me when I say that everyone here would do it, because as humans, we tend to prefer the easiest, fastest, and least expensive method to get a desired result.
Best wishes to you in your endeavor and good luck. If you figure out a golden rule for node distance, you can probably develop an app for it and retire. Here's to hoping you do.
