I'm new to sounding but really love it. I've got a beaded one like in this video although not as long but love the resistance it gives and the pop as the bread are pushed in and pulled out.
kime Dylan433 :The sounding rod has to be smooth with no rough edges. Insert the narrow end first so it can go through the tightness. Use more lubes. Use steel rods, thin ones of 6 to 10mm thickness as beginner. The hole will stretch when u do it more often n try bigger size slowly.