Thousands of rounds and no ringed chambers. These little styrofoam trays are soft and the single little plug disentigrates on firing. I won't use dacron or kapok. They don't disentigrate on firing. I have seen them increase pressures dramatically when used in bottleneck cases. Worse than cornmeal or cream-of-wheat. I have also seen loads that have been carried and had the powder granules disperse into dacron fibers and have irratic ignition.
If you offered me a vegetable fibre wad or similar hard wad, or a wad larger than my bullet diameter, I would not put it in my gun at all. I cut these styrofoam wad's with a sized case so they are actually not a tight fit at all.
If you have documentation regarding wads and airspace in reloads, please share it. I am willing to read any new information. If it is just someone's hypothetical dribble based on professional opinion, I probably have already gone thru it and dismissed it as such.
Steve