To explain:
When speaking of barrel vibration a node is a crossover point where the amplituide of the wave form the particular order of harmonics that is being considered is zero. (I think) When one taps (sometimes referred to as ringing a barrel) on the barrel (free floated or hanging) the nodes sound "dead" when compared with taps on other locations on the barrel.
When node is used in reference to velocity or volume or weight of powder (Some have observed that seating depth behaves this way as well.), it generally refers to points on a continuum that yield superior accuracy, as contrasted with the loads and/or velocities between them that tend to be less productive.
As to a bullet,s knowledge of how it achieved a particular velocity, different propellants, primers, and seating depths, that yield similar velocities may not have the bullets exiting the barrel in the same part of the barrel's vibration, I think that this is due to the differences in the pressure curves that different combinations produce, and that barrel vibration is probably somewhat independent of these factors.
It is also true that a beginning handloader that is hammering together loads for his sporter barreled .308 With a Lee loader, and a plastic headed hammer(where I started) need not concern himself with some of the finer points of benchrest tuning, having bigger fish to fry,as it were.
One more thing, top shooters greatly benefit from engineering, BUT they don't engineer themselves into winning position. A lot of what has been found to work the best, has been discovered by good old cut and try, and the skills, from practice, and careful observation. Those who decry the anecdotal nature of most information that is passed around in Benchrest will grow old and gray waiting for this to change...unless they are prepared to commit the resources to do their own studies, and demonstrate that their conclusions produce superior results at matches.
- nhk