DD
Thanks for the photos. They are what I had imagined, but never seen before.

FWIW, I have a set of bore pigs from Skip Epp, who supplies them with a plastic tubing push-rod. It isn't delrin, but it feels pretty close to that. They can be coiled and they are easily stiff enough to push anything reasonable through and out the bore. Similar idea to what you have.

I have seen similar tubing in a hardware store somewhere, but I can't seem to find it again. The cable maybe a good alternative.

Brent