hard or soft copper line for a valley oil gallery bypass line?

Newbomb Turk said
Then it doesn’t happen, even though it does. I don’t know how else to explain it.

What are you seeing the evidence that leads you to believe that pressure feeding from opposing ends of a gallery stops flow at some point along the gallery. Is there a hydraulic principle in a book or some where on the Google machine that that explains how this could happen? I might be persuaded if there was an explanation for the physics behind this. Maybe Pascal's law can explain it.

Newbomb Turk said
The same thing happens to the fuel system except we are dealing G forces. You can have full pressure on the gauge and ZERO flow.

I can see how G forces could affect flow in a fuel system during a hard launch. But I don't think we are talking about the loss of oil flow from a hard launch. So I don't see how that relates to pressure feeding from opposing ends of a gallery.