John, great update! Those "bulletshaped" thingies are most often found when the "wires" are actually "flat oval" lengths of metal. Sometimes they are also seen as "sticks" going all the way between the crosses front and back on a rigging. They are there to keep the movement at bay, as the "wires" are semi-airfoilshaped, not really to keep the wires from rubbing (they should be tensioned sufficiently to avoid that). One instance where you can see the full-length stick used is in the Stearman.
I had the pleasure of being around one of these for a lot of years - here we are pulling it out for run-up after the winter.
As the wires on the stearman are not really close due to the stagger and the anchorpoints, it makes perfect sense here to make good use of the full-length stick-type
I hope this explanation and the pictures makes sense
@johnb, if further is needed just send me a PM and I shall try to deepen.
Your build makes a lot of progress, and I shall be looking forward to this very nice "hydrobipe" in the headlines soon! 🙂