Question on fiber wads

[Woodcock survey]

I started re-loading in 1963 with a Lee loader in 16 ga. and i still have complete with instructions. Went and dug it out and read the booklet which says to decrease powder charge by 10% when using the new plastic over powder wads. I can remember doing that when i bought some Alcan plastic wads with no change in how they felt to shoot.
This does not answer your question but gives an indication that current data will give lower pressure when using all fiber wads.